Volume 38 / No. 7 / 2023
Moldavite from
Chlum, Czech
Republic
History and Properties
of the Banjarmasin
Diamond from Borneo
Asterism in
‘Mercedes-Star’
Quartz
Cause of Colour
and Dichroism in
Laurentthomasite
b THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 i
GEM NOTES
The Journal is published by Gem-A in collaboration with SSEF.
ARTICLES
Banjarmasin Diamond: War Booty from Borneo
in Amsterdam
By Suzanne van Leeuwen and J. C. (Hanco) Zwaan
Clues to Understanding the Enigma of the Unusual
Asterism in ‘Mercedes-Star’ Quartz
By Jean-Pierre Gauthier, Emmanuel Fritsch,
Thanh Nhan Bui and Jacques Fereire
Moldavite from Chlum, Czech Republic:
Mining and Gem Properties
By Tom Stephan, Štěpán Jaroměřský,
Lukáš Zahradníček and Stefan Müller
Origin of the Colour and Dichroism in Laurentthomasite
By Isabella Pignatelli, Cristiano Ferraris and Dominik Schaniel
662
678
696
708
641
Volume 38 / No. 7 / 2023
ISSN 1355-4565 (Print), ISSN 2632-1718 (Online), https://doi.org/10.15506/JoG.2023.38.7
Cover photo: The 38.23 ct Banjarmasin diamond, in the
collection of the Rijksmuseum in Amsterdam, the Netherlands,
was cut from a 70+ ct octahedral crystal that was reportedly
mined in southern Borneo. The rough stone was confiscated
by the Dutch from the Sultanate of Banjarmasin in 1860, and
it was faceted in Amsterdam in 1870. An article on pp.
662–677 of this issue describes the diamond’s history and
gemmological properties. The diamond is shown over a
colour-inverted image of the old map in Figure 4 of the
article. Photo by Frans Pegt; courtesy of Rijksmuseum
(inv. no. NG-C-2000-3).
Volume 38 / No. 7 / 2023
Moldavite from
Chlum, Czech
Republic
History and Properties
of the Banjarmasin
Diamond
Asterism in
‘Mercedes-Star’
Quartz
Cause of
Colour in
Laurentthomasite
708
Photo by Jeff Scovil
696
Photo by Jan Loun
646
New Media
Learning Opportunities
Gem-A Notices
Conferences
5th Italian National Conference of Gemmology
Literature of Interest
726
724
722
733
718
658
Photo by Ozzie Campos & Rosiane Pereira
COLUMNS
What’s New
DiaSynth Diamond-detection
Device | CIBJO Congress 2023
Special Reports |
Gemmological Society of
Japan 2023 Annual Meeting
Abstracts | LMHC Gemstone
Information Sheet Updates |
Natural Diamond Council’s
Diamond Facts Report |
Sarine’s CarbonVERO
Diamond Traceability
Solution | SSEF Update on
Irradiation Treatment of Gem
Corundum | Trade Alert on
Cr-diffused ‘Ruby’ | Rapaport
Podcasts | Tea & Gemstones
Podcasts | Collectible
Minerals Exhibit in Paris,
France | Gübelin Gem
Museum Opens
Gem Notes
‘Aquafire’ Beryl from Brazil |
Emerald and Green Beryl
from Shaanxi Province, China |
Unusual Colour-zoned
Emerald | ‘Star of David’
Pattern Produced by Trapiche
Emerald | Update on
Rhodizite-Londonite from
Manjaka, Madagascar |
Sphalerite from Balmat, New
York, USA | Tourmaline from
Calabar, Nigeria | Sapphire
Coloured Blue by a Polymer
Coating | Mystery Pendant
Watch Made by Fabergé?
ii THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
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PRESIDENT
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VICE PRESIDENTS
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HONORARY FELLOWS
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Terrence S. Coldham
Richard Drucker
Emmanuel Fritsch
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HONORARY
DIAMOND MEMBER
Martin Rapaport
CHIEF EXECUTIVE OFFICER
Alan D. Hart
COUNCIL
Justine L. Carmody – Chair
Nevin Bayoumi-Stefanovic
Maggie Campbell Pedersen
Kate Flitcroft
Joanna Hardy
Philip Sadler
Pia Tonna
BRANCH CHAIRS
Midlands – Craig O’Donnell
North East – Mark W. Houghton
North West – Liz Bailey
South West – Rachael Boothroyd
EDITORIAL STAFF
Editor-in-Chief
Brendan M. Laurs
brendan.laurs@
gem-a.com
Executive Editor
Alan D. Hart
Editorial Assistant
Carol M. Stockton
Editor Emeritus
Roger R. Harding
ASSOCIATE EDITORS
Ahmadjan Abduriyim
Tokyo Gem Science LLC,
Tokyo, Japan
Raquel Alonso-Perez
Harvard University,
Cambridge, Massachusetts,
USA
Edward Boehm
RareSource, Chattanooga,
Tennessee, USA
Maggie Campbell
Pedersen
London
Alan T. Collins
King’s College London
Alessandra Costanzo
National University of
Ireland Galway
John L. Emmett
Crystal Chemistry, Brush
Prairie, Washington, USA
Emmanuel Fritsch
University of Nantes,
France
Rui Galopim de Carvalho
Gem Education Consultant,
Lisbon, Portugal
Al Gilbertson
Gemological Institute
of America, Carlsbad,
California
Lee A. Groat
University of British
Columbia, Vancouver,
Canada
Thomas Hainschwang
GGTL Laboratories,
Balzers, Liechtenstein
Henry A. Hänni
GemExpert, Basel,
Switzerland
Jeff W. Harris
University of Glasgow
Alan D. Hart
Gem-A, London
Ulrich Henn
German Gemmological
Association, Idar-Oberstein
Jaroslav Hyršl
Prague, Czech Republic
Brian Jackson
National Museums
Scotland, Edinburgh
Mary L. Johnson
Mary Johnson Consulting,
San Diego, California, USA
Stefanos Karampelas
Laboratoire Français de
Gemmologie, Paris, France
Lore Kiefert
Dr. Lore Kiefert Gemmology
Consulting, Heidelberg,
Germany
Hiroshi Kitawaki
Central Gem Laboratory,
Tokyo, Japan
Michael S. Krzemnicki
Swiss Gemmological
Institute SSEF, Basel
Shane F. McClure
Gemological Institute
of America, Carlsbad,
California
Jack M. Ogden
London
Federico Pezzotta
Mineralogical Collection
Professionals, Milan, Italy
Gérard Panczer
Claude Bernard University
Lyon 1, France
Jeffrey E. Post
Smithsonian Institution,
Washington DC, USA
George R. Rossman
California Institute of
Technology, Pasadena, USA
Karl Schmetzer
Petershausen, Germany
Dietmar Schwarz
Zmpery Gemology Lab,
Shanghai, China
Menahem Sevdermish
Gemewizard Ltd, Ramat
Gan, Israel
Andy H. Shen
China University of
Geosciences, Wuhan
Guanghai Shi
China University of
Geosciences, Beijing
James E. Shigley
Gemological Institute
of America, Carlsbad,
California
Christopher P. Smith
American Gemological
Laboratories Inc.,
New York, New York
Elisabeth Strack
Gemmologisches Institut
Hamburg, Germany
Tay Thye Sun
Far East Gemological
Laboratory, Singapore
Frederick ‘Lin’ Sutherland
Port Macquarie, New
South Wales, Australia
Pornsawat Wathanakul
Kasetsart University,
Bangkok, Thailand
Chris M. Welbourn
Reading, Berkshire
Bear Williams
Stone Group Laboratories
LLC, Jefferson City,
Missouri, USA
J. C. (Hanco) Zwaan
Naturalis Biodiversity
Center, Leiden,
The Netherlands
CONTENT SUBMISSION
The Editor-in-Chief is glad to consider original articles,
news items, conference reports, announcements and
calendar entries on subjects of gemmological interest
for publication in The Journal of Gemmology. A guide
to the various sections and the preparation of manuscripts is given at https://gem-a.com/membership/
journal-of-gemmology/submissions, or contact the
Editor-in-Chief.
SUBSCRIPTIONS
Gem-A members receive The Journal as part of their
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libraries, museums and similar institutions may become
direct subscribers to The Journal; download the form
from The Journal’s home page.
ADVERTISING
Enquiries about advertising in The Journal should
be directed to [email protected]. For more
information, see https://gem-a.com/component/
edocman/media-kit.
COPYRIGHT AND REPRINT PERMISSION
For full details of copyright and reprint permission
contact the Editor-in-Chief. The Journal of Gemmology
is published quarterly by Gem-A, The Gemmological
Association of Great Britain. Any opinions expressed
in The Journal are understood to be the views of the
contributors and not necessarily of the publisher.
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PRINTER
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© 2023 Gem-A (The Gemmological Association
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ISSN 1355-4565 (Print), ISSN 2632-1718 (Online)
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THE JOURNAL OF GEMMOLOGY, 38(7), 2023 641
WHAT’S NEW GEM NOTES
What’s New
INSTRUMENTATION
Italy-based DiaTechPro released its DiaSynth device in
mid-2023. The instrument employs a combination of
‘internal artificial intelligence’ (developed in collaboration with the University of Verona) and ‘photography
of UV induced visible fluorescence’. This methodology reportedly considers about 120 features for each
sample to distinguish natural diamond from synthetics
(both CVD and HPHT), as well as common simulants
such as cubic zirconia and synthetic moissanite. It can
accommodate loose stones as well as jewellery such as
rings and bracelets. Visit https://www.diatechpro.com.
NEWS AND PUBLICATIONS
Several special reports prepared in advance of
the October CIBJO Congress in Jaipur, India, are
available for download at https://www.cibjo.org/
congress2023-special-reports. They cover issues
planned for discussion during the conference by the
various CIBJO commissions, and as of early September
they included: Bringing Clarity to the Industry and
Consumers by Setting Criteria for Gemstone Variety
Names (Gemmological Commission); Demand for
Coloured Gemstones Is High in Post-COVID Market, but
Challenged by Undetected and Undisclosed Treatments
(Coloured Stone Commission); In Our Ever-Changing
Jewellery World, How Can One Compete Successfully?
(Marketing & Education Commission); Moving Beyond
Responsible Sourcing Towards a Shared Understanding
of Our Sustainability Impacts (Sustainable Development Commission); Protecting Intellectual Property in
the Jewellery Industry: Defending Both the Art and the
CIBJO Congress 2023 Special Reports
DiaSynth Diamond-detection Device
Creative Spirit (Ethics Commission); While Geopolitics and Consumer Sentiment are Agents of Change,
Industry Standards Remain Grounded in Scientific
Discipline (Diamond Commission); and While Precious
Metals Retain Their Safe Haven Status, Sustainability
and Responsibility [Are] More Pressing Issues (Precious
Metals Commission).
GEM NOTES
642 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
WHAT'S NEW
Israel-based Sarine Technologies Ltd introduced
its CarbonVERO system in July 2023. It provides a
method of recording ‘the energy consumption and
carbon footprint of each individual diamond’ from
its mine origin to the polished gem. The data can
Released in April 2023, Diamond Facts: Addressing Myths and Misconceptions About the Diamond Industry provides answers to questions
such as ‘Is it possible to tell a laboratory-grown diamond from a
natural diamond?’, ‘How do I know whether I’m purchasing a natural
or a laboratory-grown diamond?’, ‘Are all laboratory-grown diamonds
sustainable?’, ‘What is the natural diamond industry doing to reduce
its carbon footprint and protect biodiversity?’, ‘What have been the
price trends for laboratory-grown diamonds?’, ‘Do natural diamonds
benefit the countries where they come from?’ and others. Factual
answers to each question can be used to inform consumers and
raise confidence in the industry. View the report online at https://
www.naturaldiamonds.com/diamond-guide/diamond-facts-fullreport or download it at https://www.naturaldiamonds.com/press/
diamond-facts-report.
Gemmological Society of Japan 2023
Annual Meeting Abstracts
Abstracts of lectures presented during the June 2023
Annual Meeting of the Gemmological Society of Japan
are available at https://www.jstage.jst.go.jp/browse/
gsj/45/0/_contents/-char/en. The 23 abstracts cover a
variety of topics (in Japanese with English summaries),
including fluorescent opal, star peridot, Paraíba-type
tourmaline, irradiated and ‘hybrid’ diamonds (CVD
synthetic overgrowths on natural diamonds), lustre and
fluorescence of akoya cultured pearls, and more. Also
available are abstracts from previous GSJ conferences.
LMHC Gemstone Information Sheet
2023 Updates
The Laboratory Manual
Harmonisation Committee
(LMHC) updated seven of
its 13 Gemstone Information Sheets in January
and February 2023: No. 2:
Corundum – Lattice Diffusion of Foreign Elements Other
Than Hydrogen; No. 4: Padparadscha Sapphire; No. 5:
Emerald – Fissure Filling/Clarity Enhancement; No. 6:
Paraíba Tourmaline; No. 8: Gemstones Where Colour
Authenticity Is Undetermined; No. 9: Alexandrite and
Other Colour-Change Gemstones; and No. 12: Organic
Fillers (Oil, Resin, Wax) in Gemstones. Download the
sheets at https://www.lmhc-gemmology.org/gemstones.
Natural Diamond Council’s Diamond Facts Report
then be accessed via Sarine’s Diamond Journey
traceability solution. The system is the result of
collaboration with diamond manufacturer and
trader Andre Messika Ltd and The Carbon Trust,
a renowned authority in carbon emissions assessment. The Carbon Trust created the foundation
database, incorporating annual input of materials,
energy, transportation, processing, ancillary
and waste data, as well as the method of determining carbon footprint. Visit https://sarine.com/
carbonvero.
Sarine’s CarbonVERO Diamond Traceability Solution
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 643
WHAT’S NEW GEM NOTES
Trade Alert on Cr-diffused ‘Ruby’
In July 2023, a trade alert was posted by
Jeffery Bergman of EighthDimensionGems,
Bangkok, Thailand, about a 7 ct ‘ruby’ treated
using high-temperature heating combined
with surface diffusion of Cr. The stone had
abnormally high RIs of 1.772–1.778, and
the treatment became apparent when microscopic observation in immersion revealed
uneven colour concentrations at the surface.
Although this treatment has been known for
decades, it is not often encountered today,
and this stone was reportedly treated recently.
Included with the description of the stone
are useful photomicrographs of characteristic surface and internal features. View the
report at https://eighthdimensiongems.com/
chromium-surface-diffusion-treated-ruby.
SSEF Update on Irradiation
Treatment of Gem Corundum
In July 2023, the Swiss Gemmological Institute
SSEF posted a research update on the irradiation treatment of corundum at https://tinyurl.
com/mryhkdcs. The report provides preliminary
data from SSEF’s experiments using a linear accelerator in an attempt to replicate results of recent
reports that cancer radiotherapy equipment
has been used to enhance the colour of slightly
purplish red rubies and pink-to-purple sapphires.
SSEF found that not all samples were affected by
such irradiation, and most that did react tended to
turn an unstable orangey colour; not all of them
returned to their original colour with time. To date,
no reliable method of detection has been identified.
OTHER RESOURCES
Rapaport Podcasts
Since the beginning of 2023, Rapaport has released 17 podcasts on a broad
range of diamond-related topics. Among these is a 6 July interview with
Dr Thomas Hainschwang about the challenges of identifying natural vs
colour-treated green diamonds, and an 18 July discussion with Amish
Shah (founder of Altr Created Diamonds) about the inaugural Lab-Grown
Diamond Symposium that took place on 10 July 2023 in Dubai, United
Arab Emirates. This symposium gathered industry members to discuss the
economics and marketing of synthetic diamonds, as well as issues such as
sustainability and ethics. To hear these and other podcasts, visit https://
rapaport.com/type/podcasts.
GEM NOTES
644 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
WHAT'S NEW
Tea & Gemstones Podcasts
Jewellery historian Jennifer Sieverling offers an educational but
light-hearted look at gems and jewellery on Apple Podcasts in
her Tea & Gemstones series. As of this writing, 36 podcasts were
available, with five added in 2023: ‘The Imitators’ (diamond
simulants), ‘Labradorite’, ‘Carmen Lucia Ruby’, ‘History of Birthstones’, ‘JUSKA (Jewelry U Should Know About): Daniela Villegas’
and ‘Gemstones of the Zodiac’. Visit https://podcasts.apple.com/
us/podcast/tea-gemstones/id1583839944.
MISCELLANEOUS
The Musée de Minéralogie, Mines Paris – PSL in
Paris, France, is hosting a temporary exhibit titled
Minéraux : Objets de Collection (Collectible Minerals)
until 9 March 2024. It features hundreds of mineral
specimens—acquired over two centuries through
purchases, field collecting, revolutionary seizures,
donations, exchanges and heritage preservation—
many of which are not normally on display or
assembled in one place. The museum was created in
1794 and has more than 100,000 samples, representing
over 1,000 species. Information on the exhibition is
available at https://tinyurl.com/msca9a9y, and an
informative and well-illustrated catalogue can be
downloaded at https://tinyurl.com/yckm4s3y.
Collectible Minerals Exhibit in Paris, France
What’s New provides announcements of instruments, technology, publications, online resources and more. Inclusion in What’s New does not imply
recommendation or endorsement by Gem-A. Entries were prepared by Carol M. Stockton (CMS) or Brendan M. Laurs (BML), unless otherwise noted.
Gübelin Gem Museum Opens
In July 2023, the House of Gübelin opened the Gübelin
Gem Museum in Lucerne, Switzerland, on the occasion of
the 100th anniversary of the Gübelin Gem Lab. The museum
houses the lab’s reference collection of more than 28,000
gem specimens, many collected at their source by Dr Eduard
Gübelin during his travels. In addition to 174 samples from
his collection, the museum also includes displays of Gübelin
history, watches, jewellery and gemmological instruments,
and provides interactive educational experiences. Visit https://
www.gubelin-gemmology.com.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 645
WHAT’S NEW GEM NOTES
Every day, our in-house experts carefully select a wide range of gemstones
from around the world for every collector.
Puri cacion Aquino Garcia
Expert Gemstones
Buy and sell on catawiki.com
Bid on exceptional
gemstones, selected by
Catawiki experts
646 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
COLOURED STONES
‘Aquafire’ Beryl from Brazil
Gem Notes
In March 2019, a new find of aquamarine occurred
in Minas Gerais, Brazil, which displayed abundant
irregular and spotty orangey yellow to yellowish
green or brownish orange inclusions (e.g. Figure 1).
About 200 kg of rough material were recovered as
broken pieces, some with flat areas corresponding
to beryl’s poorly developed cleavage on {0001}. The
entire production was obtained by Gems in Gems
(Seville, Spain), and so far they have faceted about
5,000 carats in sizes up to 23×13 mm (e.g. Figure 2).
The stones are cut to show their inclusion scenery,
particularly the orangey yellow to yellowish green
areas, as well as iridescent colours displayed along
fractures or on the surfaces of the inclusions (e.g.
Figure 3). The appearance of the beryl resulting from
the combination of these characteristics inspired
Gems in Gems to call it ‘Aquafire’. In order to characterise the material and its inclusions in more detail,
Gems in Gems kindly donated three of the stones to
Gem-A: a 10.29 ct trilliant, a 5.07 ct cushion-shaped
modified cabochon and a 3.26 ct trilliant (again, see
Figure 2).
Examination of the stones by authors AC, CW and
BW confirmed that all the samples were beryl. They
were pale coloured and ranged from aquamarine
(greenish blue to green) to goshenite (colourless).
The inclusions were characterised in these and in
some other Aquafire samples from the collection
of author MC-V. The orangey yellow to yellowish
green inclusions ranged from a few millimetres to the
width of the entire stone, and were sheet-shaped and
Figure 1: In 2019, aquamarine containing some interesting inclusions was found in Minas Gerais, Brazil. The broken fragments
shown in these images range up to 7 cm long. Photos courtesy of Gems in Gems.
Figure 2: The Aquafire beryls shown here were examined for
this report. The two trilliants (10.29 and 3.26 ct) are cut with
the table parallel to the orangey yellow to yellowish green
inclusions (and perpendicular to the c-axis), while the 5.07 ct
cushion-shaped stone has the table parallel to the c-axis. Gift
of Gems in Gems; photo by B. Williams.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 647
GEM NOTES
Figure 3: This 2.34 ct Aquafire beryl shows bright iridescent
fractures and an orangey yellow appearance due to its
inclusions. Photo by Vicky Rodríguez Garrido.
Figure 4: Internal features in the Aquafire beryl consist of: (a) sheet-like yellowish green inclusions with irregular borders; (b)
orangey yellow platelets displaying thin-film interference colours in a mosaic pattern with six-sided reflective iridescent surfaces;
and (c) dark green platelets and fluid inclusions that are seen here dispersed over a sheet of the orangey yellow mineral.
Photomicrographs by Liviano Soprani (a and b; image width 3.5 mm) and B. Williams (c; image width 3.0 mm).
typically oriented approximately perpendicular to the
c-axis (i.e. parallel to the cleavage direction; Figure
4a). They sometimes displayed a mosaic pattern
with many six-sided reflective iridescent surfaces
that were capable of producing a sunstone-like effect
(e.g. Figure 4b). Associated with the orangey yellow
to yellowish green inclusions were small submillimetre-scale platy crystals with a hexagonal shape
and a transparent dark green appearance (Figure 4c).
These crystals were oriented approximately parallel
to the larger yellow to green inclusions. Fractures
showing rainbow iridescence were locally present
together with the orangey yellow to yellowish green
inclusions. Abundant two-phase fluid inclusions
were also visible in the stones (again, see Figure
4c). Fine acicular features with a brownish orange
appearance were oriented parallel to the c-axis and
probably consisted of hollow tubes filled with epigenetic material (see Figure 2, centre stone).
Raman spectroscopy of the small dark green
inclusions with a Magilabs GemmoRaman-532SG
instrument only yielded spectral features of the beryl
host. The inclusions in two of the stones (5.07 and
10.29 ct) were then analysed in more detail using a
Renishaw inVia Qontor Raman microscope equipped
with a 532 nm laser and a 100× long-working-distance
objective. A confocal setup was used for the analyses
to ensure high spatial resolution. Raman map data
were obtained, and volume imaging and depth
profiling were performed on an orangey yellow
inclusion in the larger stone. For phase identification,
the Raman spectral patterns were compared to
Renishaw’s reference library. Both the orangey yellow
areas and the minute dark green inclusions yielded
Raman spectra consistent with goethite, although not
with complete certainty. In addition, one of the platy
dark green hexagonal-shaped inclusions produced
a mixed pattern consisting of signals indicative of
goethite along with the host beryl. Although the
preliminary identification of goethite is consistent
with the frequent presence of Fe-bearing inclusions
in beryl, to the authors’ knowledge the green colour
shown by some of the inclusions has not been
documented previously for goethite.
Fe-bearing mineral inclusions in aquamarine were
documented by Koivula (2006) in a stone from India
and by Danet et al. (2012) in samples from Madagascar.
Both authors described arrays of flat inclusions—
in some cases dendritic—that were oriented in the
basal plane of the host aquamarine; these produced
aventurescence in the beryl from India. The authors
concluded that the black inclusions were usually
ilmenite, while the red ones were hematite. Beryl of
this type is also known from Brazil, and has been
marketed as ‘Leopard Aquamarine’ (for dark blue
stones with black spots) or ‘Sunstone Aquamarine’
(for light blue gems with lighter-coloured inclusions).
a b c
648 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
Although Aquafire beryl also hosts Fe-rich inclusions, their non-dendritic structure and their orangey
yellow to yellowish green and dark green colouration
make it a new variety of aquamarine. Further studies
are necessary to better characterise the inclusions
mineralogically.
References
Danet, F., Schoor, M., Boulliard, J.-C., Neuville, D.R.,
Beyssac, O. & Bourgoin, V. 2012. Inclusions in
aquamarine from Ambatofotsikely, Madagascar. Gems
& Gemology, 48(3), 205–208, https://doi.org/10.5741/
gems.48.3.205.
Koivula, J.I. 2006. Gem News International: Cuneiform
aquamarine inclusion. Gems & Gemology, 42(1),
70, https://www.gia.edu/gems-gemology/
spring-2006-gem-news-international.
Emerald and Green Beryl from Shaanxi Province, China
In China, emeralds have been mined from two deposits:
(1) Malipo (or Dyakou) in Yunnan Province, since the
late 1980s (Hu & Lu 2019); and (2) Davdar village in
south-western Xinjiang, mainly since 2008 (Cui et al.
2020). Recently, emeralds have come from a new locality
(Figure 5) in central China: the Qinling Mountains in
Zhen’an County, Shaanxi Province, where they are
associated with a W-Be deposit (Dai et al. 2019). In
June 2023, author LP received a parcel consisting of
29 pieces of hexagonal prismatic, translucent, heavily
included, light-to-moderate green crystals from this
locality that weighed 0.07–1.59 g. Eight of them (Figure
6) were selected for analysis at the Antwerp Laboratory
for Gemstone Testing (ALGT). Later, some larger crystals
of higher clarity were reportedly extracted from a deeper
area of the deposit or nearby.
The average hydrostatic SG value for the samples
lacking any matrix material was 2.68. Due to the
abundant inclusions and surface characteristics of
the samples received, it was not possible to obtain an
accurate RI measurement. Raman spectra obtained
with a GemmoRaman-532SG spectrometer revealed
the attached host rock to be mainly quartz, indicating
a hydrothermal origin (Giuliani & Groat 2019). All the
samples were found to contain significant amounts of
oil in surface-reaching fissures, but no dyes or pigments
were detected in the oil. None of them showed a red
or pink reaction under a Chelsea Colour filter, and all
were inert to long- and short-wave UV radiation. All
showed yellow-green and green dichroism when viewed
with a London dichroscope (Figure 7a). Microscopic
examination revealed abundant fractures, and a threephase inclusion was seen in one of the samples (Figure
7b). In addition, some minute dark solids and tube-like
Figure 5: (a) Beryl/emerald crystals from a new deposit in Shaanxi Province are shown embedded in their host rocks. (b) This
assortment of loose emerald crystals (0.2–7.72 g) is also from the new locality in Shaanxi Province. (c) A bluish green emerald
from the new occurrence shows relatively high clarity. Photos reproduced with permission.
a b c
Dr Alessandra Costanzo fga dga
University of Galway, Ireland
Cara Williams fga and Bear Williams fga
Stone Group Laboratories
Jefferson City, Missouri, USA
Dr Marco Campos-Venuti
Gems in Gems, Seville, Spain
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 649
GEM NOTES
Figure 6: These eight beryl crystals from Shaanxi Province were examined for this report. Composite photo by ALGT.
1 (0.16 g)
5 (0.84 g)
2 (0.42 g)
6 (0.31 g)
3 (0.16 g)
7 (0.43 g)
4 (1.27 g)
8 (0.16 g)
inclusions were observed.
The chemical composition of five samples was determined by energy-dispersive X-ray fluorescence (EDXRF)
spectroscopy using a Thermo Scientific ARL Quant’X
instrument. Chromium was below the detection limit,
while significant amounts of V and Fe were found in
all the samples (Table I). Other trace elements included
Cs, Ca, K, Rb and Ga. Ultraviolet-visible-near infrared
(UV-Vis-NIR) spectroscopy of seven specimens showed
strong Fe3+ absorption at 375 nm and Cr3+/V3+ absorptions at about 435 and 605 nm (Figure 8).
It is well known that the green colour of emerald can
come from a mixture of the chromophores Cr, V and
Fe (Hänni 1992). The examined samples from Shaanxi
Province were coloured by both V3+ and Fe3+. While
Figure 7: (a) Viewed
with a dichroscope, the
0.42 g emerald crystal
from Shaanxi Province
shows yellow-green and
green dichroism. (b) A
three-phase inclusion
is present in sample
no. 1, as shown here in
immersion in benzyl
benzoate and magnified
55×. Photomicrographs
by Lirui Peng.
a b
Sample no. 1 2 5 6 7
Element (wt.%)
K 0.28 0.09 0.05 0.13 0.28
Ca 0.27 0.15 0.04 0.11 0.25
V 0.51 0.37 0.35 0.26 0.62
Fe 0.43 0.23 0.16 0.30 0.43
Ga 0.01 bdl bdl 0.01 0.01
Rb 0.01 0.01 bdl 0.01 0.01
Cs 0.19 0.34 0.24 0.23 0.36
* Cr was below the detection limit (bdl; approximately 1 ppmw)
in all analyses.
Table I: EDXRF trace-element composition of beryl/emerald
from Shaanxi Province, China.*
650 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
UV-Vis-NIR Spectra
Absorbance
Wavelength (nm)
2.50
1.50
0
365 465 565 665 765 865 965
H20
958
Fe2+ ± Fe2+–Fe3+
~830
Fe3+
375
Cr3+
680
Cr3+, V3+
605
Cr3+, V3+
~435
Figure 8: UV-Vis-NIR spectra of seven of the beryl/emerald samples show main absorptions at 375 nm due to Fe3+ and at
approximately 435 and 605 nm due to Cr3+ and/or V3+.
1
2
3
4
5
6
7
References
Cui, D., Liao, Z., Qi, L., Zhong, Q. & Zhou, Z. 2020. A
study of emeralds from Davdar, north-western China.
Journal of Gemmology, 37(4), 374–392, https://doi.
org/10.15506/jog.2020.37.4.374.
Dai, H., Wang, D., Liu, L., Huang, F. & Wang, C. 2019.
Metallogenic epoch and metallogenic model of the
Hetaoping W-Be deposit in Zhen’an County, south
Qinling. Acta Geologica Sinica, 93(6), 1342–1358 (in
Chinese with English abstract).
Giuliani, G. & Groat, L.A. 2019. Geology of corundum and
emerald gem deposits: A review. Gems & Gemology,
55(4), 464–489, https://doi.org/10.5741/gems.55.4.464.
Hänni, H.A. 1992. Blue-green emerald from Nigeria (a
consideration of terminology). Australian Gemmologist,
18(1), 16–18.
Hu, Y. & Lu, R. 2019. Unique vanadium-rich emerald from
Malipo, China. Gems & Gemology, 55(3), 338–352,
https://doi.org/10.5741/gems.55.3.338.
Unusual Colour-zoned Emerald
many gemmologists would consider the deeper-coloured
samples to be emerald—and would call the paler crystals
green beryl—ALGT considers Cr as one of the necessary
elements for green colour in emerald, and therefore
would classify the studied specimens as green beryl.
Lirui Peng fga ([email protected])
Antwerp, Belgium
Marc Segers and Mingyue Yang
ALGT, Antwerp, Belgium
Recently, a 3.42 ct green gemstone was submitted to
the Gemmological Certification Services laboratory
for testing. Initial observations showed an unusual
web-like colour distribution (Figure 9). The stone’s
green colour and RI of 1.570–1.575 suggested that it
was an emerald, likely of low iron content. EDXRF
chemical analysis and Raman spectroscopy further
proved it was emerald. UV-Vis-NIR spectroscopy
indicated it had a low Fe content consistent with
a Colombian origin. Testing with long-wave UV
radiation revealed the presence of significant oiling,
supported by prominent oil-related peaks in the
infrared spectrum.
The emerald’s green colour was concentrated in the
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 651
GEM NOTES
Figure 9: Unusual web-like colour concentrations can be
seen through the table of this 3.42 ct emerald. Photo by
A. Duffy.
Figure 10: Viewed table-down along the c-axis direction with
diffused light, areas of green colour can be seen surrounding
colourless, roughly hexagonal zones in the emerald. Photomicrograph by A. Duffy; magnified 15×.
Figure 11: When viewed obliquely to the c-axis, the hexagonal
growth pattern takes the form of sharp, angular zones. Note
the absence of colour at the top of the image, towards the crown
of the stone. Photomicrograph by A. Duffy; magnified 40×.
c-axis
lower (pavilion) part of the stone, while the crown
appeared near-colourless. This was reflected in the
EDXRF trace-element results, which yielded notably
greater Cr and V values for the pavilion (1260 and
740 ppm, respectively) compared to the crown (270
and 150 ppm, respectively). In cross-polarised light, a
typical uniaxial interference figure was seen through
the table, indicating the c-axis was oriented perpendicular to the table. The stone also displayed the expected
reaction with a dichroscope, with the green areas
showing bluish green and yellowish green colouration.
Microscopic examination revealed details of the
unusual colour zoning. In immersion and looking
through the stone table-down (i.e. down the c-axis), a
mottled pattern could be seen, consisting of near-colourless roughly hexagonal columnar-like features outlined
by interstitial green areas (Figure 10). Viewed at an
oblique angle, the hexagonal columns took the form of
green-edged jagged peaks (Figure 11).
Similar colour zoning has been noted previously in
natural emerald (Gübelin & Koivula 2008; Muyal et al.
2015), and was ascribed to a late-stage influx of Cr and
V into the growth environment during crystallisation.
Thus, it appears that the near-colourless hexagonal
columns grew first in a parallel arrangement, and
then conditions changed, favouring crystallisation of
Cr- and V-bearing beryl (emerald) in the interstitial
and surrounding areas.
Despite clearly exhibiting a columnar structure,
the stone did not display the gota de aceite optical
effect that is sometimes associated with Colombian
emeralds. The unusual colour zoning seen here is a
reminder of the dynamic and changeable conditions
under which gems form.
References
Gübelin, E.J. & Koivula, J.I. 2005. Photoatlas of Inclusions
in Gemstones, Vol. 2. Opinio Publishers, Basel,
Switzerland, 829 pp. (see pp. 433–434).
Muyal, J., Renfro, N. & Cooper, A. 2015. Lab Notes:
Colour zoned emerald. Gems & Gemology, 51(3),
314, https://www.gia.edu/gems-gemology/
fall-2015-labnotes-color-zoned-emerald.
Alexander Duffy fga dga
Gemmological Certification Services
London
652 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
Trapiche emeralds from Colombia are fascinating to many
gemmologists and collectors. A notable trapiche emerald
weighing 10.77 ct was recently examined at Guild Gem
Laboratories (Figure 12). Standard gemmological testing
showed properties consistent with those of emerald,
with a uniaxial optic character, spot RI of approximately
1.57 and hydrostatic SG of 2.71. Chemical analysis by
EDXRF spectroscopy revealed a low concentration of
Fe (690 ppmw), high V (1190 ppmw) and low Rb (12
ppmw), which is consistent with values reported for
Colombian emeralds (Saeseaw et al. 2019).
As usual for trapiche stones, this gem was cut as a
cabochon with the basal plane orientated perpendicular
to the c-axis, and it showed a small hexagonal core with
six radiating green arms and dendrites (cf. Pignatelli et
al. 2015). Microscopic observation revealed classic threephase fluid inclusions and black carbonaceous material
from the surrounding black shale. In addition, abundant
transparent striations oriented perpendicular to the sides
of the central hexagon were present in each arm. These
striations were described by Pignatelli et al. (2015) as
bundles of straight dislocations oriented perpendicular
to the {10 0} faces, and they are known to produce
chatoyancy in cabochons cut from the arms of
Colombian trapiche emeralds (e.g. Weldon & McClure
2013; Laurs 2020).
When the emerald was illuminated through either the
top or bottom with a focused light source, a six-pointed
geometric hexagram, or ‘Star of David’ pattern, was
projected on the surface behind the stone (Figure 13).
The pattern was clearly visible only at a certain distance
(around 5 cm) behind the cabochon. When the stone
‘Star of David’ Pattern Produced by a Trapiche Emerald from Colombia
Figure 12: This 10.77 ct trapiche emerald (14.78 × 12.97 × 6.20
mm) exhibits an attractive appearance, but it also proved
capable of yielding an interesting optical effect. Photo by
Kaiyin Deng.
Figure 13: When a focused light source is directed through
the 10.77 ct trapiche emerald parallel to the c-axis, a Star of
David pattern is projected onto the surface behind it. Photo
by Huixin Zhao.
was tilted, the pattern became narrower. Each edge of
the Star of David pattern was oriented perpendicular
to the striations within the corresponding arm of the
trapiche emerald (Figure 14). Thus, the pattern appears
to result from six sharp intersecting chatoyant ‘eyes’ that
are produced by the parallel striations within each arm
of the trapiche emerald.
Although optical effects such as asterism and chatoyancy are normally seen in reflected light when viewing
the dome of cabochon-cut stones (e.g. epiasterism), it is
Figure 14: This diagram shows the relationship between
the orientation of the striations in the arms of the trapiche
emerald and the chatoyant bands (white lines) that are
produced by them. The view is parallel to the c-axis.
Illustration by Xueying Sun.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 653
GEM NOTES
less common to see these phenomena with transmitted
light through the gemstone (i.e. diasterism). This optical
phenomenon would not have been noticed if the Star of
David pattern had not been seen behind the stone while
it was being examined. Such projected diasterism has
only rarely been mentioned in the literature; an interesting example was documented by Killingback (2007) in
a star rose quartz sphere. The trapiche emerald reported
here is unusual in that it contains a high-enough density
of parallel dislocations to produce chatoyancy while also
being transparent enough for the multiple cat’s-eyes to
be transmitted through the stone and manifested in the
hexagram-shaped light pattern.
Xueying Sun, Yujie Gao ([email protected])
and Kaiyin Deng
Guild Gem Laboratories
Shenzhen, China
References
Killingback, H. 2007. Star rose quartz by laser light.
Gems&Jewellery, 16(3), 10–11.
Laurs, B.M. 2020. Gem Notes: A collection of cat’s-eye
emeralds from Colombia. Journal of Gemmology, 37(2),
126–127, https://doi.org/10.15506/jog.2020.37.2.126.
Pignatelli, I., Giuliani, G., Ohnenstetter, D., Agrosì, G.,
Mathieu, S., Morlot, C. & Branquet, Y. 2015. Colombian
trapiche emeralds: Recent advances in understanding
their formation. Gems & Gemology, 51(3), 222–259,
https://doi.org/10.5741/gems.51.3.222.
Saeseaw, S., Renfro, N.D., Palke, A.C., Sun, Z. & McClure,
S.F. 2019. Geographic origin determination of emerald.
Gems & Gemology, 55(4), 614–646, https://doi.
org/10.5741/gems.55.4.614.
Weldon, R. & McClure, S. 2013. Unveiling the cat’s-eye
effect in a 75 ct Colombian emerald pair. https://www.
gia.edu/gia-news-research-unveiling-cats-eye-effectin-colombia-emerald-pair, 12 July, accessed 23 August
2023.
New Production of Rhodizite-Londonite from Manjaka, Madagascar
Since 2016, the renewal and approval of all mining
licences in Madagascar have been blocked, with the
official reason that a new mining law is under study.
This has created significant administrative confusion
in the mining sector there. Nevertheless, in early 2020
some Malagasy government authorities allowed Chinese
companies to undertake ‘parallel’ activities of mining
and collecting lithium ore. This resulted in a new mining
rush taking place at all of Madagascar’s Li-bearing
pegmatite fields by thousands of artisanal miners, with
no security or sanitary control, and disregarding any
pre-existing mining licences. As a by-product of this
pursuit of lithium ore, there has been new production
of pegmatitic gems, mostly tourmaline. In addition,
less-common gem materials have been produced, as
described in this report.
In October 2022, a group of scientists from Masaryk
University (Brno, Czech Republic) and Goethe University (Frankfurt am Main, Germany) visited several
classic mineral and gem localities in the Sahatany Valley
of central Madagascar, during a field trip focusing on
granitic pegmatites organised by author FP. Among the
localities visited was a place known in the literature as
Manjaka (Lacroix 1922), which in recent years has been
referred to by local miners as Sahananana (from the
name of a small village located a few hundred metres
south-east of the deposit). This area has been mined
since the early twentieth century, mainly for small
crystals of vivid red tourmaline. After a long period of
inactivity, in early 2020 many tens of miners (expanding
to more than 200 miners in early 2022) rushed there
to dig for lithium ore. At the time of our visit, about
120 people (miners and their families) were working
the pegmatites in numerous shafts using simple hand
methods (Figures 15–17). During a more recent visit
made by author FP in July 2023, the work was still
going on.
The Sahatany Valley pegmatite field is characterised
by numerous occurrences of Li-enriched, gem-bearing
pegmatites (Pezzotta 2001), occasionally containing
large pockets lined with attractive gem-quality crystals of
multi-coloured elbaite-liddicoatite, morganite, kunzite,
colourless hambergite and yellow rhodizite-londonite
and danburite. In the Manjaka area, two major types of
pegmatites have been recognised (Gadas et al. 2023): (1)
A few east-west-trending dykes, of limited length but up
to about 2 m thick, that are discordant or parallel to the
foliation of the calc-silicate host rocks; and (2) numerous
elongated dykes, from 2 to about 20 cm thick, that are
typically concordant with the host-rock foliation. In the
654 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
Figure 15: An overview of the Manjaka (Sahananana) mining area shows the extent of activity in October 2022, when about 120
people were working the deposit. Photo by M. Novák.
Figure 16: A closer view of the workings illustrates the simple
techniques used by the miners, including primitive windlass
systems. Photos by M. Novák.
Figure 17: Local miners and their families are involved with
producing lithium ore (and gem materials as by-products) in
Madagascar, as shown here at Manjaka. Photo by M. Novák.
first type, dark (black or brown) tourmaline predominates over pink-to-red tourmaline, which occasionally is
found in the central parts of the pegmatites. In the other
type, pink-to-red tourmaline significantly predominates
and locally grows directly from the contact with the host
rock. Associated with this tourmaline are well-formed
isometric crystals of yellow rhodizite-londonite (e.g.
Figure 18a), some of which contain facetable material
(Laurs et al. 2002).
As of July 2023, recent mining activities at Manjaka
have produced about 2 tonnes of lithium ore weekly
(with an average grade of about 30% spodumene),
and so far about 200 tonnes of lithium ore have been
extracted. Although gem-quality rhodizite-londonite
is very rare at the locality, the amount of pegmatitic
rock mined for lithium ore is so large that during the
past two years there has been a near-constant supply
of gem rough, which is mostly faceted and traded at
the local market in Antsirabe. Also produced are significant amounts of low-grade red tourmaline, which is
mostly traded by West African gem dealers to the Indian
market.
The total recent production of rhodizite-londonite is
difficult to estimate, but is probably on the order of a few
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 655
GEM NOTES
Figure 18: Exceptional examples of rhodizite-londonite recently produced from Manjaka include (a) this 65 g crystal (4.1 cm in
maximum dimension) and (b) this 48 ct cushion-cut gemstone. Both specimens are in the collection of the MIM Museum
(Beirut, Lebanon). Photos by Louis Dominique Bayle.
a b
hundred grams of good-quality gem rough. In addition
to material from Manjaka—which ranges from very light
yellow to vivid yellow—parcels of rhodizite-londonite
may contain pieces from other deposits, such as Antsongombato, Manapa and Tetezantsio (which are also being
mined for lithium ore). The material from these localities
cannot be distinguished, with the exception of the pale
bluish to greenish rhodizite-londonite that is exclusive
to Tetezantsio. Some attractive faceted stones have been
cut from the recent production, including vivid yellow,
eye-clean gems weighing up to several carats (very rarely
over 10 ct) that have been traded in the local market
since 2021. Although gem-quality rhodizite-londonite is
quite rare, the mining boom for lithium ore has increased
its availability to levels never seen before, and some
exceptional specimens have occasionally been produced,
including well-formed crystals exceeding 3 cm in
diameter and faceted stones of nearly 50 ct (Figure 18).
Dr Milan Novák ([email protected])
Masaryk University
Brno, Czech Republic
Dr Federico Pezzotta
Mineralogical Collection Professionals
Milan, Italy
References
Gadas, P., Novák, M., Vašinová Galiová, M. & Pezzotta,
F. 2023. Chemical composition of tourmalines
from the Manjaka pegmatite and its exocontact,
Sahatany Valley, Madagascar. Journal of Geosciences
(in press).
Lacroix, A. 1922. Minéralogie de Madagascar. Tome I:
Géologie, Minéralogie Descriptive. Augustin Challamel,
Paris, France, xvi+624 pp.
Laurs, B.M., Pezzotta, F., Simmons, W.B., Falster, A.U. &
Muhlmeister, S. 2002. Rhodizite-londonite from the
Antsongombato pegmatite, central Madagascar.
Gems & Gemology, 38(4), 326–339, https://doi.org/
10.5741/gems.38.4.326.
Pezzotta, F. 2001. Madagascar: A Mineral and Gemstone
Paradise. extraLapis English No. 1, Lapis International,
East Hampton, Connecticut, USA, 97 pp.
Sphalerite from Balmat, New York, USA
Sphalerite (ZnS) is the most important zinc ore and
is also known as zinc blende. It commonly contains
Fe, which causes it to appear dark and opaque, but
specimens with low Fe content can appear transparent
in near-colourless, yellow, orange, red, brown or green
(Bradshaw 2015). Sphalerite has a Mohs hardness of
3½–4 and perfect dodecahedral cleavage, so it is not
well suited for jewellery, but it makes an attractive
collector’s stone that shows high dispersion. The
main source of gem-quality sphalerite is Spain (Aliva
mine; no longer active), and other localities include
Bulgaria (Rhodope Mountains), Canada (Mt St Hilaire
656 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
in Québec), Mexico (Sonora) and the USA (Franklin,
New Jersey; Bradshaw 2015).
Over the past several decades, economically important
zinc deposits of the Balmat-Edwards zinc mining
district in St Lawrence County in the north-west Adirondack Mountains of New York, USA, have occasionally
produced sphalerite as well-formed crystals and rare gem
rough (Smith & Pressler 1998). The ore bodies are hosted
by Proterozoic siliceous dolomitic marble that was
metamorphosed during the Grenvillian Orogeny about
1.1 billion years ago, and the mineralisation has been
categorised as a massive stratiform sulphide type of
sedimentary exhalative deposit (deLorraine & Johnson 1997).
Deposits in the Balmat District were important
sources of zinc from 1903 to 2005, and recently all of
the historic mines there (i.e. Balmat No. 2, 3 and 4
shafts) were purchased by Titan Mining Corporation
and renamed collectively as the Empire State mine. Zinc
mining resumed in 2018 at the former Balmat No. 4
shaft, where crystallised cavities were encountered at the
3,800-foot level in the Mud Pond orebody that produced
attractive specimens of calcite, halite, pyrrhotite, quartz
and sphalerite (Chamberlain & Walter 2020). Since
then, several more pockets containing specimen- and
Figure 19: This 9.37 ct sphalerite came from the Empire State
mine (former Balmat No. 4 shaft) in 2019. It was faceted by
Jay Medici and is the largest cut sphalerite from New York.
Dylan Stolowitz collection; photo by Rudolf Van Dommele.
Figure 20: Faceted by Jason Baskin from material mined in
2022, this sphalerite from the Empire State mine weighs 6.49 ct.
The diffused lighting emphasises the body colour and not the
dispersion. Courtesy of Rocko Minerals; photo by Jeff Scovil.
gem-grade sphalerite have been found. According to
Dylan Stolowitz (Green Mountain Minerals, Beacon,
New York), starting in November 2019 additional finds
occurred at the 3,800-foot level of the Mud Pond ore
body. Over an approximately three-month period,
several hundred sphalerite crystals averaging 1 cm (and
up to 5+ cm) were recovered, but a large percentage
were damaged. Although many of the crystals were
facetable, most were colour zoned with dark brown
cores. Notably, a small amount of gem-quality ‘sulphur
yellow’ material was found in a separate pocket on this
same level (Figure 19).
Stolowitz reported that, most recently in 2022–2023,
pockets containing well-crystallised sphalerite were
found at the 3,800 and 4,050 foot levels. Several worldclass specimens were recovered on a matrix of quartz
and calcite. The colour of the sphalerite included yellow,
orange and red, and some fine gemstones have been cut
(e.g. Figure 20).
Continued zinc exploitation at the Empire State
mine is expected to yield additional finds of specimenand gem-quality sphalerite in the future.
Brendan M. Laurs fga
References
Bradshaw, J. 2015. Gem Notes: Sphalerite. GemGuide, 34(2), 11–12.
Chamberlain, S.C. & Walter, M.R. 2020. Collector’s Note:
Balmat mining district update, St. Lawrence County,
New York. Rocks & Minerals, 95(5), 463–466, https://
doi.org/10.1080/00357529.2020.1744100.
deLorraine, W.F. & Johnson, J. 1997. Geologic field guide to
the Balmat zinc mine, St. Lawrence County, New York.
In: Rayne, T.W., Bailey, D.G. & Tewksbury, B.J. (eds),
Field Trip Guide for the 69th Annual Meeting of the
New York State Geological Association, 85–116.
Smith, A.E. & Pressler, C.D. 1998. A 1946 find of gem
sphalerite crystals at the Balmat zinc mine, St.
Lawrence County, New York. Rocks & Minerals, 73(6),
404–408, https://doi.org/10.1080/00357529809603080.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 657
GEM NOTES
Nigeria is an important producer of gem tourmaline,
from both primary and secondary deposits associated
with granitic pegmatites. The mining areas are distributed across a wide region extending from south-western
to east-central Nigeria, mainly in the states of Oyo, Osun,
Nasarawa and Kaduna (Olade 2021). Recently, attractive
gem tourmaline entered the market from a new deposit
that is reportedly situated in the Calabar region of southeastern Nigeria. Calabar is located in Cross River State
near the border with Cameroon, and has not been previously reported as a commercial source of gem tourmaline
to this author’s knowledge. However, tourmaline-bearing
pegmatites are widespread in this region, where they are
hosted by basement rocks of the Oban massif and Obudu
plateau (Ekwueme & Matheis 1995). Oden et al. (2011)
reported that in the past, local people have mined tin,
tourmaline and beryl from the Iwuru and Akwa-Ibami
areas of the western Oban massif.
During the February 2023 Tucson gem shows, gem
cutter John D. Dyer (John Dyer & Co., North Oaks,
Minnesota, USA) obtained a parcel of rough tourmaline from the Calabar region that weighed 470 g. It
consisted of broken pieces that appeared to have been
cobbed from larger crystals in order to obtain cleaner
sections for cutting (Figure 21). Most of the tourmaline
was yellowish green to bluish green, with some pink
and orangey pink pieces. The rough material ranged
from approximately 2 to 7 g, and had an average weight
of 3.65 g.
As of July 2023, Dyer had cut 43 stones weighing a
total of 150 carats (i.e. 1.75–11.12 ct, mostly in the 2–4
ct range). He reported that the cutting yield was poorer
than typically obtained from tourmaline, due mainly to
Tourmaline from Calabar, Nigeria
Figure 21: The rough Calabar tourmaline shown here ranges
from approximately 2 to 7 g. Photo by John D. Dyer.
Figure 22: Two pieces of green Calabar tourmaline weighing approximately 5–6 g are shown in different orientations to
demonstrate variations in their yellowish green to bluish green colour appearance depending on the viewing direction. The
yellowish green colour is seen down the c-axis. Photos by John D. Dyer.
the clarity and shape of the rough. The broken pieces
were less well suited for cutting gemstones than the
typical triangular or pseudo-hexagonal cross-sections of
tourmaline crystals. In addition, the c-axis of the green
material tended to show an olive hue that, although
not over dark, was less appealing (Figure 22). Since
the broken pieces tended to be wider on the c-axis,
orienting the rough to avoid face-up olive colouration
also reduced the yield.
Despite the challenges of cutting the material, the
finished gemstones display vibrant and attractive colouration (e.g. Figure 23). Dyer reported that there are no
significant grey modifiers, resulting in bright hues
showing different variations of yellowish green to bluish
green and ‘seafoam’ colours. The pink stones range
a b
658 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
from deep pink to a paler pink or orangey pink, similar
to morganite. The attractive appearance and range of
colours shown by Calabar tourmaline make it a welcome
addition to the gem trade.
Brendan M. Laurs fga
Figure 23: This assortment of faceted stones (1.86–11.12 ct)
shows the range of colour of Calabar tourmaline. Courtesy
of John Dyer Gems; composite photo by Ozzie Campos and
Rosiane Pereira.
References
Ekwueme, B.N. & Matheis, G.G. 1995. Geochemistry and
economic value of pegmatites in the Precambrian
basement of south-east Nigeria. In: Srivastava, R.K. &
Chandra, R. (eds), Magmatism in Relation to Diverse
Tectonic Settings. A.A. Balkema, Rotterdam,
The Netherlands, 375–392.
Oden, M.I., Igonor, E.E. & Ekwere, S.J. 2011. A comparative
study of REE geochemistry in Precambrian pegmatites
and associated host rocks from western Oban massif,
SE – Nigeria. Global Journal of Pure and Applied
Sciences, 17(2), 197–208.
Olade, M.A. 2021. Gemstones of Nigeria: An overview of
their geological occurrence, provenance and origin.
Achievers Journal of Scientific Research, 3(1), 1–22.
Faceted Sapphire Coloured Blue by a Polymer Coating
TREATMENTS
Recently, a ring was submitted to Guild Gem Laboratories containing a 6.81 ct cushion-cut blue sapphire
flanked by triangular colourless diamonds (Figure
24). The colour of the sapphire was quite attractive,
showing moderate blue saturation with a light tone.
Its RI was 1.762–1.770 (birefringence 0.008), which is
consistent with corundum. Microscopic examination
revealed colourless and transparent prismatic inclusions,
which were identified as apatite by Raman spectroscopy.
Blurred blue colour zoning was also observed, along with
an expanded discoid fracture, which provided evidence
of thermal enhancement. Combined with a chalky blue
fluorescence reaction to short-wave UV radiation, the
stone appeared to be a heated blue sapphire.
UV-Vis-NIR spectroscopy of the sapphire, however,
yielded unexpected results (Figure 25). A prominent
broad band was centred at 580 nm, along with a sharp
peak at 385 nm, but none of the expected features
related to iron or Fe2+–Ti4+ intervalence charge
transfer were present. The reason for this became
clear with close microscopic inspection of the stone’s
surface, which showed evidence of a coating that had
locally chipped off the pavilion near the girdle (Figure
26). The edges of the coating displayed uneven blue
colour distribution, and in reflected light we could see
a lower lustre for the coated areas compared to the
underlying sapphire.
Figure 24: The 6.81 ct sapphire in this ring exhibits an
attractive blue hue showing moderate saturation and a light
tone. Photo by Huixin Zhao.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 659
GEM NOTES
Figure 25: The UV-Vis-NIR spectrum of the 6.81 ct sample
shows anomalous features compared to those typically recorded
for blue sapphire.
Figure 26: Microscopic examination of the sapphire reveals a blue coating on the pavilion that is locally chipped below the girdle,
on both sides of the stone. Photomicrographs by Huixin Zhao; image width 7.35 mm
Figure 27: (a) The FTIR spectrum of the sapphire displays features associated with a polymer coating at 2853, 2871, 2926, 2955,
3026 and 3060 cm–1. (b) Raman spectroscopy of the coating shows two prominent peaks at 1253 and 1405 cm–1, also associated
with a polymer.
FTIR Spectrum
Absorbance
Wavenumber (cm-1)
2600 2700 2800 2900 3000 3100 3200 3300 3400 3500
2853
2871
3026
2955
2926
3060
Corundum
3163
Raman Spectrum
Intensity
Raman Shift (cm-1)
200 400 600 800 1000 1200 1400
1253
1405
a b
Fourier-transform infrared (FTIR) spectroscopy
recorded aspects consistent with corundum, but also
revealed prominent features at 2853, 2871, 2926, 2955,
3026 and 3060 cm–1 (Figure 27a) that have been attributed to a polymer coating (Lai 2017). In addition,
confocal Raman spectroscopy of the coating showed
two prominent peaks at 1253 and 1405 cm–1 (Figure
27b), consistent with a polymer; the one at 1253 cm–1 is
related to epoxide vibrations (Vašková & Křesálek 2011).
Since the sapphire had no surface-reaching fractures
or fissures, the polymer-related features in the spectra
must have been due to the coating rather than a filler
(i.e. a substance used for clarity enhancement, as is
commonly encountered in emerald and aquamarine).
Thus, we identified the blue gemstone in the ring
as a heated sapphire with a coloured polymer coating.
Although blue sapphires are commonly heated to
improve their colour, coating treatments are rarely
seen on gem corundum, with only a few cases having
UV-Vis-NIR Spectra
Absorbance
Wavelength (nm)
580
6.81 ct sample
Blue sapphire
385
300 400 500 600 700 800 900 1000
Fe2+-Ti4+ and Fe2+–Fe3+
580, 742 and 765
Fe3+
388
Fe3+–Fe3+
450
660 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
GEM NOTES
been reported (e.g. Choudhary 2013; Schneider & Jasso
2019). Such coatings are easy to detect as long as one
remembers to check for them.
References
Choudhary, G. 2013. Gem News International: Corundum
carving coated with colored polymer. Gems &
Gemology, 49(3), 184–185.
Lai, L.T.-A. 2017. Gem News International: Coated beryl
imitating emerald. Gems & Gemology, 53(4), 481–482.
Schneider, V. & Jasso, J. 2019. Lab Notes: Cobalt-coated
sapphire. Gems & Gemology, 55(3), 421–422.
Vašková, H. & Křesálek, V. 2011. Raman spectroscopy of
epoxy resin crosslinking. 13th WSEAS International
Conference on Automation Control, Modeling &
Simulation (ACMOS’11), Lanzarote, Canary Islands,
Spain, 27–29 May, 357–361.
Mystery Pendant Watch Made by Fabergé?
MISCELLANEOUS
While conducting an appraisal of an estate containing
some stunning pieces of jewellery, this author
encountered an intriguing pendant watch (Figure
28). The case contained multicoloured enamelling,
tiny rose-cut diamonds and a row of channel-set blue
sapphires (Figure 29). The overall shape and winding
mechanism were unusual: the watch was wound by
rotating the lower half of the case back and forth
just like a stem and crown on a wristwatch. The
time could be set by pushing a tiny button and again
turning the lower half of the case.
Inspection of the watch dial (Figure 30a) revealed a
hallmark of Cyrillic lettering (ФAБEPЖE; Figure 30b)
that translates to ‘Fabergé’. Further examination for
Russian hallmarks yielded the Cyrillic initials КФ (for
Karl Fabergé) and the initials HW (for Henrik Wigstrom)
on the top bail loop (Figure 31). Wigstrom became the
senior ‘workmaster’ for Fabergé in 1903 (Booth 1996),
and he presided over the Fabergé workshops during
their heyday when thousands of items were produced.
Strangely, there were no metal stamps on the opposite
side of the bail loop. The pendant watch appeared to be
made with platinum, which was confirmed with X-ray
Figure 28: This pendant watch (34 × 19 mm) was examined
as part of an estate appraisal and is suggestive of Fabergé
work. Photo by C. A. Lynch.
Figure 29: The case of the pendant watch is decorated
with enamel, rose-cut diamonds and sapphires. Photo by
C. A. Lynch.
Yujie Gao, Tiantian Huang
and Yanhua Ni
Guild Gem Laboratories
Shenzhen, China
Chen Zheng
Shenzhen Institute of Technology, China
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 661
GEM NOTES
References
Booth, J. 1996. The Art of Fabergé. Wellfleet Press, Secaucus,
New Jersey, USA, 192 pp. (see p. 57).
Whetstone, W.B., Niklewicz, D.V. & Matula, L.L. 2010.
World Hallmarks, Volume I: Europe, 19th to 21st
Centuries, 2nd edn. Hallmark Research Institute,
396 pp. (see p. 246).
fluorescence analysis. Later, a possible reason for the
missing metal stamps was discovered: there were no
hallmarks for platinum in Russia until 1927 (Whetstone
et al. 2010).
Upon request, the estate owners provided documentation for the pendant watch in the form of a typewritten
letter from the 1960s. The letter detailed how the watch
had been gifted to the family and noted its long-standing
presence in their lineage. The information appeared
credible, adding to the perceived authenticity of the
watch as an important Fabergé piece.
However, to confirm this, the author consulted with
three Fabergé experts: one who works at a distinguished
Figure 30: The dial of the
watch (a) contains a stamp
which, at 50× magnification
(b), can be discerned as
Cyrillic lettering that translates
to ‘Fabergé’. Photos by
C. A. Lynch.
a b
auction house in London, one in Russia, and another
who is a highly regarded watch expert in Europe (all of
whom wish to remain anonymous). They were provided
with a detailed description and photographs of the
pendant watch, and one of the experts also examined
it in person. Interestingly, they all concluded that the
pendant watch was ‘highly unlikely’ to be made by
Fabergé because the quality of craftsmanship did not
match that of a genuine Fabergé piece. They thought
it to be Swiss-made in around 1907–1912, when the
first ‘ball’ winding movements were made. They also
suggested that the dial and loop bail were replacements
added after the watch’s original creation. With closer
examination (again, see Figures 29, 30b and 31), it is
possible to see what the experts were referring to. For
example, in the guilloché enamelling on the case, the
linear patterns are good but not of the perfection seen
on authentic Fabergé pieces. In addition, the dial of
the watch is dull looking rather than showing bright
enamel work, and the lettering of the name ‘Fabergé’ is
crudely incised into the dial, as opposed to the beautiful
black enamel script typically seen on authentic Faberge
pieces.
Although this pendant watch was most likely not
manufactured by Fabergé, it is still a fascinating piece
and was nevertheless a joy to encounter during an
appraisal of this estate.
Craig A. Lynch ([email protected])
Ouellet & Lynch Appraisal Services
Phoenix, Arizona, USA
Figure 31: The top bail of the pendant watch carries the
stamped letters КФ and HW—presumably for Karl Fabergé
and Henrik Wigstrom, respectively. Photomicrograph by
C. A. Lynch, magnified 70×.
FEATURE ARTICLE
662 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Banjarmasin Diamond:
War Booty from Borneo
in Amsterdam
Suzanne van Leeuwen and J. C. (Hanco) Zwaan
ABSTRACT: The 38.23 ct Banjarmasin diamond in the collection of the Rijksmuseum in Amsterdam
plays a questionable role in the history of the Dutch occupation of southern Borneo. Confiscated from
the Sultanate of Banjarmasin, the original 70+ ct rough diamond arrived in the Netherlands in 1862.
This marked the beginning of a 40-year-long political debate on the fate of this former piece of state
regalia, as well as consideration of whether or not to cut and sell it. It was eventually faceted in 1870,
but efforts to sell it were unsuccessful, and in 1902 it was finally transferred to the Rijksmuseum as a
permanent loan from the Ministry of Colonies. Past publications have focused mainly on the colonial
history of the diamond, and its properties have not been studied in detail until now. As one of the
few large diamonds found in the alluvial deposits of Kalimantan, the results of this study contribute
to the recognition of Borneo as an historically small but important diamond source.
The Journal of Gemmology, 38(7), 2023, pp. 662–677, https://doi.org/10.15506/JoG.2023.38.7.662
© 2023 Gem-A (The Gemmological Association of Great Britain)
The Banjarmasin diamond (Figure 1) is one
of the largest diamonds found in southern
Borneo (i.e. today’s South Kalimantan,
Indonesia). It has been in the collection of
the Rijksmuseum in Amsterdam since 1902 and is the
only unset cut gemstone on permanent display there.
It remains a symbol of the controversial history of
Dutch colonial rule in this part of modern Indonesia.
In its original rough octahedral form, the diamond
was considered to have great personal meaning to
Sultan Adam Al-Watsiq Billah (Figure 2) and his
family (Müller 1839–1844, 1857). The death of the
sultan marked the beginning of the Banjarmasin War
(1859–1864), a conflict over succession during which
the Dutch colonial government decided to dissolve
the century-old sultanate (van Rees 1865a, b; Stutje
2022a, b). The diamond and other ‘voluntarily’ ceded
regalia were sent to the Governor-General of Batavia
(Jakarta) in June 1860 and, for unknown reasons, the
diamond was sent to Amsterdam in December 1861.1
When the diamond arrived in the Netherlands
aboard the war steamer Zr. Ms. Ardjoeno four months
later, it merited special mention in local newspapers,
Figure 1: The Banjarmasin diamond (38.23 ct; approximately
21.86 × 17.37 × 13.86 mm) was cut from a 70+ ct octahedral
crystal that was confiscated from the Sultanate of
Banjarmasin in 1860 and reportedly came from southern
Borneo. It currently resides in the Rijksmuseum, Amsterdam
(inv. no. NG-C-2000-3), where it is on permanent display.
Photo by J. C. Zwaan.
and its value was estimated at 400,000 guilders
(Anonymous 1862).2 In the meantime, the Dutch
government was not sure what to do with this rough
diamond. Plans to offer it to King William III of the
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 663
1 The other regalia were transferred to the Royal Batavian Society of Art and Sciences as ‘archaeological rarities’. They were listed in
an 1868 catalogue (Norman 1868, pp. 95–98) and are now part of the collection of the National Museum of Indonesia in Jakarta
(Stutje 2022a, b).
2 Equivalent to a current value of about EUR4.5 million.
3 As reported in The Hague, National Archives (NL-HaNA), Ministry of Colonies 1850–1900, accession number 2.10.02, inv. no. 1158,
10 March 1862, no. 6, minutes 10-6, p. 4. In the accompanying minutes and correspondence between the Minister of the Colonies
and the Governor-General of Batavia, the Koh-i-Noor diamond was briefly mentioned in comparison with the Banjarmasin diamond.
The Koh-i-Noor was ‘a feat of the British Indian Army’ (eene hulde van ‘t Brits-Ind. Leger) and therefore was placed under the state
regalia. According to the Dutch government, the same applied to the way the Banjarmasin diamond was acquired.
4 Indicated in a letter from the Minister of Internal Affairs to the Minister of the Colonies (NL-HaNA, Ministry of Colonies 1850–1900,
accession number 2.10.02, inv. no. 1272, 3 December 1862, no. 23); see also Stutje (2022a, p. 9).
Figure 2: Sultan Adam Al-Watsiq Billah (1782–1857) owned
the original rough Banjarmasin diamond. His death precipitated
the war that resulted in the transfer of the diamond to
the Dutch colonial government. Portrait of Sultan Adam
Al-Watsiq Billah by Auguste van Pers, circa 1844. Leiden
University Libraries, Collection of the Royal Netherlands Institute
of Southeast Asian and Caribbean Studies (inv. no. 36A143).
Netherlands (1817–1890), either as a personal gift or as
part of the state regalia to be placed in the coronation
crown, fell through. One reason was that the cutting
costs were deemed too high.3 Then the diamond was
offered to the Museum of Natural History in Leiden,
but they declined because it did not fit into their collection and they could not properly secure it.4 Between
1869 and 1898, three attempts to sell it failed, first in
its rough state and later as a cut stone. In August 1902,
the Banjarmasin diamond was finally transferred to the
Rijksmuseum as a permanent loan from the Ministry
of Colonies. The government of the Netherlands is still
the official owner today (Stutje 2022b).
Since 2019, the Banjarmasin diamond has been one
of the objects under discussion in a research project
focusing on the fate of colonial objects in Dutch
museum collections. In March 2022, the Rijksmuseum, in collaboration with the NIOD Institute for
War, Holocaust and Genocide Studies, and the National
Museum of World Cultures, presented the results of this
research in an initiative titled ‘Pilotproject Provenance
Research on Objects of the Colonial Era’ (PPROCE;
Stutje 2022a, b). With possible restitution claims in
mind, the project aims to ‘develop a research methodology and make recommendations for the organisation
and policy surrounding provenance research into
colonial collections’ (for further information, see https://
www.niod.nl/en/projects/pilotproject-provenanceresearch-objects-colonial-era-pproce). The Dutch
government can use, share and supplement this information in cooperation with foreign governments in case
of future restitution claims. The Banjarmasin diamond
may become the subject of one of these claims.
Prior to the PPROCE project, much was written on
the history of this famous diamond (Brus 1987a, p.
38; Brus 1987b, p. 12; Akkerman 1989; Brus 1989, p.
36; Bari & Sautter 2001, pp. 96–101; Zandvliet 2002,
pp. 302–305; Fleet 2005, p. 27; Balfour 2009, pp.
44–45; Drieënhuizen 2017), but a gemmological study
had never been conducted. The diamond is not only
important for its role in colonial history but also from
a material point of view, as it is one of the few historical examples of large diamonds found in Borneo. In
addition, the way the Banjarmasin diamond looked
before and after it was cut greatly affected its (historic)
value and the way it was treated by the Dutch government. The first part of the present article focuses on
sources that describe the rough diamond and the cut
gem. Until recently it was unknown when, where and
by whom the diamond was cut, but the PPROCE project
FEATURE ARTICLE
664 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
yielded valuable new information. The second part of
this article then focuses on the stone’s gemmological
properties and their consistency with the assumed Borneo
origin of the Banjarmasin diamond.
HISTORY
Borneo Diamonds
The diamond deposits of Borneo are, together with the
Indian deposits, the earliest worked diamond mines in
the world. On the island, diamonds have been found
at two main localities: the Martapura area of South
Kalimantan and the Landak District of West Kalimantan
(Spencer et al. 1988; see also Figure 3). The Dutch first
came into contact with diamonds from Borneo in the
early seventeenth century (Content 2020). Following
in the footsteps of Chinese and Portuguese traders, the
Dutch East India Company (Verenigde Oostindische
Compagnie or VOC) brought back a small quantity of
these diamonds from their first voyage to Asia in 1604
(Ikuko 2010). They acquired the stones from Succadana
(or Sukadana), a diamond-trading centre in western
Borneo, where both the VOC and the British East
India Company established a trading post (‘factory’)
soon after (Ogden 2005, 2018). While the British East
India Company focused on the Indian diamond mines,
the Dutch traders purchased 400–500 carats of rough
Kalimantan diamonds yearly between 1610 and 1615.
In 1620, they sent more than 1,000 ct of diamonds back
to Amsterdam.5
Figure 3: This map of the Banjarmasin–Martapura region of
South Kalimantan shows the location of the diamond mining
areas of Karang-intan and Goenong Lawak. The inset image
(adapted from Wikimedia Commons) shows the positions of
the two main diamond-mining regions on the island of Borneo.
N N
5 km
200 km
5 See Ikuko (2010), pp. 169–172. After 1620, the VOC ventured into India, where it purchased small quantities of diamonds from
Kollur, the Coromandel Coast and Surat. After the 1660s, the Dutch diamond trade with India started to decline, and although the
Dutch continued to import Indian diamonds, by the eighteenth century the trade was no longer significant (see Ikuko 2010, p. 183).
Landak
Sabah
Sarawak
South China Sea
Makassar Strait
Java Sea
East
Kalimantan
North
Kalimantan
West
Kalimantan
Central
Kalimantan
Banjarmasin-Martapura
South
Kalimantan
Sukadana
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 665
Figure 4: This map of the Banjermassing (Banjarmasin) and Martapoera (Martapura) areas appeared in a book by Müller
(1839–1844; on p. 590 of the downloadable PDF file), and covers approximately the same area shown in Figure 3. The diamond
localities of Karang-intan and Goenong Lawak are indicated by the red and blue arrows, respectively.
The Rough Banjarmasin Diamond
In September 1829, an unnamed Dutch resident of the
town of Banjarmasin travelled upstream to Martapura
(Figure 4) to visit the official residence, or kraton, of the
Sultanate of Banjarmasin and the diamond quarries in
that area.6 The detailed account of his journey describes
a moonlit trip on a narrow boat with 30 rowers that
took him and his fellow travellers inland with the help
of the incoming tide (Anonymous 1829). After arriving
in Martapura the next morning, they were taken to the
diamond quarries, where they saw ‘yellow clay’ being
washed in wooden troughs/basins in search of diamonds
(Figure 5), still a familiar sight in modern Martapura.7
The next day, the group visited Sultan Adam who, for
the occasion, showed them the biggest ‘brilliant’ ever
found in the open-pit mines of this region.8 Reportedly,
a narrow golden band enclosed a 77 ct rough diamond
that the sultan would wear on a simple black cord
around his neck during festivities (Anonymous 1829).
This account is the earliest of several nineteenth-century sources describing a diamond in the possession of
Sultan Adam that seem to refer to the rough Banjarmasin. Other descriptions were published in newspapers
and in travel accounts of scientists and explorers visiting
the sultanate (Anonymous 1833; Korthals 1836, 1837;
Anonymous 1838; Müller 1839–1844; Teenstra 1852a,
pp. 442–452; van Rees 1865a, p. 28). Some details vary in
the accounts prior to 1848, including the weight, but we
believe all these refer to one and the same diamond, the
Banjarmasin. However, these sources must be used with
some caution because the Banjarmasin was not the only
large diamond owned by the royal family.9 Publications
6 Other diamond quarries were located at Goenong Lawak to the south of Martapura (Figure 4, blue arrow). This area corresponds
to the modern Cempaka diamond fields in the Martapura region.
7 This ‘yellow clay’ refers to the layer above the quartz-rich conglomerate that contained most of the diamonds. For a detailed historic
description of the diamond mining along the river, see Schwaner (1853, pp. 61–69).
8 The term brilliant was used frequently in nineteenth-century Dutch sources to describe diamonds in general. 9 In preparing this article, preliminary information came to light that perhaps more large Borneo diamonds found their way to the
Netherlands via Jakarta in this period. Whether they have a direct relation to the Sultanate of Banjarmasin remains to be investigated.
FEATURE ARTICLE
666 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 5: Local inhabitants search for
diamonds in the Martapura area, as depicted
in J. C. Rappard’s Delving for Diamonds Along
the Sungai Lawak River. Colour lithograph
from Perelaer (1888, see plate between pp. 132
and 133).
after 1848, for example, mention a (rough) diamond
larger than 100 ct (Bleckmann 1850; Teenstra 1852b,
p. 831). W. A. van Rees, a former major in the Dutch
colonial army, also mentioned a 120 ct diamond as part
of the regalia (van Rees 1865a, p. 28). In a region that,
in the middle of the nineteenth century, apparently still
regularly produced diamonds above 5 ct (Müller 1843,
p. 13)10, a regular-shaped octahedron weighing 70+ ct
was still exceptional and one of the reasons why it is
described as the sultan’s most prized possession (Müller
1839–1844, 1857; Zandvliet 2002, pp. 302–305).11 The
fact that this diamond was mentioned in numerous
independent sources, despite discrepancies in the colour
of the cord or the exact weight, illustrates its importance.
Oral descriptions, non-standardised diamond weights
and eyewitness accounts of people with no diamond
expertise help explain some of the inconsistencies. That
being said, because no drawings or photographs of the
diamond are known to exist before 1898, these eyewitness accounts are a valuable source of information about
the appearance of the rough diamond.
The first description to mention the shape of the rough
diamond was written by German zoologist Salomon
Müller (1804–1836).12 In the 1820s and 1830s, he and
a group of other European naturalists travelled through
the Dutch East Indies on behalf of the ‘Committee for
Natural History of the Netherlands Indies’ to collect
specimens of local flora and fauna (Weber 2019). In
1836, his last stop before returning to the Netherlands
was the south-east part of Borneo, where he and two
colleagues spent 4½ months. A few days after their
arrival in the town of Banjarmasin, they travelled
upstream to Martapura and visited Sultan Adam. Müller
was intrigued by the dilapidated state of the residence
and, at the same time, the portable wealth that was
displayed by the royal family (Müller 1839–1844, pp.
419–420; Müller 1857, pp. 268–269). Around his neck
the sultan wore two pieces of jewellery, a gold medal set
with diamonds and an almost regular octahedron that
MÜller reported weighing 77 ct which was suspended
on a simple cord.13
One of the colleagues accompanying Müller in
Borneo was the Dutch botanist P. W. Korthals (1802–
1897). Previously unpublished parts of his diary from
August 1836 and a short article from a year later describe
his visit with Sultan Adam (Korthals 1836, 1837).
10 Officially, diamonds above 5 ct had to be ceded to the sultan and his family for a small compensation. 11 According to Max Bauer (1904, p. 219), the Malay considered regular octahedra as ‘the perfect stones’ because they required little
or no cutting.
12 In past publications, this account was often cited as the first nineteenth-century source mentioning the Banjarmasin diamond. 13 The gold medal was presented to Sultan Adam by Governor-General of the Dutch East Indies, J. van den Bosch (1780–1844), as a
token of their alliance. The medal was inscribed in Malaysian and Dutch: Het Nederlandsche Gouvernement aan zijnen getrouwen
bondgenoot den Sultan van Banjermassing (‘The Dutch Government to its faithful ally the Sultan of Banjermassing’. See Müller
1839–1844, p. 420; Müller 1857, p. 269).
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 667
Korthals’ diary describes both the sultan’s clothes and
the diamond in detail. He mentioned that the sultan
was a man of ‘normal’ size, tastefully dressed in green
silk trousers, with gold galloon on the seams and a
white vest set with diamond buttons increasing in size
near the neckline. His yellow headscarf was ‘folded
curiously with at least a dozen points’ (see Figure 2).
14
He wore multiple finger rings set with gemstones, and
diamond studs in his ears, and Korthals also described
the gold medal set with diamonds.15 The sultan’s eldest
son and heir to the throne, Abdul Rachman (1825–
1852), was sitting next to him on a chair covered with
yellow silk. He wore a yellow headscarf with a silver
galloon trim, white trousers and a black velvet samaar
(tabard) decorated with flowers in gold thread. Korthals
described three diamonds aan de hals (on the neck) of
the sultan moeda (sultan’s son), one of which was a
40 ct cut diamond.16
After ‘lukewarm and weak tea accompanied with
local pastry’, Sultan Adam showed Korthals and his
colleagues the diamond, reported as weighing 76 ct
(Korthals 1836).17 The fairly regular octahedral-shaped
diamond was colourless, and through one of its faces
Korthals spotted some black dots. Colour-wise he called
the stone ‘pure’. He further wrote that, although the four
sides of one part of the octahedron were fairly uniform,
the other part was not in perfect condition, since the
point was broken off and one of the sides was damaged.18
On the damaged side, Korthals (1837) reported, was a
little hole, probably used for fixing the thin gold band
that surrounded the rough diamond.19 An ‘emerald’-
coloured piece of string was attached to the gold band,
which allowed the sultan to wear the diamond as a
necklace. The stone was reportedly found during the
reign of Sultan Adam’s father, Sultan Sulaiman Saidullah
(1761–1825), in the ‘mines’ of Karang-intan (Figures 3
and 4).
20
After Sultan Adam died in November 1857, he was
succeeded by his grandson, Tamdjiddillah al-Watsiq
Billah (1817–1867), the first son of the deceased crown
prince Abdul Rachman (Stutje 2022a, b). His installation marked the beginning of a period of political and
social turmoil that would eventually lead to the Banjarmasin War. In June 1859, Tamdjiddillah resigned under
heavy pressure from the Dutch government, and he
surrendered the regalia of the Sultanate of Banjarmasin,
including the diamond, shortly thereafter. Sometime in
the following year the regalia were transported to the
civil warehouses in Batavia. In July 1861, they were
offered to the Bataviaasch Genootschap (Royal Batavian
Society of Art and Sciences)21, except for the diamond
that would sail to the Netherlands a few months later. 22
Arrival in Europe and Cutting
The first ‘official’ examination of the rough Banjarmasin
took place on board the war steamer Zr. Ms. Ardjoeno,
two days before the ship left the port of Batavia on 16
December 1861. A Muslim diamond expert, Said Adbulla
Alaijderves, determined a weight of 70 ct for the gem
in its setting, which he described as in zilver gevatten
steen of ruwen diamant (‘stone or rough diamond set
in silver’; Figure 6).
23 Apparently nothing was recorded
about the form of the rough. The diamond was then
wrapped in paper and sealed in a yellow palm-wood
14 In Dutch: Zijn geele hoofddoek was op eene zonderlinge wijze gevouwen en had zeker een tiental punten (Korthals 1836, p. 60). 15 Sultan Adam told Korthals that this medal was set with diamonds because it was Soeka Sa(e)kili (he liked it very much; Korthals
1836, p. 61).
16 This cut diamond, which was worn by the son of the sultan (sultan moeda or pangerang Ratoe), is not mentioned in any of the
other nineteenth-century sources (Korthals 1836, p. 61).
17 A year later, Korthals described the diamond as a 72 ct octahedron (Korthals 1837, p. 245).
18 In Dutch: Hij is een vrij regelmatige octaëder, waar van de 4 hoekig goed uitloopen, de andere vierhoek is daarentegen onregelmatiger door het afbreken der punt en eene zijde der 4. kanten, hier is ook een klemgaatje in denzelven, en aan der punten ziet men
een zwart vlekje; de steen is wat de kleur aangaat zuiver. Hij is gevat tusschen een gouden vatsel die de kanten bedekken en hangt
daardoor aan een smarag pennenkoord, hetwelk de plaats van ketting bekleed (Korthals 1836, diary entry 7 August). 19 In Dutch: een tamelijk regelmatige achthoek met een gaatje aan een der kanten (Korthals 1837, p. 245). 20 Korthals wrote that the diamond was a prosakka (pusaka or poesaka) of Sultan Sulaiman. This term refers to specific objects that
have a strong bond with the family ancestors and are considered valuable heirlooms (Korthals 1836, p. 62). The mines of Karangintan are situated on the right side of the map in Figure 4 (see red arrow), between ‘a house of the sultan’ (Huis v.d. Sultan) and
the royal cemeteries (Vorstelijke begraafplaats). 21 See Bestuursvergadering, 13 July 1861 (van der Chijs 1862, pp. 122–125).
22 It was proposed that the Minister of the Colonies should gift the diamond to the Dutch King William III (1817–1890) as an ornament
for his crown (Stutje 2022a, p. 349).
23 NL-HaNA, Colonies, 1850–1900 (2.10.02), inv. no. 1158, 10 March 1862, proceedings of 14 December 1861.
FEATURE ARTICLE
668 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 6: A signed document from 14
December 1861 mentions a weight of 70
ct (top image) and also describes the
Banjarmasin as a ‘stone or rough diamond
set in silver’. The document bears the
names and signatures of the Muslim
diamond expert Said Abdulla Alaijderves,
Captain A. F. Siedenburg and two officials
of the warehouse in Batavia (bottom
image). From NL-HaNA, Colonies, 1850–
1900 (2.10.02), inv. no. 1158, 10 March 1862,
proceedings of 14 December 1861.
box. Upon arrival at the Ministry of Colonies in The
Hague in April 1862, the diamond was unpacked to be
authenticated, after which it remained there for another
two years. In February 1864, Amsterdam diamond broker
Emanuel Vita Israel (1831–1915) examined and weighed
the stone (recording 69⅞ ct) before it was transferred
to De Nederlandsche Bank in Amsterdam.24
It took another five years before a decision was made
to sell the diamond, and in October 1869 the Nederlandsche Handel-Maatschappij (Netherlands Trading Society
or NHM) valued the Banjarmasin at 300,000 guilders
(a devaluation of 100,000 guilders over seven years).
NHM, which specialised in trading colonial products
from the Indies, was asked to suggest the best way to sell
the diamond without disclosing from whom and how
the Ministry of Colonies had acquired it.25 Amsterdam
jewellers Benten & Zonen sent a clear message to NHM:
because of the diamond’s rough form and its imperfect
clarity, they did not expect an offer of more than 100,000
guilders. In fact, they suggested aiming for a sale price of
70,000–80,000 guilders.26 Benten & Zonen was unable to
secure any serious offers in the following months, and
in May 1870, Meijer Moses (Martin) Coster (1818–1880),
director of Coster Diamonds in Paris, France, advised
the ministry to have the diamond cut.
The stone was sent to Abraham Eliazer Daniels (1801–
1880) and his son, Alexander Daniels (1832–1911), managing
directors of Coster Diamonds in Amsterdam (Figure 7).
27 This
company was responsible for the cutting of the Koh-i-Noor
and the Star of the South diamonds in, respectively, 1852
and 1856–1857 (Smith & Bosshart 2002). By August 1870,
the Banjarmasin had been faceted into a modified Old Mine
cut of 37⅜ ct. However, NHM wrote to the ministry that the
diamond did not show a ‘clear brilliance’, as expected, but
instead had a yellowish tint.28 This would have a negative
influence on its value, which NHM lowered to 45,000
guilders.29 With its financial gain diminished, the Banjarmasin diamond was then described as ‘a valuable memorial
of an important event in the history of the Dutch East Indies’
and put back in the safe of NHM.30
24 NL-HaNA, Colonies, 1850–1900 (2.10.02), inv. no. 1441, 22 February 1864, no. 9, minutes of transfer from the Ministry of Colonies
to the Dutch national bank.
25 NL-HaNA, NHM, 2.20.01, inv. no. 428, minutes of the board meeting, no. 72, 8 October 1869.
26 NL-HaNA, NHM, 2.20.01, inv. no. 428, minutes of the board meeting, no. 93, 20 December 1869.
27 NL-HaNA, NHM, 2.20.01, inv. no. 428, minutes of the board meeting, no. 27, 9 May 1870, and NL-HaNA, Colonies, 1850–1900
(2.10.02), inv. no. 6010, minutes of 6 May 1870 E5.
28 In Dutch: een min of meer geelachtigen tint, die van nadeeligen invloed is op de waarde van het juweel. 29 NL-HaNA, Colonies, 1850–1900 (2.10.02), inv. no. 6013, letter from NHM to the Minister of Colonies, 27 August 1870.
30 In Dutch: a kostbaar gedenkteeken van een belangrijke gebeurtenis in de geschiedenis van Nederlands-Indië; NL-HaNA, Colonies,
1850–1900 (2.10.02), inv. no. 2779, minutes of 21 April 1875, no. 19.
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 669
Figure 8: At the 1883 International
Colonial and Export Exhibition in
Amsterdam, the Banjarmasin was
displayed in a pavilion where the
diamond-cutting industry of Amsterdam
was showcased (circled building).
The International Colonial and Export
Exhibition in Amsterdam in 1883,
woodcut by E. & A. Tilly after Johan
Conrad Greive, 1883, Rijksmuseum,
Amsterdam (inv. no. RP-P-OB-89.774).
Figure 7: The Coster diamond factory on the Amstel
River in Amsterdam (depicted here) was where the rough
Banjarmasin diamond was faceted into a modified Old Mine
cut in 1870. Amstel 1-13, watercolour on paper in 1852 by
Cornelis Springer (1817–1891); Amsterdam city archives (inv.
no. 010097015145).
Early Display and Documentation
Although it is often stated that the cut Banjarmasin
diamond was first shown to the public after its transfer
to the Rijksmuseum in 1902, it seems that it was put on
public display almost 20 years earlier. In 1883, Amsterdam
hosted the International Colonial and Export Exhibition
at what is now the Museumplein. In addition to displays
showcasing ‘marvels’ from the Dutch colonies, there
were pavilions to impress the international visitor with
the splendour of Amsterdam’s industries. Its renowned
diamond-cutting industry was showcased in its own
pavilion close to the main building (Figure 8). The
diamond exhibition was extensively covered by Dutch
newspapers after the exhibition’s opening in May 1883.
In one detailed review, specific mention is made of a
‘beautiful brilliant from Borneo weighing 37½ carats’
that was loaned by NHM for the showcase of diamond
broker Emanuel Vita Israel (Anonymous 1883), who
had examined the Banjarmasin almost 20 years earlier
and knew of NHM’s involvement. Because there are
no images of the pavilion’s interior or its showcases,
we do not know the context in which the diamond
was displayed, although it is probably safe to assume
the Sultanate of Banjarmasin was not mentioned as its
previous owner.
The first known photographs of the Banjarmasin
diamond date from 1898 and were included in a Dutch
auction catalogue (Figure 9). The auction was organised
by Emanuel Vita Israel and his brother. The catalogue
lists the Banjarmasin as the first lot and describes it
as Un Brilliant ancient, qualité supérieure, provenant
des mines de Bornéo (Henriques de Castro et al. 1898).
Its weight was listed in both carats (377
/32) and grams
(5.450), and three photographs illustrated different views
of the diamond. In previews of the 23 March event, to
be held at auction house De Brakke Grond, advertisements in Dutch newspapers raised awareness of the
various diamonds, pearls and other pieces of jewellery
that were to be offered. Although most of the announcements were rather general, one from the 23 January
1898 edition of the Algemeen Handelsblad specifically
mentions a ‘Borneo brilliant’ of 39 ct, presumably the
Banjarmasin (Anonymous 1898, p. 12; see Figure 10).
Despite these efforts, the diamond once again failed to
be sold. Emanuel Vita Israel kept the Banjarmasin until
August 1902, when it was transferred as a permanent
loan to the Rijksmuseum, although it was not properly
registered until the year 2000 (Stutje 2022b).
FEATURE ARTICLE
670 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 9: The Banjarmasin diamond is listed as item no. 1 in
three views on this page from the Catalogue d’une très belle
Collection de Diamants, Bruts et Taillés, Perles et Pierres de
Colours… at De Brakke Grond on 23 March 1898 (Henriques de
Castro et al. 1898). The diamond failed to sell at the auction.
Figure 10: A newspaper announcement of the March 1898
auction at De Brakke Grond (see Figure 9) mentions a ‘rare
and clear cut old Borneo brilliant of approximately 39
carats’—presumably the Banjarmasin diamond—being
offered along with other pieces of jewellery. From
Anonymous (1898, p. 12).
METHODS
Analyses of the Banjarmasin diamond took place at both
the Rijksmuseum and the Netherlands Gem Laboratory,
and included standard gemmological testing, ultraviolet-visible-near infared (UV-Vis-NIR), Fourier-transform
infrared (FTIR) and Raman spectroscopy, and DiamondView imaging. The colour was graded using a CIBJO
master stone set of round brilliant-cut diamonds and a
Dialite Pro daylight-equivalent fluorescent lamp (6500
K). Internal features were observed with a standard
gemmological microscope, a Hirox Digital Microscope
KH-7700 and a Nikon Eclipse E600 POL polarising
microscope.
Inclusions were analysed by Raman spectroscopy
using a Thermo DXR Raman microscope with 532
nm laser excitation. Raman spectra were collected
in confocal mode to enable analyses of individual
inclusions on a micron scale (1–2 µm).
Mid-IR spectra were obtained with a Thermo Nicolet
iS50 FTIR spectrometer. UV-Vis-NIR absorption spectra
were collected with a Thermo Scientific Evolution 600
spectrometer in the 280–850 nm range.
Long- and short-wave UV lamps were used in a
darkened room to observe luminescence, and growth
patterns were observed with a DiamondView fluorescence imaging instrument, which uses ultra-short-wave
UV radiation (<230 nm).
RESULTS
The properties of the Banjarmasin diamond are
summarised in Table I. It weighs 38.23 ct and is faceted
as a modified Old Mine cut, with ten bezel facets on
the crown and ten pavilion facets (Figures 1 and 11),
instead of the usual eight bezel and eight pavilion
facets. (On the long sides of the diamond there was
enough space to add extra facets to improve its sparkle
and brilliance.) Apart from the typically high overall
depth and large culet, the stone has a fairly large table
as compared to the usually small table of an Old Mine
cut. The outline of the diamond is sharp with a thin,
faceted girdle. Three naturals are present: one on
the girdle (Figure 12) and two on the edges of two
bezel facets.
Weight 38.23 ct
Measurements 21.86 × 17.37 × 13.86 mm
Colour E (exceptional white)
Clarity SI2
Cut Modified Old Mine cut
Depth 79.8%
Table 59%
Symmetry Good
Polish Good
Girdle Faceted, where present
UV fluorescence Very weak blue (long-wave) or
inert (short-wave)
Phosphorescence None
Diamond type IaAB
Table I: Properties of the Banjarmasin diamond.
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 671
Crystal
Needle
Feather
Chip
Natural
Figure 11: A schematic drawing of the
Banjarmasin diamond (modified Old
Mine cut) shows ten bezel facets on the
crown and ten pavilion facets on the
pavilion. A plot of major internal (red)
and external (green) features illustrates
why it received a clarity grade of SI2.
800 µm
Figure 12: One of the naturals on the Banjarmasin diamond
is located along a thin, faceted portion of the girdle. In
many places, the girdle is absent and the crown-pavilion
junction is razor sharp (see right-hand side of this image).
Photomicrograph by J. C. Zwaan.
800 µm
Figure 13: Many black needle-like inclusions are present in
the Banjarmasin diamond, and they are commonly oriented in
specific (mainly octahedral) directions. Photomicrograph by
J. C. Zwaan.
The E colour grade (also known as ‘exceptional
white’) was determined by viewing the diamond table
down, through the pavilion, at different angles, but
especially with its long and short axes at about 45° to
the observer. The stone was oriented in this way so that
its outline most closely resembled that of the round-brilliant master stones and showed the best visual ‘average’
for the amount of colour observed (cf. King et al. 2008).
Numerous dark inclusions were easily visible to the
unaided eye. A schematic plot of the most prominent
inclusions reflects their relative size and position (again,
see Figure 11). Comparing the sizes of the inclusions
and their reflections to the size of this diamond, and
relating these characteristics back to a smaller, more
average-sized diamond (e.g. 1 ct), we assigned a clarity
grade of SI2.
Many of the dark inclusions were needle-like and
oriented in specific directions (Figure 13), which appear
to be largely controlled by the octahedral growth of the
host diamond. Also observed were transparent colourless inclusions associated with stress haloes that were
filled with a black material (Figure 14). The colourless
inclusions were identified as forsterite (olivine) by
Raman micro-spectroscopy. Because the Raman signal
of the host diamond was very strong, the spectral
features of these inclusions were barely visible. But
by scanning specifically in the 1000–600 cm–1 range,
the characteristic spectral features of forsterite became
apparent (Figure 15). The black inclusions could not
be identified by Raman micro-spectroscopy.
FTIR spectroscopy yielded features consistent with
those of type IaAB diamond (Figure 16). Strong absorption in the 1300–1100 cm–1 region indicated the presence
of both A centres (a pair of nitrogen atoms substituting
for carbon atoms, producing a peak at 1282 cm–1) and B
centres (a carbon vacancy surrounded by four nitrogen
atoms, substituting for carbon atoms, causing a peak at
1175 cm–1). A strong platelet peak (caused by extended
planar defects in {100} lattice planes, consisting of arrays
of carbon interstitials) was present at 1367 cm–1, and a
minor peak at 3107 cm–1 was related to the presence of
hydrogen (cf. Collins 1982, 2001, 2003; Goss et al. 2003).
The spectrum also contained a small feature at 1522
FEATURE ARTICLE
672 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 14: Colourless, transparent olivine inclusions in the Banjarmasin diamond display surrounding stress haloes filled with a
black material. Photomicrographs by J. C. Zwaan; image widths (a) 3.7 mm and (b) 6.6 mm.
a b
cm–1, which is occasionally detected in natural untreated
diamonds (e.g. Dobrinets et al. 2013).
UV-Vis-NIR spectroscopy showed an absorption edge
at 325 nm and a peak at 415 nm due to N3 centres (three
nitrogen atoms surrounding a vacancy; cf. Collins 1982;
Figure 17). The 415 nm peak and the related absorption
near 380 nm only attained approximately 0.9 absorbance unit, which is very weak, and with no typical cape
absorption at 478 nm, virtually no yellow colouration
was present (i.e. E colour grade). So, like most gem
diamonds (cf. Anderson & Payne 1998), the Banjarmasin contains a mixture of A and B centres, together
with a low amount of N3 centres that is just a fraction
of the concentrations of A and B centres.
Fluorescence to long-wave UV radiation was very
Figure 15: The
strong Raman
signal of the host
diamond at 1332 cm–1
makes the features
of an analysed
inclusion difficult
to detect (blue
trace). Scanning
the specific region
between 1000 and
600 cm–1 makes the
forsterite spectrum
more apparent (red
trace).
Raman Shift (cm-1)
1800 1600 1400 1200 1000 800 600 400 200
Intensity
Raman Spectra
Diamond
1332 855
823
Forsterite inclusion
weak blue, and the stone was inert to short-wave UV. The
long-wave UV fluorescence appeared patchy when viewed
from the pavilion (Figure 18). DiamondView imaging
clearly revealed the diamond’s growth patterns (Figure 19),
with blue luminescence. A complicated growth structure
was visible in the core, surrounded by regular octahedral
growth zones. The core area generally fluoresced only
slightly stronger blue. The contact between the core area
and the outer zone appeared jagged due to resorption
after an early growth phase (cf. Wiggers de Vries 2013).
Small displacement zones or slip lines (at left in Figure
19) indicate plastic deformation during an episode of later
octahedral growth. Viewed from the pavilion side, mainly
octahedral growth zones could be observed, with the same
core structure near the culet as seen from the table side.
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 673
Wavelength (nm)
200 300 400 500 600 700 800 900
Absorbance
UV-Vis-NIR Spectrum
415
DISCUSSION
Black inclusions are poor Raman scatterers, so the ones
in this diamond could not be identified with certainty.
Such black inclusions commonly consist of sulphides
(pyrrhotite or pentlandite) and graphite, although highly
reflective chromite has also been identified (e.g. Harris
1972; Harris et al. 1972; Koivula 2000). The needle-like
black inclusions (Figure 13) look very similar to patterns
of small black platelets and needles that form distinct
clusters or directional arrays along diamond cleavage
planes, and have previously been identified as graphite
(Harris 1972). The black material in the fractures around
the forsterite inclusions may consist of graphite or
sulphides. This material is hosted by tension fractures
that are caused by the greater volumetric expansion
of olivine than diamond during a decrease in pressure
that took place after the diamond’s formation (Harris
et al. 1972).
As mentioned in the History section of this article,
the Banjarmasin diamond reportedly originated from
southern Kalimantan on the island of Borneo, one
of the oldest-mined sources of diamonds. However,
most diamonds from Kalimantan are relatively small
(averaging about 0.30 ct; Spencer et al. 1988), which
could raise the question of whether the Banjarmasin
originated elsewhere. For instance, India has historically
been known as an important source of large ‘white’ and
pink ‘Golconda’ diamonds (e.g. Bari & Sautter 2001, pp.
96–101). However, large Golconda diamonds have often
Figure 16: The FTIR
spectrum of the
type Ia Banjarmasin
diamond supports
the presence of a
mixture of A and
B centres in the
1300–1100 cm–1
region, along with a
strong platelet peak
at 1367 cm–1.
Wavenumber (cm-1)
6000 5000 4000 3000 2000 1000
Absorbance
FTIR Spectrum
3107
1367
1522
Figure 17: The
UV-Vis-NIR
spectrum of the
Banjarmasin
diamond shows
only a weak N3
paramagnetic
absorption (with a
415 nm zero-phonon
line), corresponding
to its virtual lack of
colour.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
FEATURE ARTICLE
674 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 19: A DiamondView fluorescence image of the Banjarmasin diamond reveals a combination of complicated early growth
patterns and later regular octahedral growth. Photo by J. C. Zwaan; image width 15.9 mm.
been characterised as the rare type IIa, which does not
contain nitrogen (e.g. King et al. 2008), so India seems a
less likely source for the Banjarmasin. Also, there is some
evidence of large diamonds coming from Kalimantan. In
1789, the 367 ct Matan diamond was reportedly found
in the Landak River of western Kalimantan (Ball 1931),
and several diamonds exceeding 100 ct once belonged
to the Malay Prince of Landak (Bauer 1904). A more
recent find from Kalimantan, in 1965, of the 166.85 ct
Tri Sakti diamond (subsequently faceted into a 50.53 ct
emerald cut; Spencer et al. 1988) also confirms that large
diamonds have been found in this region.
Since diamonds are formed in the earth’s mantle,
their properties cannot be used to provide convincing
evidence for a specific geographic origin (cf. Smith
et al. 2022). The Banjarmasin diamond has characteristics that are commonly seen in many diamonds
from all over the world, consistent with those of
other diamonds from Kalimantan. Most Kalimantan
diamonds are of good gem quality, are generally
colourless or pale brown (less commonly pale
yellow), typically have simple octahedral zonation
and may show plastic deformation (with rare cases
of more complex internal structures and episodes
Figure 18: (a) The 38.23 ct
Banjarmasin diamond
fluoresces very weak blue to
long-wave UV radiation. (b)
The blue luminescence appears
patchy when viewed on the
pavilion side of the stone.
Photos by J. C. Zwaan.
a b
BANJARMASIN DIAMOND
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 675
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of resorption). Many are well-aggregated type IaAB
(implying a long-term mantle residence time and/or
high temperatures of formation), contain detectable
hydrogen impurities, and have inclusion parageneses that are 68% peridotitic (containing forsterite;
Smith et al. 2009). The Banjarmasin diamond shows
consistent features: it is colourless, shows octahedral
growth zoning and displacement zones indicating
plastic deformation, and contains forsterite inclusions.
Strong absorption in the 1300–1100 cm–1 indicates the
presence of aggregated nitrogen in A and B forms.
Other indicators that both A and B aggregates are
present in comparatively large concentrations are the
very weak fluorescence, indicating the presence of A
aggregates quenching the fluorescence caused by N3
centres (cf. Collins 1982), and the strong platelet peak,
which has an intensity proportional to the absorption
produced by the B aggregates (Collins 2001; Smith et
al. 2009).
CONCLUSION
The Banjarmasin diamond in the collection of the
Rijksmuseum in Amsterdam reportedly originated
from southern Borneo (in today’s South Kalimantan,
Indonesia), and was confiscated by the Dutch from the
Sultanate of Banjarmasin. It therefore is a symbol of
the controversial history of Dutch colonial rule in this
part of Indonesia. As a rough diamond weighing 70+
ct, it arrived in the Netherlands in 1862. In 1870, it was
faceted into a modified Old Mine cut weighing 38.23 ct.
Over the next three decades, there were several unsuccessful efforts to sell it. Ultimately, the diamond was
transferred to the Rijksmuseum in 1902. During recent
examinations of the diamond as reported in this article,
it was graded as E colour and SI2 clarity. It is a type
IaAB diamond, contains forsterite and probable graphite
inclusions, and is one of the few historical examples of
large diamonds found in southern Borneo.
FEATURE ARTICLE
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The Authors
Suzanne van Leeuwen fga
Rijksmuseum, Postbus 74888, 1070 DN
Amsterdam, The Netherlands
Email: [email protected]
Dr J. C. (Hanco) Zwaan fga
Netherlands Gem Laboratory – Naturalis
Biodiversity Center, Postbus 9517, 2300 RA Leiden,
The Netherlands
Acknowledgements
We thank Dirk van der Marel for assistance in
drawing the modified Old Mine diagram and
stitching separate DiamondView images into one
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historian Dr Klaas Stutje, and jewellery historians
René Brus and the late Erik Schoonhoven, for
sharing and discussing valuable source material
on the Banjarmasin diamond. Collections archivist
Karien Lahaise of Naturalis kindly shared scans of
the unpublished diaries of P. W. Korthals.
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html?id=JRQ5AQAAIAAJ.
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678 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
Clues to Understanding
the Enigma of the Unusual
Asterism in ‘Mercedes-Star’
Quartz
Jean-Pierre Gauthier, Emmanuel Fritsch, Thanh Nhan Bui
and Jacques Fereire
ABSTRACT: ‘Mercedes-star’ quartz contains abundant long, narrow, randomly oriented rutile inclusions, and is notable for its unusual asterism. In particular, it displays weak three-rayed stars, with rays
that meet at the centre as in the Mercedes-Benz emblem. In the classical theory of asterism such stars
cannot exist, and they have not been seen in any other gem materials. We examined three samples
(two spheres and one egg shaped) of ‘Mercedes-star’ quartz from Brazil. Ideally, this material displays
six three-rayed stars located along two latitude planes parallel to the equatorial plane (perpendicular
to the c-axis). In addition, six faint four-rayed stars are located along the equatorial plane. Therefore,
in total, this quartz may display 18 stars located on three coaxial circles. The rays of all the stars
consist of a path of reflective segments of unknown illumination origin, but which appear to result
from double reflection of the light beam, first by Brazil-law twin planes and then by the rutile needles,
making the phenomenon uncommon. In addition to the abovementioned stars seen in reflected light
(epiasterism), more-transparent ‘Mercedes-star’ quartz may also show two six-rayed stars with transmitted light (diasterism) when illuminated from behind and viewed parallel to the c-axis.
The Journal of Gemmology, 38(7), 2023, pp. 678–695, https://doi.org/10.15506/JoG.2023.38.7.678
© 2023 Gem-A (The Gemmological Association of Great Britain)
Quartz is one of the most abundant minerals
on Earth. It occurs in many varieties, not
just colour-wise (e.g. amethyst, citrine,
prasiolite, pink quartz and smoky quartz)
but also inclusion-wise (Hyršl & Niedermayr 2003). Of
all quartz inclusions, rutile is relatively common, and
it occurs in some spectacular varieties (e.g. Gübelin &
Koivula 2005, pp. 627–631). Many of these are artistically highlighted by lapidaries.
Several types of inclusions are responsible for various
optical phenomena in gems, such as aventurescence,
iridescence, chatoyancy and asterism. Chatoyancy in
quartz is produced by a network of parallel acicular
inclusions oriented along a particular crystallographic
direction of the quartz host (see, e.g., Kane 1985; Koivula
1987; Choudhary & Vyas 2009). Relatively parallel
coarse rutile needles sometimes produce pseudo-cat’seyes (Johnson & McClure 1997). Asterism in quartz is
typically caused by several networks of acicular inclusions lying in the basal plane that produce six-rayed stars
and, less frequently, 12-rayed stars (Johnson & Koivula
1999). Additional inclusion networks outside the basal
plane result in multi-asterism, mainly consisting of fourand six-rayed stars (Schmetzer & Glas 2003).
Here we examine so-called Mercedes-star rutilated
quartz (e.g. Figure 1), which displays three-rayed
asterism with branches that meet at the centre of the star
(like the emblem of the famous German car manufacturer), and exhibits features that are contrary to the most
commonly accepted theory of asterism (cf. Gübelin et
al. 1982; Weibel 1982). This kind of asteriated quartz
was briefly described by Gübelin and Koivula (2005,
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 679
ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
Figure 2: A smaller Mercedes-star quartz sphere measuring
28 mm in diameter (150 ct) was also examined for this study.
It is shown here in transmitted light to highlight the interesting
form of its inclusions. Photo by J.-P. Gauthier.
Figure 1: These
two samples of
Mercedes-star
quartz were
examined for
this study: (a)
a large sphere
(1,470 ct; 60 mm
in diameter) and
(b) an egg-shaped
specimen (252.5
ct; 41 mm long ×
30 mm diameter).
Collection of E.
Fritsch; photos
by J.-P. Gauthier.
a b
pp. 548, 822) and later encountered by Hainschwang
(2007) in five samples from Brazil. More recently, it was
reported by Steinbach (2017), as well as by Schmetzer
and Steinbach (2022, 2023), in rutilated quartz also
from Brazil (apparently similar to the samples described
here). The arrangement of the stars located at various
positions relative to the optic axis of the host quartz
is documented in the present article using polished
specimens of rutilated quartz from Brazil, one of
which was sacrificed to study the cause of the threerayed asterism. We report a number of observations
not previously described for Mercedes-star quartz, and
also propose some ideas to explain the formation of its
unique asterism.
MATERIALS AND METHODS
The three Mercedes-star quartz samples examined for
this study all came from Bahia State, Brazil. The first
was an opaque sphere of 60 mm diameter (1,470 ct;
Figure 1a). This sample was used for most of the observations, because the stars were easiest to see and all 18
(12 three-rayed and six four-rayed) stars were visible.
The second was an egg-shaped specimen measuring
41 mm long and 30 mm diameter (252.5 ct; Figure
1b), which was semi-transparent in transmitted light,
making it ideal for observing any diasterism. The
third sample was a 28-mm-diameter sphere that was
somewhat translucent, due in particular to its smaller
size (150 ct; Figure 2). This last sample was sliced
to prepare petrographic thin sections for observation
between crossed polarisers.
To describe the asterism in our samples, it was
necessary to develop a protocol to locate the centres of
all the stars. The following procedure was used on the
large sphere (Figure 1a). First, the light source (such as
the sun) and the observer faced the same direction. In
this orientation, the specular reflection (the image of the
light source reflected by the surface of the sphere as seen
by the observer) was approximately in the centre of the
spherical surface (Figure 3a). Then, the centre of a star
was moved (by rotating the sphere) to coincide with this
specular reflection (Figure 3b), and a small disc of paper
was affixed to indicate this position (Figure 3c). This was
done for the centre of each star. For the purpose of this
study, these positions of the star centres are called star
spots. They should not be confused with light spots, as
previously described for star rose quartz spheres (e.g.
Schmetzer & Krzemnicki 2006; Killingback 2008).
The relative angular positions of the star spots on the
680 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
a b c
Figure 3: The positions of ‘star spots’ on the large quartz sphere were determined using the following procedure: (a) First the
light source and the eye of the observer are aligned with the sphere’s centre, so the specular spot becomes centred on the
sphere. (b) Then the sphere is rotated slightly to bring the centre of a star in coincidence with the specular spot. (c) The position
of the star spot is marked with a disc of sticky paper. Angle values between branches are about 130° (green arrow) and 115°
(yellow arrows). Photos by J.-P. Gauthier.
large sphere were then recorded with a Tri-Mesures MC
1004E three-dimensional coordinate measuring machine
(manufactured by MétroVali, Villedieu-sur-Indre,
France) equipped with Wenzel WM/Quartis metrological software. Experimentally, five non-coplanar points
on the sphere first defined the sphere’s centre (denoted
Ω). The coordinates of each star spot were obtained in
relation to this origin. The next step was to calculate the
coordinates of the north pole (P) and south pole (P’)
of an axis passing through the diameter of the sphere,
making it possible to evaluate the angular positions of
the spots. (Note: Due to the positional symmetry of the
spots as described below, the quartz c-axis was determined and chosen as the reference axis P–P’.) We could
then calculate the angular positions (with respect to the
c-axis and/or the equatorial plane) of the radii joining
the sphere centre Ω to the different star spots. Due to
uncertainty in positioning the star spots (discussed
further below), the angular values were rounded to the
nearest half degree.
To identify the acicular inclusions in the quartz,
we used a Jobin Yvon T64000 high-resolution Raman
spectrometer coupled with an Olympus binocular
microscope (up to 100×magnification). With 514 nm
excitation from an Ar+ laser, we employed a triple-subtractive configuration to eliminate the effect of the
excitation line, along with a diffraction grating (600
lines/mm), confocal mode and a resolution of approximately 4 cm–1.
RESULTS
Macroscopic Observations
General Features of the Asterism. Viewed in reflected
light, 18 star spots were identified on the large quartz
sphere, which were distributed on three coaxial circles
(Figures 4 and 5a). A set of six four-rayed star spots
lay along the median (‘equatorial’) plane, and two
symmetric sets of three-rayed star spots were located
along parallel (‘latitude’) planes on either side of this
equatorial plane. This arrangement strongly suggests
that the normal to all of these circles is the quartz c-axis
(optic axis), which is vertical in Figures 4a and 5, and
perpendicular to the plane of the photo in Figure 4b.
Figure 4: (a) When the large quartz sphere is
positioned with the quartz three-fold c-axis lying
in the plane of the figure, there are six threerayed stars in the upper and lower hemispheres
(green arrows) and six four-rayed stars along the
equatorial plane (red arrow). These three sets lie
on three parallel circles coaxial with the quartz
c-axis. (b) A view along the quartz three-fold axis
(c-axis) shows the arrangement of the six star
spots of the three-rayed stars (green arrows).
The star spots of the six equatorial four-rayed
stars (barely visible around the perimeter of the
sphere) are indicated by red arrows. Photos by
J.-P. Gauthier.
a b c-axis
c-axis
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 681
ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
a b
Meridian
(longitudinal arc)
AnΩP
49.5°– 50.5°
Latitude An
39.5°– 40.5°
Latitude Bn
34°– 42.5°
c-axis
Parallel
(latitude plane)
Parallel
(latitude plane)
Equatorial
plane
MnΩMn+1
52.5°– 65°
BnΩP’
47.5°– 56°
Figure 5: (a) The locations of the 18 star spots seen on the large quartz sphere are shown on this diagram. The labels P and P’
show the positions of the north and south ‘poles’ of the c-axis, respectively. (b) A corresponding diagram is labelled with the
nomenclature of the star spots relative to their angular positions on meridians (longitudinal arcs connecting the poles) and
parallels (or latitude planes) of the quartz sphere. The labels An and Bn correspond to three-rayed stars, while Mn refers to the
four-rayed stars along the equatorial plane.
This could not be verified directly on the large sphere,
which was much too thick to be transparent between
crossed polarisers, but it was later confirmed using the
small sphere (see below).
The appearance of the three-rayed stars in Mercedesstar quartz stands out when compared with typical
asterism because of two main characteristics. (1) As
seen in Figures 1 and 3, each ray of the star seems to
be made of a multitude of reflective points or segments.
The branches are relatively wide and diffuse—appearing
as shiny, intermittent lines made up of reflections from
rutile needles—rather than continuous, sharp and linear
rays as in star corundum, for example. (2) The branches
of the three-rayed stars meet at a central point, rather
than crossing each other to form a classic six-rayed star.
However, as for every asteriated stone, the stars move
when one of the three entities—stone, light source or
observer—shifts while the other two are fixed. Rotating
the stone causes the branches of the star to move in the
same direction. However, if the lamp or the observer
moves, the star shifts in the opposite direction (cf.
Gübelin et al. 1982). In addition, the arms of the stars
are linked together in a network (Schmetzer & Steinbach
2023) that moves as the stone rotates relative to the
light source, as in typical asterism exhibited by a multistar network, such as seen in garnet (Walcott 1937;
Schmetzer & Bernhardt 2002) or quartz (Schmetzer &
Glas 2003).
Position and Shape of the Stars. The 18 star spots
are distributed as follows: six of them are located
on each of three parallel circles centred on the same
axis, and three of them are on each of six meridians
positioned at about 60° of longitude from each other
(Figure 5a). Each meridian contains two three-rayed
stars opposite in latitude on either side of an equatorial four-rayed star.
Each equatorial four-rayed star has a weak vertical
branch (following a meridian) and a much weaker
horizontal branch (Figure 6). The lack of visibility
of the latter branch is likely the reason why these
four-rayed stars were not mentioned in previous publications about Mercedes-star quartz (Steinbach 2017;
Schmetzer & Steinbach 2022) until recently (Schmetzer
& Steinbach 2023).
The three-rayed stars have one branch along a
meridian (joining the vertical branch of a nearby
four-rayed star). The other two branches make an
angle of about 115° with the meridian branch and an
angle of 130° to one another (Figure 3c). This means
that the cause of the meridian branch differs from that
of the other two. Of course, there is no need for the
Mercedes-star branches to be evenly spaced at 120°,
since in quartz there is no three-fold axis of rotation
other than the one connecting the two poles (i.e. the
c-axis, as typical hydrothermal α-quartz is trigonal).
The presence of six stars on each of the parallel circles
682 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
Figure 6: The four-rayed asterism on the large quartz sphere
is difficult to capture in a photograph. The vertical ray is
somewhat visible here, but only part of the horizontal ray
is relatively easy to see (yellow arrow). Compare this to the
sample in the centre of figure 19 in Hainschwang (2007).
Photo by J.-P. Gauthier.
gives a pseudo-hexagonal distribution, reflecting the
pseudo-hexagonal symmetry of quartz. This suggests
that: (1) the quartz z faces are as prominent as the r
faces, or (2) twinning has occurred with parallel axes
of two trigonal domains inducing the six-fold axis
(Frondel 1962).
Table I lists the positional data for the 18 star spots
recorded for the large sphere using the three-dimensional coordinate measuring machine. (To identify
each star spot, the nomenclature shown in Figure 5b
was adopted). The latitude values of the six threerayed star spots in the ‘northern hemisphere’ were
very similar, with values of 40°±0.5°. Those of the
southern hemisphere, which would be expected to have
symmetrical latitude values, showed greater variation
(34°–42.5°). There was also some variation from the
expected latitude of 0° for the four-rayed stars along the
equatorial plane (0.5°–4.5°). In longitude, the angular
spacing between consecutive four-rayed star spots
should approach a theoretical value of 60°, but some
measurements were quite far away from it, ranging from
52.5° to 65° (again, see Table I).
The deviations from the expected values are
probably due to the uncertainty of marking the star
spots on the surface of the sphere (estimated at 2–3
mm), and not from the measuring machine (with an
uncertainty of about 10 µm). The marked positions of
the star spots were imprecise for two reasons. First,
the observer’s head obscures the sphere unless it is
slightly away from the theoretical line defined by the
illumination source (e.g. the sun) and the observer in
order to see the specular reflection. A similar situation
exists if the light source is a lamp placed directly in
line between the observer’s eye and the sample: the
Angles AnΩP
A1ΩP A2ΩP A3ΩP A4ΩP A5ΩP A6ΩP
50 50 49.5 50 50.5 49.5
Latitude of An 40 40 40.5 40 39.5 40.5
Angles BnΩP’
B1ΩP’ B2ΩP’ B3ΩP’ B4ΩP’ B5ΩP’ B6ΩP’
51 49 47.5 56 54 53
Latitude of Bn 39 41 42.5 34 36 37
Angles MnΩP
M1ΩP M2ΩP M3ΩP M4ΩP M5ΩP M6ΩP
89.5 89 88.5 88 85.5 86.5
Latitude of Mn 0.5 1 1.5 2 4.5 3.5
Angles MnΩMn+1
M1ΩM2 M2ΩM3 M3ΩM4 M4ΩM5 M5ΩM6 M6ΩM1
56.5 65 52.5 60 62 62
* The darker tinted boxes indicate data that deviate most significantly from their expected values.
Table I: Latitude and longitudinal angle values (in degrees) for all 18 star spots on the large Mercedes-star quartz sphere.*
observer will be unable to see the specular reflection
unless the sphere is moved slightly to one side of the
lamp. Second, the star branches are wide and consist
of intermittent lines, so the star spots themselves are
not well defined. Due to the resulting inaccuracy in
the positions of the spots, the angular deviation ∆θ
with respect to an ideal position can reach up to ∆θ =
(∆d/R)×(180/π) degrees, or about 6° for ∆d = 3 mm
(linear deviation at the surface of the sphere of radius
R) and R = 30 mm (as for the large sphere) with the
constant π = 3.1416.
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ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
Movement of the Stars with Rotation of the Sphere.
The sketch in Figure 7 shows how the stars move upon
rotation of the sphere in various directions. In all cases in
Figure 7, the light source and the observer are perpendicular to the drawing plane. On each circle representing a
projection of the sphere, black points show the positions
of the star spots, and various manifestations of the threeand four-rayed stars are shown as shaded bands. Two
directions of rotation are shown in a series of five steps:
1. In Figure 7a, the sphere is rotated around a horizontal
axis, starting with the c-axis perpendicular to the plane
of the drawing (parallel to the direction of the light
source and the observer). Initially, the set of six star
spots forms a virtual hexagon, with no visible optical
effect. They move towards the top of the sample as the
rotation progresses, and a three-rayed star appears at the
bottom after about 30° of rotation. At 50°, the centre
of this star is positioned at the centre of the sphere.
Further rotation of about 70° causes it to disappear at the
top of the specimen, giving way to a cat’s-eye-like line
occupying the entire height of the sphere. A four-rayed
star then appears at the bottom, whose centre eventually
occupies the centre of the sphere after a 90° rotation.
2. In Figure 7b, the sphere is rotated counter-clockwise around the vertical c-axis, starting from the last
position in Figure 7a. The four-rayed star moves away
to the right and then disappears, and then another
four-rayed star appears from the left.
Additional Stars Visible with Transmitted Light
(Diasterism). The distribution of the three-rayed
star spots on the egg-shaped sample indicated that
its P–P’ axis is the quartz c-axis. Two unexpected
(and not previously described) six-rayed stars were
observed at each pole of the egg when this somewhat
transparent specimen was illuminated from behind
with a standard white-light torch parallel to the c-axis
(Figure 8). To see the six-rayed diasterism, the lamp
had to be held a few tens of centimetres from the
opposite end of the egg. Bringing the lamp closer to
the egg caused the star to disappear. Using the same
light source, we did not observe any such six-rayed
stars on the sample by reflection at either the top or
the base of the egg.
Precessional movement of the lamp around the
axis induced movement of the star that was exactly
as observed for a rose quartz sphere that displayed
Figure 7: Sketches of the different aspects of the asterism on the large Mercedes-star quartz sphere are shown with the source
and observer fixed in the same direction perpendicular to the drawing plane. The black points represent the star spots and the
shaded bands correspond to the branches of the stars. (a) At 0° (far left), the sphere is positioned with the c-axis (red circle) of
the quartz crystal perpendicular to the drawing plane. Rotation is then carried out around a horizontal axis with angular values of
30°, 50°, 70° and 90° (from left to right). A three-rayed star, absent at 0°, appears near the bottom of the sphere at about 30°,
reaches specular reflection at 50° and then disappears near 70°, where a four-rayed star begins to rise up to, at 90°, the centre
of the hemisphere. (b) Starting from the last position above, rotation around the vertical three-fold axis (c-axis) at angular values
of 15°, 30°, 45° and 60° (from left to right) shows the movement of a four-rayed star. Star spots marked with the letters M, R and
Z are located on the poles m, r and z of a quartz crystal, as indicated later in the Discussion section.
a
b
c-axis
c-axis
c-axis
684 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
Figure 8: A six-rayed star appears when the semi-transparent
egg-shaped quartz is illuminated from behind (diasterism),
with the light direction parallel to the c-axis (perpendicular
to the plane of the image, which is also the symmetry axis of
the egg). The black points mark the positions of three-rayed
star spots. The diameter of the egg’s cross-section is 30 mm.
Photo by T. N. Bui.
similar diasterism (Killingback 2006). When the lamp
was moved to the right of the axis, the star moved to the
left. However, the star disappeared with further angular
deviation of the lamp from the c-axis.
When the six-rayed star was centred on the c-axis, its
branches lay along the same meridians as the Mercedesstar spots (again, see Figure 8). The six-rayed diasterism
is also apparently created by illumination of rutile
needles, as for the three- and four-rayed stars. However,
the exact cause of the six-rayed diasterism needs further
investigation.
Microscopic Observations
Inclusions. All three quartz samples contained
abundant more- or less-curved needles, which we
assumed to be typical rutile inclusions. This was
confirmed by Raman spectroscopy.
The large sphere shown in Figure 1a appears dark
brown, probably due to the large amount of brown
rutile inclusions present. The egg-shaped sample
is lighter in colour and looks somewhat reddish.
Although the host quartz is transparent, the density
of the rutile inclusions restricts visibility through the
interiors of the stones. The rutile needles have many
different aspects, but most are gently curved and look
like ‘Venus hairs’ (i.e. fine golden to reddish curved
needles), scattered randomly in the quartz matrix
(Figure 9a). Some straighter ones sometimes cross
at a node (Figure 9b). Others are roughly aligned in
‘combs’ that form two perpendicular planes joining
along a coarser crystal, as in ‘platinum quartz’
(Koivula & Tannous 2003; Figure 9c), consistent with
the tetragonal nature of the central rutile crystal. Interestingly, healed fractures sometimes transect many
rutile needles or ‘hairs’ (Figure 9d). Rutile inclusions
can also be accompanied by two-phase fluid inclusions
decorating healed fractures (Figure 9e). Because of the
random orientation of the rutile needles, one might
assume a priori that, despite their abundance, they
have little to do with the asterism. Nevertheless, due
to their high density, the possibility that they could
play a role should not be overlooked.
Water-Drop Test. The water-drop test is typically
performed on flat or even unpolished surfaces to detect
chatoyancy or asterism (Gauthier 2011). The test consists
of applying a small drop of water on the surface of the
stone using a syringe fitted with a hypodermic needle.
Observing the sample through the curved surface of the
water drop allows one to check for an optical effect due
to a possible network of very fine, oriented inclusions,
invisible under an optical microscope, which could
justify classical asterism.
We repeated this experiment on several parts of the
large sphere, including on arms and nodes of the stars,
and at the ends of the c-axis. All of the tests proved
negative, ruling out the possibility of a classical scattering
phenomenon due to sets of tiny parallel needles.
Reflections from the Rutile Needles. As mentioned
above, the branches of the stars do not appear continuous, as for normally chatoyant and asteriated stones.
Instead, they consist of concentrations of illuminated
segments of randomly oriented acicular rutile inclusions, giving the appearance of the bright reflective
dots or lines mentioned above and seen in Figure 10a.
The bright lines seem to be due to reflections from
the needles’ surfaces. The needles act like a multitude
of mirrors giving the shiny aspect to the branches of
the stars. The needles are not illuminated along their
entire length, for at least two reasons: (1) even if the
incident rays come from a parallel beam of light, the rays
refracted in different points of the sphere are no longer
parallel and arrive in different orientations on a rutile
needle, and (2) many of the rutile needles are curved.
The cross-sections of the individual needles are
significantly smaller than those found in typical coarse
rutilated cat’s-eye quartz (Johnson & McClure 1997;
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ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
Figure 9: Rutile needles in Mercedesstar quartz can (a) be randomly
distributed; (b) cross at a node; (c)
have comb-like structures arranged in
two perpendicular planes anchored
on a larger straight crystal; (d)
transect a healed fracture; or (e)
be accompanied by two-phase
fluid inclusions (negative crystals)
decorating a healed fracture. All
images are from the large sphere.
Photomicrographs by J.-P. Gauthier;
fields of view (a) 3 × 3 mm, (b) 1 × 1 mm,
(c and d) 12 × 12 mm and (e) 3 × 3 mm.
Figure 10: (a) Rutile needles in
the large quartz sphere are mainly
illuminated in a direction that is
roughly parallel to the star branch
(here, in a horizontal direction). The
orientations of the reflections are
best observed by slightly squinting
when looking at the picture. (b)
At high magnification, the shiny
reflective segments of the rutile
needles show a striated appearance.
Photomicrographs by J.-P. Gauthier;
fields of view (a) 10 × 10 mm and
(b) 1 × 1 mm.
a b c
d
a
e
b
Koivula & Tannous 2004). In our samples, the width
of these rutile needles, measured on enlarged photomicrographs taken with a binocular microscope at
80× magnification, is about 50 µm and never exceeds
100 µm. The reflections from the needles are actually
composed of very thin luminous striae, as seen only at
high magnification (Figure 10b).
Brewster Fringes in the Quartz. The smaller Mercedesstar quartz sphere was sliced parallel to two planes at
90°: (1) along the equatorial plane perpendicular to the
c-axis and (2) parallel to the c-axis. When the curved
surface of a resulting quarter-sphere sample (Figure 11a)
was illuminated from above parallel to the c-axis, we
observed iridescent colours (Figure 11b).
With transmitted lighting and crossed polarisers, we
observed rectangular or parallelogram-shaped domains
underlined by interference colours at different levels
within the sample (Figure 11c, d). These features correspond to Brewster fringes, and are due to alternating twin
lamellae seen between crossed polarisers, as reported
in amethyst (see, e.g., Lu & Sunagawa 1990; Notari et
al. 2001; Schmetzer 2017). However, they do not have
the same sectorial appearance as seen in amethyst.
686 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
a
b
c d
Figure 11: (a) A quarter-slice from the small quartz sphere (2.8 mm diameter),
bounded by two planes at 90°, is shown from above, lying on its equatorial plane
with the c-axis perpendicular to the plane of the picture. (b) In reflected lighting,
it shows iridescent colours. Between crossed polarisers, with illumination from
the rear and higher magnification, two distinct sets of Brewster fringes appear
with (c) rectangular and (d) parallelogram shapes. Photos by J.-P. Gauthier;
fields of view (b) 10 × 10 mm, (c) 3.5 × 3.5 mm and (d) 4 × 4 mm.
c-axis
Nevertheless, they reveal the presence of superimposed
domains of left-handed and right-handed quartz, corresponding to Brazil-law twinning.
Crystallographically Oriented Thin Sections. To
better document the internal structure of the Mercedesstar quartz, two petrographic thin sections (each about
30 µm thick) were cut from the smaller sphere, parallel
to the two slices described above. This yielded a full disc
parallel to the first slice (S1, oriented perpendicular to
the quartz c-axis at the equatorial plane) and a half disc
cut from one of the remaining hemispheres (S2). Thus,
the perimeter of S1 contained six four-rayed star spots,
and the hemispherical circular edge of S2 contained two
three-rayed and two four-rayed star spots, as well as the
c-axis (Figure 12a).
With transmitted light, and without polarisers, no
remarkable features stood out within the quartz matrix,
except for randomly oriented segments of rutile needles
(Figure 12b). By rotating the slices between crossed
polarisers, both samples became uniformly dark.
Then, when rotating the analyser about 1° further, a
a c-axis b
Figure 12: (a) A diagram shows the orientation of two slices cut from the small Mercedes-star quartz sphere, with star spots
schematically represented along their rims. Slice S1 was cut perpendicular to the c-axis along a plane containing six four-rayed
star spots. Slice S2 was cut perpendicular to S1 along a meridian containing two three-rayed star spots and two four-rayed
star spots. (b) The general appearance of these slices, seen illuminated from behind and without light polarisation, shows only
randomly oriented segments of rutile needles (here, in slice S1). Photomicrograph by J.-P. Gauthier; field of view 4 × 3 mm.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 687
ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
chequerboard pattern with dark and bright tiles appeared
(Figure 13). The pattern reversed when the analyser
was rotated in the other direction. This behaviour is
expected for Brazil-law twin structure made up of rightand left-handed quartz.
This process is further illustrated using the slice cut
parallel to the quartz c-axis (S2). In Figure 14a, the
polariser is initially parallel to the base of the half-disc
(that is, perpendicular to the c-axis). The crossed polarisers are then rotated until the sample shows extinction
(Figure 14b). Finally, a slight rotation of the analyser
reveals the tiles and twin boundaries (Figure 14c),
which are oriented at around 50° from the horizontal.
This is very close to the inclination of the r or z planes
of the rhombohedron (i.e. 51°27'; Frondel 1962, p. 340).
Unfortunately, there is no crystallographic reference
for the horizontal slice (S1). We simply note that
extinction occurs when the analyser is parallel to the
twin edge (Figure 13b).
It is interesting to note that the tilt angle of the
normal (with respect to the horizontal) to the twin
boundaries is approximately 40° (again, see Figure
14c), which is also the latitude of the three-rayed star
spots (see Table I).
Figure 13: Viewed between
crossed polarisers, a slight
rotation of the analyser from the
extinction position reveals tiling
in quartz slices S2 (a) and S1 (b)
that is typical of Brazil-law twin
structure made up of right- and
left-handed quartz. Contrast was
enhanced to make the structures
more distinct. The double red
arrow indicates the position
of the analyser at extinction.
Photomicrographs by J.-P.
Gauthier; fields of view (a) 10 ×
10 mm and (b) 5 × 5 mm.
a b
c-axis c-axis
c-axis
a
b
c
Figure 14: Observation between crossed polarisers of quartz slice S2 reveals: (a) when the polariser axis (P) is first aligned with
the horizontal diameter (28 mm) of the half disc, the area appears bright, but (b) by turning the crossed polarisers about 50°,
the area becomes almost uniformly dark. (The yellow self-adhesive birefringent tape in a and b shows the rotation angle of the
polariser.) (c) By further rotating the analyser (A) by a few degrees, a tiled geometric structure becomes visible. The elongated
direction of the structural elements is parallel to the direction of the polariser in Figure 14b. The 40° angle between the red arrow
(analyser) and the horizontal corresponds to the latitude of the three-rayed star spots (see Table I), as well as the normal to the
rhombohedral faces. The red arrow in a and b indicates the position of the analyser. Photomicrographs by J.-P. Gauthier; field of
view 3.5 × 2.65 mm for image c.
688 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
DISCUSSION
Proposed Mechanisms of Asterism in
Mercedes-Star Quartz
Since we have excluded the presence of sets of invisible
parallel fibres leading to a scattering effect, and because
randomly oriented rutile needles alone cannot explain
a directional optical effect, we must consider a more
complex mechanism for the network of stars seen in
Mercedes-star quartz, involving both of the following
elements highlighted by the experimental observations
described above:
1. The presence of Brazil-law twin planes, as revealed
both by Brewster fringes and by tiling inside the
samples. Not directly visible without polarisers,
these can act as reflecting planes due to the change
in chirality of the quartz (from left to right, for
example), resulting in a slight change in refractive
index at the interface.
2. The illumination of some needles, thus playing an
obvious role in the formation of the star branches.
As the bright reflective markers of the branches, we
presume they operate in a second step to produce
the asterism.
Figure 15a shows a set of parallel Brazil-law twins
(in white) acting as mirrors, and a meridian plane
that is perpendicular to this set. With the light source
and observer positioned above the quartz sphere, any
vertical ray (blue or red) entering this meridian plane
will be reflected, by any twin of this set, within this
meridian plane. Now consider another set of randomly
oriented reflecting planes, none other than the mirror
planes observed on rutile needles. The preceding blue
and red rays can only be reflected back to the observer
by the planes of the rutile needles whose normal lies
in the meridian plane (optical paths in blue and red).
In any other situation—such as for rutile reflecting
planes whose normal is not in the meridian plane, or for
incident rays entering outside the meridian plane—the
twice-reflected rays usually will not reach the observer.
These conditions are very restrictive, but all rays
reaching the observer must cross the sphere on the rim
of a meridian plane, giving rise to a luminous branch
corresponding to multiple small planes of reflection.
Figure 15b shows, diagrammatically, three sets of
primary reflectors (blue), which are required to produce
a three-rayed star (yellow) on the rim of the three
meridian planes (grey) associated with these stars.
So that the branches do not extend beyond the top
of the hemisphere—otherwise a six-rayed star would
result from the three sets of reflectors—there must be
no reflector plane behind the plane perpendicular to
the meridian plane, shown in green on Figure 15a. We
discuss later if this condition may be satisfied.
Which Planes Are Involved? For the large quartz
sphere studied here, the only crystallographic information is the position of the c-axis. However, three sets of
reflecting planes are needed that are suitable to explain
Figure 15: (a) This diagram shows the optical path of light
rays propagating in a meridian plane that is perpendicular
to a set of twin planes (white) in Mercedes-star quartz. A
second reflection on a plane (red or blue; belonging to a rutile
needle) perpendicular to the meridian plane is necessary for
the rays to reach the observer (red or blue paths). The set of
rays propagating in (or close to) the meridian plane towards
the observer gives rise to a branch of a star (in yellow). (b) A
general model is depicted for producing a three-rayed star (in
yellow) due to the reflection of light from three sets of mirrors
(in blue) and then from small planes belonging to the needles
(not shown here). The branches of the star lie along three
great circles (meridian planes in grey) containing the incident
beam and the normals (blue arrows) to the reflecting planes.
In Mercedes-star quartz, the three-rayed stars are not seen
along the three-fold axis (c-axis), but they are visible at an
angle of about 50° from it.
a
b
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ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
the observed three-rayed stars (again, see Figure 15b),
and four planes for the four-rayed stars. It is worth
remembering that the three-rayed stars are not viewed
down a three-fold axis (c-axis) of the quartz.
Brazilian quartz (as well as quartz from other sources)
is known to exhibit ‘Brazil twins’, also called chiral or
optical twins (see, e.g., Schmetzer 1987; Lin & Heaney
2017). This is one of two categories of twins with parallel
axes known in quartz that is involved here, as shown
by the observations between crossed polarisers (Figures
13 and 14). The faces of the twinned volumes shown
in Figure 16a are crystallographic planes belonging to
the first-order prism m {10 0}, positive rhombohedron
r {10 1}, negative rhombohedron z {01 1} (see Figure
16b), basal plane c {0001} and triangular dipyramid s
{11 1}. Very often, they are manifested in the form of
thin, repetitive plates (polysynthetic twins parallel to r
or z planes; Frondel 1962, p. 387). In particular, the
lamellar structures in Figure 16c strongly resemble those
described by Sunagawa et al. (2009), showing the parallelograms that are seen in Brewster fringes.
The most frequently encountered and largest crystallographic planes in quartz usually correspond to the faces
of the rhombohedra r and z and the first-order prism m.
These are, therefore, the planes that we preferably choose
to explain the Mercedes-star quartz asterism. This choice
was not made at random. Indeed, as mentioned above,
in quartz the angle between the rhombohedral planes
r or z and the basal plane c is 51°47', very close to the
angular position of the three-rayed star spots relative to
the poles, north or south, at about 50° (Table I).
In addition, it has been assumed that each set of
reflecting planes lies on only one side of the vertical sphere
diameter (as shown in Figures 15 and 16c) to explain
the fact that the branches end at the star centre. It is not
possible to have an equivalent reflecting plane (either
rhombohedral or prismatic) on the other side of the c-axis,
simply because it is not also a binary (two-fold) axis. So
the plane on the other side is necessarily of a different
nature, and thus cannot reflect light the same way. Also,
it is probable that within a quartz prism, the lapidary will
cut a sphere that is centred within the crystal, if only to
obtain the maximum yield (Figure 16c).
Demonstrating the Involvement of These Planes.
Consider the observations between the rotation angles
0° and 50° shown in Figure 7a. In the first case, the
observer and the light source are in the direction of the
quartz’s three-fold axis (the c-axis). The observer does
not see any optical effect. By rotating the sphere upwards
by 50° around the horizontal axis in the plane of the
drawing, a three-rayed star appears, with a light beam
entering perpendicular to the surface of the sphere, thus
not deflected by refraction.
According to the description above, the branches of
the star will follow the meridians associated with three
great circles containing the incoming beam and each of
the normals to the reflecting planes. It is then necessary
to see if, after rotation by 50°, the chosen planes can
explain the appearance of the branches of the threerayed star in the observed directions.
Stereonet for Three-Rayed Stars. Stereographic projection (Box A) is a method of projecting points and angles
onto a circle on a two-dimensional diagram called a
stereonet (also known as a Wulff diagram; Bloss 1971;
a b c
Figure 16: (a) This sketch illustrates Brazil twin domains inside a quartz crystal, after Frondel (1962, p. 387). (b) A crystal model
displays the main faces that develop on quartz and their normals. Twin planes with the same orientations lie within the crystal.
(c) When ‘cutting’ a sphere from single-crystal Mercedes-star quartz, it is assumed that the Brazil twin planes do not extend
beyond the central axis.
690 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
b
This box focuses on angular displacements of the
normals to the twin planes when a quartz sphere
is rotated around an axis. Stereographic projection
can help follow the paths of the ends of normals that
originate at the centre Ω of a virtual sphere, with
their ends Q on the external surface of this sphere
(assumed to have a very large diameter compared to
the size of a quartz crystal). As described below, the
south pole P’ of the sphere plays a special role for
points in the northern hemisphere (and by analogy,
the north pole P has a similar role for points in the
southern hemisphere), making it possible to confine
all projections inside the stereographic circle.
By definition, the stereographic projection of the
end N of any normal ΩN of the northern hemisphere
is located at point Q, which is at the intersection of the
BOX A: STEREOGRAPHIC PROJECTION ON A STEREONET
equatorial plane and the line joining N to the south
pole P’ of the sphere (Figure A-1). In Figure A-1a, if
we consider all the points N on the circle (C) perpendicular to the west-east direction (W–E), characterised
by an angle NΩE =α, their stereographic projection is
represented in the equatorial plane by the curved red
line Q–Q’. Note that the stereographic projection of a
great circle (C’) is a line following the diameter of the
equatorial plane.
In Figure A-1b, for a point N on a great circle
(D) passing through the diameter W–E and tilted
by β with respect to the horizontal plane, its stereographic projection Q is located on a curved green
line, joining W to E.
On the stereonet (Figure A-1c), the two types of
lines (green and red) corresponding respectively to
Figure A-1: Stereographic projection can be used to
evaluate the angle δ between two normals ΩN and
ΩN’. Their ends N and N’ are located (a) on a circle
(C) perpendicular to the W–E axis, or (b) on a great
circle (D) containing this axis. (c) The stereographic
projections Q and Q’ of N and N’ are respectively
located on the same line (red or green) plotted
on the stereonet, making it possible to measure
the angular deviation α and β. In this example, the
projection of circles (C) and (D) illustrates the
angles they make with the horizontal plane (α = 50°
and β = 20°, represented by blue segments). The
angular deviation between ΩN and ΩN’ is δ = 80°,
counted on the red or green line.
a
c
b
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ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
a
b
Figure 17: In order to illustrate the correlation between star
spots and twin plane directions in Mercedes-star quartz, these
stereonets show the movement of the m, r and z poles of a
quartz crystal when rotated about the a2-axis, from an initial
position (in red) such as that drawn in Figure 7a (at 0°). (a)
A 50° rotation brings the poles of faces m and z (in green)
into the same position as shown in Figure 7a (at 50°) with
pole r at the centre of the diagram (i.e. in the direction of the
light source and observer, and coinciding with the centre of
the three-rayed star). (b) Similarly, a 90° rotation brings pole
m into the centre of the diagram, coinciding with the centre
of a four-rayed star in Figure 7a (at 90°). Arrows indicate the
movement of the different poles.
Shelley 1985). For this discussion, the light source and
the observer are always directed along the vertical axis
of the projected sphere (i.e. perpendicular to the plane
of Figure 17). We assume that the quartz c-axis <0001>
initially coincides with this direction, represented by
the centre of the stereonet. The other three axes of the
quartz are labelled a1, a2 and a3 along the edges of the
projection disc (the a3-axis is omitted from Figure 17
for clarity).
Figure 16b shows the crystal faces that are most likely
to be present within a quartz crystal as reflecting twin
planes. These are the r and z rhombohedral faces and
m faces of the first-order prism. With respect to the
c-axis, the normals to the faces projected on the stereonet
in Figure 17a—from left to right, z (1 01), r (10 1) and
z (01 1)—make an angle of about 51°47' with respect
to the c-axis (Frondel 1962, p. 340) and are, before the
rotation, on the same projection circle as the red points
in Figure 17a. The projection of the first-order prism
face m (10 0) is also labelled in red at the edge of the
stereonet.1 The situation in Figure 17a is similar to that
of Figure 7a for the 0° angle, where the black points
represent the star spots.
Starting from this configuration, rotation of the quartz
sphere around its a2-axis from bottom to top by 50° is
equivalent to the 50° position in Figure 7a. Then, the
poles (initial positions in red on Figure 17) of the r and z
faces move along ‘parallels’ of the stereographic projection (red arrows on Figure 17a), along which it is possible
to count 50° and fix their new positions. We see that the
pole r (in green) is then at the centre of the stereographic
projection in Figure 17a (i.e. facing the direction of the
α and β (represented by blue segments showing
angles α = 50° and β = 20°) are shown on a circle
gridded at 10° intervals (more detailed stereonets
are gridded at 2°, as in Figure 17 in the text). As
an example, if Q’ is the projection of N’ obtained
after rotation from ΩN to ΩN’, each projection line
provides the corresponding values of the angular
deviations δ between ΩN and ΩN’ (i.e. rotation of
δ = 80° shown in red and green, respectively, in
Figure A-1c).
The network of curves in a stereonet makes it
straightforward to follow the displacement of the
normals to the growth planes or twin planes as a
sample is rotated.
1 With rotation of 60° around the c-axis of the quartz, an
analogous situation would occur first with faces r, m and r,
and then with the m face of the first-order prism. Therefore,
if the three-ray star spot at A1 (longitude 0° for instance) in
Figure 5b is produced by a set of z-m-z faces, the next star spot
A2 (thus at the longitude 60°) will be produced by a set of
r-m-r faces. Thus, the use of stereographic projection is valid
for each three-rayed star.
692 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
incident light beam), and that the segments joining it
to the two poles z make an angle of about 130°. This
is exactly the situation in Figures 3c and 7a (centre),
where the star spot of a three-rayed star is at the centre
(position of green r) and the star branches are located on
three great circles containing the incident beam and each
of the normals to the reflecting planes. The intersection
of these three great circles corresponds to the normal to
the r plane. Note also that the angle of 130° between
the branches is not distorted by the stereographic projection, which allows measurement of the real angles on a
photograph taken perpendicular to the sphere surface at
the centre of a star (again, see Figure 3c).
Given the experimental errors, we propose that the
approximate measured value of 50° for the angular
positions of the three-rayed stars (points An and Bn in
Figure 5b) with respect to the north (P) and south (P’)
poles fits the theoretical angular value of 51°47' of the
r and z faces of the rhombohedra, with respect to the
horizontal (Frondel 1962, p. 340). Importantly, we have
shown that the normal to one face of the rhombohedron
is coincident to the direction of the light beam, when
looking at the star spots. Similarly, the angular value of
about 50° measured between crossed polarisers on the
twin planes with respect to the horizontal in Figure 14c
is close to the experimental value corresponding to the
tilt of the rhombohedral faces.
This demonstrates that our measurements are
consistent with light reflection on the twinned rhombohedral and prism faces, a rare phenomenon that we
propose is responsible for the three-rayed stars through
secondary reflections by appropriately oriented portions
of the rutile needles.
Stereonet for Four-Rayed Stars. Now consider rotation
around the a2-axis by 90° instead of 50°—that is, from
the 0° to 90° position in Figure 7a. The pole of the front
first-order prism m moves to the centre of the stereographic projection (Figure 17b), and the corresponding
plane becomes perpendicular to the incident beam (like
the r plane in the previous configuration). The poles m
of lateral planes of the first-order prism migrate on the
horizontal axis along the parallels (red arrows). The pole
of face r is replaced by that of the lower face z (initially
in the same position on the stereographic projection, but
in the southern hemisphere, represented by a dashed red
arc), and becomes symmetrical to it with respect to the
horizontal axis.
As shown in Figure 17b, the normals to the four planes
around the centre (r, z, m and m) are on great circles
passing through the direction of the incident beam (centre
Figure 18: The reflections from the rutile needles consist of
striae that are numerous and close together. Depending on
the orientation of the needles relative to the light source, they
are striated (a) almost parallel to the cross-section or (b)
tilted. Photomicrographs by J.-P. Gauthier; image widths 1.66
mm (a), 1.89 mm (b) and 0.67 mm for both insets.
a
b
of the stereographic projection). Thus, the four-rayed stars
are due to reflection on two non-adjacent m faces and a
couple of r and z faces, followed by secondary reflections
from the rutile needles. Regarding the weak intensity of
the horizontal branch, we assume, without being able
to prove it, that the prism faces of the twin interfaces
are poorly developed in (or perhaps absent from) the
earlier-described Mercedes-star quartz specimens, and
constitute only the edges of the twin lamellae.
Finally, the stereonets in Figure 17 show the strong correlation of star spot positions on Figure 7a (at positions 0°,
50° and 90°) with the normals to the m, r and z twin planes.
Reflection of Light by Rutile Needles
To the naked eye, the needles considered in the proposed
mechanism appear to shine continuously. At higher
magnification, the illumination of the rutile needles
reveals segments of closely spaced bright striae. The
brightness of the rutile segments is due to the reflection of light on planar features that are perpendicular or
oblique to the axis of a needle (Figure 18). This effect
can be emphasised by illuminating the inclusions with
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 693
ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
Figure 19: Illumination of the rutile needles with a laser
pointer emphasises their reflectivity. Photomicrograph by
J.-P. Gauthier; image width 2 mm.
Figure 20: The many illuminated rutile needles in this
sub-horizontal star branch are oriented roughly in the same
direction (see green arrow). In this case, the mirror striations
lie perpendicular to the axis of each needle, as in Figure 18a.
Needles that deviate from the general direction indicated by
the arrow correspond to the case of Figure 18b. The sample
is illuminated from the top of the photo, approximately
perpendicular to the arrow. Photomicrograph by J.-P.
Gauthier; image width 2.5 mm.
a laser pointer (Figure 19).
Even at high magnification, it is difficult to identify
the nature of the tiny reflecting planes on the needles.
Are they small facets on the surfaces of the needles,
glide planes or planar defects? The answer would
require further investigation beyond the scope of this
article. For now, it is sufficient to say that these features
contribute, as reflectors, to the asterism in Mercedesstar quartz.
Very often, the axis of a needle lies in the direction
of the light source (Figure 20) and along a branch of
the star. When that happens, the reflections of the striae
appear to be perpendicular to the needle axis (Figure
18a). Otherwise, the reflections are oblique (Figure 18b)
when a needle axis deviates from the orientation of the
light source.
The same kind of striae were seen with transmitted
light on the needles in the egg-shaped quartz. Without
further analysis, we suspect a similar cause for the
diasterism in that specimen, this time involving both r
and z faces, with light directed along the quartz c-axis.
In summary, the asterism in Mercedes-star quartz is
due to a rare combination of properties. In addition to
the characteristics of the rutile needles, the host quartz
must be finely Brazil-law twinned, with twinned sectors
exhibiting rhombohedral and prism faces. Figure 21
shows the faces involved in the first reflection from the
twins, for three-and four-rayed stars. In Figure 21a, the
normal to face r (in grey) is in the direction of a threerayed star spot, and the corresponding star branches
are produced by the primary reflections of twin planes
z, z and m (in orange). In Figure 21b, the face m (in
grey) is in the direction of a four-rayed star spot, whose
branches are produced by the lateral m planes and by
the upper and lower planes r and z, respectively (in
orange). If the quartz is rotated by 60°, the same observation will be made for the two types of stars, simply
by inverting the r and z notations.
CONCLUSION
The unusual asterism observed in Mercedes-star quartz
seems to exist only with the simultaneous presence of
Brazil-law twins and rutile needles. We therefore propose
a plausible mechanism that we can at least partially
b
Figure 21: Twin planes participating in the first reflection
needed to produce (a) three-rayed stars and (b) four-rayed
stars are shaded orange. When a three- or four-rayed star
centre is positioned at a star spot, the respective grey planes
are perpendicular to the incident beam of light.
a
694 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
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40–42, https://doi.org/10.15506/jog.2008.31.1.40.
validate through crystallographic observation and
reasoning. This unusual asterism arises from a doublereflection mechanism based on the following observations:
• Classical chatoyancy—light scattering on sets of
oriented acicular inclusions—was ruled out due to
the absence of parallel needles (even at sub-microscopic
scale, as validated using the water-drop test) and
by the fact that the branches stop at the centre of
each three-rayed star.
• The existence of ‘optical twins’ in Mercedesstar quartz was visible in slices and thin sections
cut from one of the samples through the presence
of Brewster fringes and tiling (Figures 11 and 13).
The occurrence of these twins induces the presence
of flat reflective surfaces due to the change of chirality
at the interface between the twin planes.
• This type of asterism has never been documented in
transparent quartz containing Brazil twins but
without rutile needles. Thus, the needles play a key
role in this phenomenon.
• While light scattering on oriented acicular inclusions
induces a six-rayed star in minerals with a three-fold
symmetry axis, the present phenomenon first requires
three sets of reflective planes not related to three-fold
symmetry, but which are due instead to Brazil twins.
• Randomly oriented rutile needles can intercept the
light reflected from the twin planes and send it back
towards the observer, provided that the entire light
path is in or near a meridian plane of the quartz
sphere. The secondary reflection inducing the
asterism is not due to the total surface area of rutile
needles, but from numerous, discrete, parallel small
reflective elements of the needles, the exact nature
of which we could not identify by optical microscopy.
• The locations of star spots, supported by stereographic projections, showed a strong correlation with
the directions of the normals to the r, z and m planes.
• Due to the random angular distribution of the rutile
needles and, thus, of their reflective elements, a high
needle density is required to produce enough reflections towards the observer to create the epiasterism
in Mercedes-star quartz. However, when very high
inclusion density makes the stone opaque, diasterism
cannot be observed.
This study represents a major step towards the understanding of Mercedes (three-rayed) stars in quartz. This
relatively rare and particularly complex optical phenomenon is related not only to inclusions, but also to the twinned
nature of otherwise transparent quartz. The requirement of
both a sufficient density of inclusions and Brazil twins means
that specimens are generally large (i.e. multi-centimetre
sized). Although less attractive than the usual asteriated
gems due to the diffuse appearance of the stars, Mercedesstar quartz is certainly an interesting curiosity for collectors.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 695
ASTERISM IN ‘MERCEDES-STAR’ QUARTZ
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Koivula, J.I. & Tannous, M. 2004. Lab Notes: Three rutilated
quartz cat’s-eyes. Gems & Gemology, 40(1), 63.
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boundaries in amethyst showing Brewster fringes.
Physics and Chemistry of Minerals, 17(3), 207–211,
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Ilakaka, Madagascar. Australian Gemmologist, 21(5),
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and symmetry of light spots and asterism in
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JoG.2006.30.3.183.
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International: Three-rayed asterism in quartz.
Gems & Gemology, 58(2), 249–252.
The Authors
Prof. Jean-Pierre Gauthier and Jacques Fereire
Centre de Recherches Gemmologiques,
U.F.R. des Sciences et des Techniques,
Université de Nantes,
2, rue de la Houssinière,
44072 Nantes Cedex 3, France
Dr Emmanuel Fritsch fga
Institut des Matériaux Jean Rouxel CNRS
(UMR 6502), University of Nantes,
BP 32229, F-44322, Nantes Cedex 3, France
Email: [email protected]
Thanh Nhan Bui
Rue du Compas, 47/4, 1070 Brussels, Belgium
Gem-A Members and Gem-A registered students receive 5% discount
on books and 10% discount on instruments from Gem-A Instruments
Contact [email protected] or visit our website for a catalogue
Schmetzer, K. & Steinbach, M.P. 2023. Gem Notes: Threerayed asterism in quartz: A multi-star network.
Journal of Gemmology, 38(6), 552–553, https://doi.
org/10.15506/JoG.2023.38.6.552.
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of natural quartz crystals. In: Growth and Morphology
of Quartz Crystals Natural and Synthetic. Terrapub
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chapter 6, pp. 125–132).
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title.3353.
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Chatoyance bei Edelsteinen. Lapis, 7(10), 25–27, 30, 38.
FEATURE ARTICLE
696 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Tektites (from the Greek tektos = molten)
are natural glasses that formed by meteorite
impacts on the earth’s surface. One of
the most well-known tektite varieties is
moldavite (Figure 1), which is named after the main
occurrence along the Vltava (or Moldau in German)
River in the Czech Republic. This tektitic glass originated during a meteorite impact around 14.8 million
years ago in the region of today’s Nördlinger Ries in
Germany (Schmieder et al. 2018). The impact created
temperatures that melted the rocks on the surface and
blasted the glassy droplets eastward over 400 km to
the upper reaches of the Vltava River and into Moravia
in today’s Czech Republic. Occasionally, moldavites
have also been found in Austria, Germany and Poland
(Brachaniec et al. 2014; Schmieder et al. 2018).
Moldavite has been used by humans since prehistoric times, as sharp-edged pieces for numerous tools
and as amulets. The earliest finds were in Austria in
the Gudenus cave near Krems, as well as near Willendorf; they date back to Palaeolithic time (Bayer 1921).
During the modern era, moldavite was particularly
popular during the Art Nouveau period (1890–1910).
Subsequently interest declined, coincident with the
increased use of green bottle glass as an imitation.
Figure 1: This moldavite shows a valuable ‘hedgehog’ shape
and comes from the Besednice locality in the South Bohemian
Region of the Czech Republic. Photo by Jan Loun.
Moldavite from Chlum,
Czech Republic: Mining
and Gem Properties
Tom Stephan, Štěpán Jaroměřský, Lukáš Zahradníček
and Stefan Müller
ABSTRACT: One of the most well known and popular natural glasses is moldavite, which formed
during a meteorite impact about 14.8 million years ago. Today, moldavite is mainly obtained from
the Czech Republic. In spring 2022, the authors visited the largest mine currently in operation, a
sand-and-gravel quarry near the small village of Chlum in the southern Czech Republic, where
moldavite is found as a by-product. This article reviews the formation and distribution of moldavite,
gives an overview of current mining activities and reports the gemmological characteristics of samples
collected by the authors.
The Journal of Gemmology, 38(7), 2023, pp. 696–707, https://doi.org/10.15506/JoG.2023.38.7.696
© 2023 Gem-A (The Gemmological Association of Great Britain)
Later, during the early 1950s and 1960s, moldavite
experienced a renaissance as a gem and collectable material, which spurred exploration to discover
additional mining sites in what is today the Czech
Republic. As a result of this geological survey, the
sand-and-gravel layers near Chlum nad Malší (hereafter,
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 697
Figure 2: The main
moldavite deposits in
the Czech Republic lie in
the southern part of the
country in the regions
of South Bohemia and
South Moravia. Moldavite
occurrences are also
known in Germany,
Austria and Poland. Map
adapted from Wikimedia
Commons (https://
commons.wikimedia.org/
wiki/File:Czech-regions.
svg).
~80 km to
Ries crater
Písek
Nové Hrady
Chlum and
Besednice
simply ‘Chlum’; Figures 2 and 3) in the South Bohemian
Region were identified as a source of moldavite
(Bouška et al. 1985).
Today, a large sand-and-gravel pit is actively being
operated near Chlum, and moldavite is recovered there
as a by-product. In addition, another smaller quarry
was opened in 2022 just north of the nearby village of
Besednice, where moldavite is the only product that
is mined (Dr Vít Kršul, pers. comm. 2023).
In May 2022, the authors had an opportunity to
visit the Chlum deposit in order to witness the mining
process and collect samples. In this article, we review
the formation of moldavite and its main localities, and
then examine the current mining techniques and describe
the results of our examination of the collected samples.
MOLDAVITE FORMATION
Moldavite most likely originated during the meteorite
impact responsible for the Nördlinger Ries crater in
Bavaria, Germany. This crater formed approximately
14.8 million years ago, during the Miocene (Bouška &
Konta 1999; Böhme et al. 2002; Di Vincenzo & Skála
2009; Schmieder et al. 2018; Schwarz et al. 2020).
Gentner (1971) performed age determination using
the K/Ar method, and showed that moldavite and the
Ries event both have the same age, thus linking their
origins. Graup et al. (1981) geochemically identified the
pre-impact sediments as upper freshwater molasse (i.e.
terrestrial clastic sedimentary rocks).
According to Pösges and Schieber (2009), the Ries
crater resulted from the impact of a meteorite with
a diameter of around 1 km that hit with a speed of
about 70,000 km/h, corresponding to the energy of
250,000 Hiroshima bombs. The impact body and the
surrounding rock were compressed to about a quarter
of their previous volume, creating a pressure of 4 Mbar
and temperatures up to 30,000°C. Melted rock materials
were ejected from the crater, and a mushroom-shaped
ash cloud formed to a height of 100 km. A total of 1,000
km3 of material was moved by the impact, with 150 km3
of rock ejected ballistically at up to 25 times the speed of
sound. While in flight, the ejected molten rock droplets
cooled rapidly and solidified into a glassy substance
(moldavite) that was thrown as far as 400 km eastward
in the direction of today’s Czech Republic. The resulting
crater had a diameter of about 15 km and an original
depth of 4 km, but it filled relatively quickly due to
gravitational collapse that occurred during subsequent
basement uplift and displacement by vertical and lateral
movements (see also Stöffler et al. 2013).
MOLDAVITE DEPOSITS
AND MINING
The moldavite deposits are located in southern Bohemia,
western Moravia and the Cheb Basin in the Czech
Republic, Lusatia in Germany, Waldviertel in Austria
(Trnka & Houzar 2002; Hanus 2016) and Lower Silesia
in Poland (Brachaniec et al. 2014). The largest deposits
FEATURE ARTICLE
698 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
are spread over the regions of South Bohemia and South
Moravia (Figure 2).
The most important moldavite deposits form a belt
of separate occurrences between Písek and Nové Hrady
(again, see Figure 2). The stones were concentrated by
gravity and water on the south-west margin of the South
Bohemian basin. They occur in sedimentary deposits
such as the Koroseky sands and gravels (KSG) in southern
Bohemia (e.g. Chlum; see Figure 4) and the Vrábče beds
(VB; Trnka & Houzar 2002). The dating of individual
sedimentary deposits that contain moldavite is a matter
of debate, as are the topographical, morphological and
chronological connections among the sites. The deposition of the moldavite-bearing sediments possibly occurred
during the Pliocene and early Pleistocene (Bouška &
Konta 1999), but the Miocene is often mentioned (Trnka
& Houzar 2002). Most of the sediments are colluvial-fluvial
sandy clays and/or clayey sands, which fill stream depressions and ravines or form dejection cones. Their thickness
is usually around a few metres. The main components of
these sediments are quartz and feldspar. At the Chlum
site, there is a broader association of moldavite with
gravel layers containing ‘heavy minerals’ such as zircon,
rutile, leucoxene and kyanite, while those discovered at
Besednice include andalusite, tourmaline and kyanite
(Trnka & Houzar 2002).
Various shapes and morphologies are typical for
moldavite from different localities. Stones from the
KSG deposits in southern Bohemia (e.g. Chlum and
Besednice) appear to be less rounded than those from
northern KSG locations such as Koroseky. The average
weight of VB stones is approximately 2 g, whereas KSG
moldavites tend to be larger. Alluvial transport of the
moldavite from the original point of impact affected the
size and, often, shape of the material. This transport
effect can also be observed on coexisting quartz pebbles,
which vary from angular fragments to rounded shapes
(Trnka & Houzar 2002). This leads to the assumption
that the KSG deposits are a polygenetic formation that
includes material of different origins. Moldavite from the
VB deposits typically shows deeper surface corrosion
lines and depressions formed by the chemical action
of groundwater in an acidic, permeable environment.
A simplified explanation is that after deposition in the
host sediments, the less-resistant zones of the moldavite
surfaces experienced greater etching due to the influence
of differently saturated waters (see Bouška et al. 1985).
Thus, the overall shape of moldavite pieces results
from a combination of the original fragmentation of
the melt, aerial flight, alluvial transport and, finally,
post-depositional chemical etching. A rare and quite
valuable shape of moldavite from the Besednice locality
resembles that of a hedgehog (again, see Figure 1), which
mainly results from post-depositional chemical etching.
The distinctive surface features of many moldavites are
especially useful because careful observation of them
Figure 3: This satellite
image (from Google Maps)
shows the locality of the
sand-and-gravel quarry
(red pin) near Chlum. The
additional white outlines
indicate officially recognised
moldavite deposits in the
Chlum-Besednice area
(taken from a map supplied
by Dr Vít Kršul, July 2023).
The illegal mining pits
mentioned in this article
were seen in the forest at
the top-centre of the image.
N
Map Area
µ
µ
Germany
Vienna
Prague
Czech Republic
Austria
Chlum
Besednice
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 699
Figure 4: (a) The sand-and-gravel quarry near Chlum is expansive. The sediments lie on top of gneissic bedrock (exposed as the
dark area on the far side of the smaller pit to the left). (b) Mining involves the use of excavators and trucks. A claystone horizon
(indicated by the arrow) forms a darker brown layer in the pit wall in the foreground. (c) Moldavite is found in subhorizontal
gravel layers. (The vertical lines are from the excavator used to mine the sediments.) Photos by T. Stephan.
b c
a
can help distinguish genuine moldavite from the many
glass imitations (e.g. Tay 2007; Tay et al. 2008; Hyršl
2015; Hanus & Hyršl 2018).
Today, moldavite specimens are housed in various
museums, research facilities and private collections
worldwide. The world’s largest public collection of
moldavite is found at the National Museum in Prague
(see Box A).
Moldavite Deposit near Chlum
The small village of Chlum nad Malší is located about
200 km south of Prague (Figure 2). North-east of the
village is a quarry where sand and gravel are mined
(again, see Figures 3 and 4). The approximately 700 ×
400 m pit contains several layers of sand and gravel, tens
of metres thick, lying on gneiss bedrock. The sand-andgravel layers are crossed by a claystone horizon at
several metres depth, but which does not run horizontally throughout the deposit. Moldavite is always found
above this horizon.
The sand-and-gravel layers are dug with excavators and taken by trucks to a nearby washing plant.
There the material is transported by conveyor belts to
various washing and sieving stations for sorting into
different grain-size fractions for industrial uses (Figure
5a). After removing the smaller fractions, the moldavite
is hand-picked at an intermediate facility (Figure 5b),
which we were not allowed to visit.
According to the on-site geologist, about 100,000–
150,000 tonnes of sand and gravel materials are mined
annually from the quarry. The average moldavite
recovery is 2.5–3 g/tonne, although the grade of
the different horizons varies. Most of the moldavite
specimens weigh 0.1–15 g each, but about 20% of them
are larger.
On the day of our visit, we were allowed to search a
particular area of the pit to a depth of about 5 m below
the surface. The sand layer in this area was interspersed
with several coarser-grained gravel horizons with clast
sizes up to about 1.5 cm (Figure 6). We found moldavite
specimens in these layers, and also on the surface,
especially along the transportation routes of the trucks.
Within 90 minutes of searching, we collected about
150 g of moldavite samples, consisting of fragments of
FEATURE ARTICLE
700 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
The National Museum in Prague contains the largest
public collection of moldavite in the world. Currently,
its tektite collection includes 20,702 moldavite
specimens from South Bohemia and 1,988 samples
from Moravia. It is valuable not only for the great
number of specific localities represented (140),
but also for showing such extensive variability in
morphology, colour and size. Here we review the
history and the most interesting moldavite specimens
in the permanent exhibition there, as well as some
samples that are stored in depositories. Another
(private) moldavite museum is located in Český
Krumlov, close to the moldavite deposits, and is
highly informative.
The tektite collection of the National Museum
was founded in 1930 by the purchase of František
Hanuš’s collection of about 6,000 moldavites of
excellent quality from Bohemian and Moravian
localities (Velebil 2020). Until then, the museum
had only a few moldavite specimens, including the
oldest documented one in the collection: a 38 g
specimen from Dolní Chrášťany that was acquired
by Josef Kořenský (1847–1938). This moldavite is
curiously perched on a flat pebble with which it was
allegedly found (Figure A-1). An open cavity on one
side of the moldavite is apparently the remnant of a
large gas bubble.
In 1936, the purchase of 350 moldavites from
Arnošt Hanisch of Třebíč expanded the National
Museum’s collection significantly with specimens
BOX A: MOLDAVITE IN THE NATIONAL MUSEUM OF THE
CZECH REPUBLIC
from Moravia. In subsequent years, additional
Moravian moldavites were purchased from collectors
J. Fiala and J. Krejčí, also of Třebíč. It is important
to realise that, at this time, moldavites were mostly
regarded as mere glass, so they did not become
very valuable until the mid-1960s. This is why the
collection continuously added fine specimens (e.g.
Figure A-2) during most of the twentieth century,
including the acquisition of 1,972 moldavite
specimens collected in 1972–1974 by B. Hrabě of České
Budějovice. In the following decades—during
the 1980s and especially after the millennium—
donations and purchases of moldavites from
collectors and mining companies became less
frequent. Nevertheless, one of the most valuable
of these donations took place in 2005 by collector
S. Langer, who provided 16 Moravian moldavites,
including some relatively large specimens.
Figure A-1: The oldest documented moldavite specimen in
the National Museum’s collection is a 38 g specimen from
Dolní Chrášťany, sitting on a pebble. Reportedly, the piece
was found like this. Collection of Josef Kořenský; photo by
D. Velebil.
Figure A-2: (a) Many of the moldavites at the National
Museum are displayed in their original showcases, which
have been restored. (b) The backlit specimens seen here
are a small sample of the more than 20,000 moldavites
in the museum’s collection (image width approximately
13 cm). Photos by L. Zahradníček.
a
b
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 701
Figure A-3: (a) The entire
collection of cut moldavites at
the National Museum consists
of these 42 stones. (b) These
two faceted samples (15.02
and 19.45 ct) were identified
as bottle glass in 2018 during
a review of the collection. (c)
Typical inclusions in bottle
glass are gas bubbles and
star-like devitrification features
(magnified 50×). Photos by
L. Zahradníček.
a
b c
The National Museum’s best moldavite
specimens are on display in its Hall of Meteorites (e.g. Figure A-2). The largest South Bohemian
moldavite in the collection is a 111 g specimen
from Strpí, near Vodňany (collection of B. Hrabě,
1972). The largest Moravian moldavite in the
collection weighs 235 g (collection of S. Langer,
2005) and comes from Kožichovice. The next
largest Moravian moldavites are also from Kožichovice: 147 g (collection of A. Hanisch, 1942),
124 g (collection of S. Langer, 2005) and 104 g
(collection of K. Žebera, 1980). Three noteworthy
moldavites in the National Museum’s collection
were found (and thoroughly documented) in
Central Bohemia: two came from the Kobylisy
sand quarry in Prague, and the third came from
another sand quarry in Jeviněves near Mělník.
These are extremely uncommon localities for
moldavite.
Moldavite most likely initially became popular
during the Land Jubilee Exhibition in Prague in
1891, which featured a display of jewellery set
with faceted moldavite and complemented with
pearls from the Vltava and Otava rivers. Unfortunately, interest in faceted moldavite promptly
declined because jewellery manufacturers in the
1890s did not take the gem seriously. In addition,
they often confused moldavite with cut green
bottle glass. Because of this, there are relatively
few (42) faceted moldavites in the National
Museum’s gem collection (Figure A-3a). Their
largest cut Bohemian moldavite weighs 48.25 ct
and the largest faceted Moravian one is 27.25 ct.
Unfortunately, it is now difficult for the museum
to acquire better cut moldavites, because collectors keep most such gems for themselves, and the
museum does not have the budget to purchase fine
specimens when they become available. Interestingly, during a review of the collection in 2016–2022,
several samples of cut bottle glass were discovered,
with typical air bubbles and star-shaped flux
inclusions (Figure A-3b, c).
FEATURE ARTICLE
702 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Figure 5: (a) The mined sediments are processed in this washing and sorting plant. (b) After screening out smaller size fractions,
the moldavites are hand-picked in the green building. Photos by T. Stephan.
a b
a few millimetres to pieces 4–5 cm long. Notably, we
found some flat, disc-shaped specimens, always with
the etched surfaces mentioned above. Special highlights
were a teardrop-like piece and a curved sample
(Figure 7), shapes which are relatively rare.
Illegal Mining
Moldavite is one of the most sought-after stones in
the Czech Republic. The deposits are located relatively
close to the surface, so it is easy to reach the moldavitebearing layers using hand tools. Also, it is not uncommon
to find moldavite on the surface of farmed fields,
especially after ploughing or heavy rains. These conditions are ideal for illegal mining. Moldavite is classified
as state property in the relatively few deposits recognised by mining authorities that have been documented
by official geological surveys. Elsewhere, moldavite
mining is not directly forbidden, but in the Czech
Republic digging is not allowed without official government permission, even on one’s own private property.
In short, without permits, mining is not allowed.
Despite these regulations, surface disturbances related
to the informal extraction of moldavite are common
(e.g. Figure 8).
In some agricultural fields and, especially, in the
surrounding forests, moldavite is mined by digging
shallow pits up to 2–3 m deep. The pits are dug
vertically until the moldavite-containing layer is
reached, and then excavated horizontally. Since the
pits are dug in soft sediments, the workings are
quite unstable. Furthermore, they are not properly
reclaimed after digging. The excavations also
damage the roots of forest trees, causing them to
die and/or be uprooted by the wind. In addition,
wild animals may fall into the deeper pits and be
unable to escape. There were so many illegal pits
in some areas that the nearby communities decided
to go through legal extraction procedures and then
restore the disturbed areas.
Illegal mining is a punishable offence, and police
Figure 6: (a) The authors were allowed to search for moldavite around the rim of the pit as deep as 5 m below the surface, where
we focused on areas of coarser grain size. (b) The dark specimen seen here is a 2.5-cm-wide moldavite, shown where it was
found in situ. Photos by T. Stephan.
a b
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 703
Figure 7: Among the moldavites recovered on the day of the authors’ mine visit were (a) one drop-shaped and (b) one curved
moldavite. These shapes are relatively rare. Photos by T. Stephan.
a b
Figure 8: Illegal mining for moldavite is a widespread problem, especially in the forests. (a) Hand-dug pits up to 2–3 m
deep are excavated vertically and horizontally, (b) causing damage to trees as well as leaving hazards for wildlife.
Photos by T. Stephan.
a b
officers frequently patrol the moldavite-bearing localities. In addition, the sand-and-gravel quarry near Chlum
has a modern security system. Penalties are mostly in
the form of bans.
MATERIALS AND METHODS
Four moldavite samples collected during the field trip
described above were polished on one side to measure
RIs with a standard refractometer. Their SGs were determined hydrostatically, and microscopic observations
were undertaken with a gemmological microscope
equipped with Zeiss Stemi2000 optics and an immersion
cell containing paraffin oil. Ultraviolet-visible-near
infrared (UV-Vis-NIR) spectra were recorded with a
PerkinElmer Lambda 950S spectrometer in the range
of 200–2500 nm. Chemical composition was measured
by energy-dispersive X-ray fluorescence (EDXRF) using
a Thermo Scientific ARL Quant’X spectrometer.
For comparison, several other samples from the
reference collection of the German Gemmological
Association (DGemG) were studied by the same
techniques described above, including four faceted
moldavites, three artificial green glasses (two faceted
and one rough), a green artificial glass that was donated
to DGemG as ‘green transparent obsidian’ and two
pieces of greenish slag glass (Figure 9).
RESULTS AND DISCUSSION
Standard Gemmological Properties
Refractive index measurements of the moldavite varied
from 1.480 to 1.500, and SG values were 2.33–2.35.
The RI values were in the known range for moldavite
(1.480–1.525), while the SGs were slightly low (cf.
2.36–2.44 g/cm3 density; Henn et al. 2020). By comparison, the RI and SG values of the artificial glasses were
1.510–1.522 and 2.42–2.51, respectively, and for the
slag glasses 1.622–1.629 and 2.80–2.84, respectively.
The inclusions in moldavite are unique and distinct
from those in other natural and artificial glasses (see,
FEATURE ARTICLE
704 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
e.g., Bouška et al. 1985). Our study samples often
contained tiny gas bubbles, usually smaller than 1 mm
diameter, but also some as large as 1 cm or more. The
gas bubbles were usually round, but some were oval to
elongated (Figure 10a–d). They were usually distributed
irregularly, but sometimes followed the swirls described
below. According to Žák et al. (2012), the gas inside the
bubbles is usually composed of carbon monoxide (CO),
carbon dioxide (CO2) and hydrogen (H2), with minor
amounts of other gases also present.
Often seen in the moldavites were distinct swirls (i.e.
flow structures, Figure 10a, b) that indicate variations in
chemical composition (Okrusch & Matthes 2014). Also
common were round to elongated, partial zig-zag to
curl-like inclusions of the silica glass lechatelierite (Figure
10a–c and e), which are diagnostic of moldavite (see,
e.g., Bouška et al. 1985) and are not found in imitations.
The lechatelierite inclusions represent molten quartz
grains and indicate temperatures of glass formation
above 1,730°C (Okrusch & Matthes 2014). The lechatelierite inclusions were more obvious when viewed with
crossed polarisers, and were often surrounded by a dark
cross-like extinction pattern (Figure 10f).
Figure 9: Samples from the DGemG reference collection analysed for this report include: one uncut (31.32 g) and two cut (2.79
and 7.65 ct) artificial glasses (left); four cut moldavites (top centre, 8.67−33.34 ct), as well as four rough moldavites (polished on
the back side, 0.61−5.97 g) that were collected during the 2022 field trip (bottom centre); two pieces of pale green slag glass (top
right, 5.88−7.68 g); and one artificial glass that was donated to DGemG as obsidian (bottom right, 14.22 ct). Photo by T. Stephan.
Artificial glass Slag glass
Artificial glass
(‘obsidian’)
Faceted moldavite
from DGemG
reference collection
Rough moldavite
self-collected from Chlum
The inclusions in the artificial glasses consisted
of typical round to oval gas bubbles as well as swirl
marks. The slag glasses were almost opaque, but gas
bubbles were observed close to and at the surface, as
well as a swirly colour distribution.
UV-Vis-NIR Spectroscopy
The colour of moldavite is due to iron (Bouška et al.
1985). Depending on the Fe content, the colour varies
from green to brownish green to brown. Most other
tektites are richer in Fe and are, therefore, typically
dark brown to black.
The optical spectrum of moldavite (Figure 11) is
dominated by a strong Fe2+ absorption band centred
around 1100 nm. Towards the UV range the absorption
increases strongly, and the two broad absorption
features form a transmission window at about 550 nm
in the green spectral region. By comparison, artificial
glasses resembling moldavite may show a much
different absorption spectrum (Hyršl 2015; Hanus
& Hyršl 2018), although some artificial glasses have
spectral features very similar to those of moldavite
(again, see Figure 11).
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 705
Figure 10: Typical inclusions in
moldavite, photographed in the
samples shown in Figure 9 that
were collected by the authors,
are: (a, b) round to oval gas
bubbles, as well as straight or
curved swirls (flow structures)
and elongated lechatelierite
inclusions showing high relief
(both magnified 40×); (c) oval
gas bubbles and lechatelierite
inclusions (magnified 32×);
(d) elongated, marquise-shaped
gas bubbles (magnified 10×);
and (e, f) a lechatelierite
inclusion shown in planepolarised (e) and crosspolarised light (f, surrounded
by an anomalous extinction
pattern; both magnified 20×).
All images were taken in
immersion. Photomicrographs
by T. Stephan.
a
c
e
b
d
f
Figure 11: The optical absorption spectrum of moldavite is
shown in comparison with spectra obtained from two artificial
glasses, one of which shows features quite similar to moldavite.
Optical Absorption Spectrum
Absorbance
Wavelength (nm)
Fe2+
~1100
Moldavite (0.61 g)
Glass (31.32 g)
Glass (2.79 ct)
4
3
2
1
0
400 600 800 1000 1200 1400
Chemical Analysis
Table I shows the results of EDXRF chemical analysis
of the moldavites analysed for this study, along with
the compositions of the green artificial glasses and slag
glasses shown in Figure 9.
Tektites such as moldavite typically have a chemical
composition similar to that of granite, with high SiO2
and Al2O3, lower K2O, CaO, MgO and Fe2O3, and traces
of Na2O. However, the artificial glasses and slag glasses
analysed for this study possessed a distinctly different
compositional range. The artificial glasses were of
the soda-lime (crown) type and had higher CaO and
Na2O contents than moldavite, while the slag glasses
were highly enriched in CaO. The compositions of the
artificial glasses and slag glasses obtained for this
study are consistent with unpublished reference
data from the databases of DGemG and the German
Foundation for Gemstone Research.
FEATURE ARTICLE
706 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Sample type Moldavite Artificial glass Slag glass
Description Rough (from Chlum) Faceted Rough and cut Cut ‘green obsidian’ Rough
Oxide (wt.%)
SiO2 62.37–76.57 76.69–77.38 61.33–70.81 69.69 40.63–40.93
Al2O3 10.33–12.57 11.41–11.60 1.04–7.86 2.24 17.84–17.97
K2O 3.30–3.93 2.92–3.14 2.95–6.59 0.66 2.08–2.10
CaO 2.63–3.21 2.77–3.32 8.65–11.02 8.93 23.77–24.21
Na2O 0.33–0.51 bdl 11.27–12.79 15.39 0.60–0.67
MgO 2.37–2.68 2.70–3.27 0.35–2.16 0.91 7.12–8.22
Fe2O3 1.81–2.14 1.58–1.65 0.02–1.68 0.82 0.21–0.32
Table I: Chemical composition of moldavite, artificial glass and slag glass from the DGemG reference collection.*
* The samples are shown in Figure 9. Abbreviation: bdl = below detection limit.
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as precious stones. Zeitschrift der Deutschen
Gemmologischen Gesellschaft, 34(3/4), 83–91.
Brachaniec, T., Szopa, K. & Karwowski, Ł. 2014. Discovery
of the most distal Ries tektites found in Lower Silesia,
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Di Vincenzo, G. & Skála, R. 2009. 40Ar–39Ar laser dating
of tektites from the Cheb Basin (Czech Republic):
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Gentner, W. 1971. Cogenesis of the Ries crater and
moldavites and the origin of tektites. Meteoritics, 6,
274–275.
Figure 12: (a) Natural uncut moldavite is set in this silver ring.
(b) Faceted moldavite is commonly mounted in jewellery with
Czech pyrope. Rings by Granát Turnov, the largest producer
of Czech garnet jewellery; photos by L. Aranyosiová, www.
CONCLUSION a b
Moldavite (tektite glass) was produced by a spectacular
meteorite impact event, and this origin adds to the
contemporary popularity of moldavite (and other
tektites). A resurgence in demand for moldavite began
in the 1950s and has been growing steadily since
then. In its rough state, moldavite is sought-after
by collectors. In addition, natural uncut moldavite
is often set in silver or gold, and faceted material is
sometimes mounted in jewellery with Czech pyrope
(e.g. Figure 12). Moldavite is especially popular in
tourist jewellery.
Gemmologically, moldavite can be identified by
a combination of RI and SG values, and it is easily
differentiated from artificial glasses by its characteristic
inclusion pattern. In cases of doubt, the absorption
spectrum can be helpful, and clear identification is
also possible by chemical analysis.
It is likely that the sand-and-gravel layers in the
Chlum-Besednice area of the Czech Republic will
continue to supply the market with moldavite for
the next several years.
MOLDAVITE FROM THE CZECH REPUBLIC
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 707
Graup, G., Horn, P., Köhler, H. & Möller-Sohnius, D.
1981. Source material for moldavites and bentonites.
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org/10.1007/bf00398615.
Hanus, R. 2016. Moldavite: Mysterious Tears from Heaven.
Granit, Prague, Czech Republic, 136 pp.
Hanus, R. & Hyršl, J. 2018. Distinguishing “synthetic” and
natural moldavite. Journal of Gems & Gemmology,
20(1), 14–25.
Henn, U., Stephan, T. & Milisenda, C.C. 2020.
Gemmological Tables for the Identification of
Gemstones, Synthetic Stones, Artificial Products and
Imitations/Gemmologische Tabellen zur Bestimmung
von Edelsteinen, Synthesen, künstlichen Produkten und
Imitationen. Deutsche Gemmologische Gesellschaft e.V.
and German Gemmological Association, Idar-Oberstein,
Germany, 42 pp.
Hyršl, J. 2015. Gem News International: Moldavites: natural
or fake? Gems & Gemology, 51(1), 103–104.
Okrusch, M. & Matthes, S. 2014. Mineralogie: Eine
Einführung in die spezielle Mineralogie, Petrologie und
Lagerstättenkunde. Springer, Berlin, Germany, xx +
728 pp., https://doi.org/10.1007/978-3-642-34660-6.
Pösges, G. & Schieber, M. 2009. Das Rieskrater-Museum
Nördlingen: Museumsführer und Empfehlungen zur
Gestaltung eines Aufenthalts im Ries. Verlag Dr.
Friedrich Pfeil, Munich, Germany, 128 pp.
Schmieder, M., Kennedy, T., Jourdan, F., Buchner, E. &
Reimold, W.U. 2018. A high-precision 40Ar/39Ar age
for the Nördlinger Ries impact crater, Germany, and
implications for the accurate dating of terrestrial
impact events. Geochimica et Cosmochimica Acta, 220,
146–157, https://doi.org/10.1016/j.gca.2017.09.036.
Schwarz, W.H., Hanel, M. & Trieloff, M. 2020. U-Pb dating
of zircons from an impact melt of the Nördlinger Ries
crater. Meteoritics & Planetary Science, 55(2), 312–325,
https://doi.org/10.1111/maps.13437.
Stöffler, D., Artemieva, N.A., Wünnemann, K., Reimold,
W.U., Jacob, J., Hansen, B.K. & Summerson, I.A.T.
2013. Ries crater and suevite revisited—Observations
and modelling. Part I: Observations. Meteoritics
& Planetary Science, 48(4), 515–589, https://doi.
org/10.1111/maps.12086.
Tay, T.S. 2007. From a Singaporean gem laboratory—
Moldavite: natural vs imitation? Australian
Gemmologist, 23(2), 76–78.
Tay, T.S., Atichat, W., Sriprasert, B. & Leelawatanasuk,
T. 2008. Moldavite: Natural or imitation. GIT2008:
Proceedings of the 2nd International Gem and Jewelry
Conference, Bangkok, Thailand, 9–12 March, 80–85.
Trnka, M. & Houzar, S. 2002. Moldavites: A review.
Bulletin of the Czech Geological Survey, 77(4), 283–302.
Velebil, D. 2020. Sbírka tektitů Národního muzea. Minerál,
28(3), 231–243.
Žák, K., Skála, R., Řanda, Z. & Mizera, J. 2012. A review
of volatile compounds in tektites, and carbon content
and isotopic composition of moldavite glass. Meteoritics
& Planetary Science, 47(6), 1010–1028, https://doi.
org/10.1111/j.1945-5100.2012.01369.x.
The Authors
Dr Tom Stephan
German Gemmological Association,
Prof.-Schlossmacher-Str. 1,
D-55743 Idar-Oberstein, Germany
Email: [email protected]
Stěpán Jaroměřský
Faculty of Science, Charles University,
128 43 Prague 2, Czech Republic
Lukáš Zahradníček
National Museum, Cirkusová 1740,
Prague 9 – Horní Počernice, Czech Republic
Stefan Müller
German Foundation for Gemstone Research –
DSEF German Gem Lab, Prof.-Schlossmacher-Str.
1, D-55743 Idar-Oberstein, Germany
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GEM NOTES
708 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
Origin of the Colour
and Dichroism in
Laurentthomasite
Isabella Pignatelli, Cristiano Ferraris and Dominik Schaniel
ABSTRACT: In 2020, laurentthomasite was described as a new gem material presenting remarkable
dichroism. Here its polarised optical absorption spectra are interpreted on the basis of compositional and structural data, indicating the presence of transition-metal ions (Fe2+, Fe3+ and Mn2+)
in different sites. Their possible contribution to colouration is discussed, but the spectral anisotropy
suggests that both the colour and dichroism of laurentthomasite arise from intervalence charge transfer
(IVCT) between Fe2+ and Fe3+. Similar anisotropy has been observed in the polarised spectra of other
Fe-bearing silicates with comparable optical properties and IVCT colour causes such as beryl, cordierite
and bazzite. Possible confusion with other blue-coloured gem materials is also discussed, as well as
the main differences useful for the rapid and correct identification of laurentthomasite.
The Journal of Gemmology, 38(7), 2023, pp. 708–716, https://doi.org/10.15506/JoG.2023.38.7.708
© 2023 Gem-A (The Gemmological Association of Great Britain)
Laurentthomasite, Mg2K(Be2Al)Si12O30, is a
relatively new and rare gem material that was
shown for the first time at the Tucson gem and
mineral shows in 2020, where both rough and
faceted samples were exhibited (e.g. Figure 1). This
complex silicate is of particular gemmological interest
due to its deep blue colour and strong dichroism (Figure
2). It was approved as a new mineral species in 2019 by
the International Mineralogical Association, following
a proposal submitted by Ferraris et al. (2019). It is
named in honour of French geologist and mineral dealer
Laurent Thomas, who collected it in Madagascar. The
name ‘thomasite’ was initially proposed, but since it
could have been confused with thaumasite (especially in
French), the name was amended to laurentthomasite in
order to acknowledge his discovery of this new species.
Given the rarity of laurentthomasite, only a few
studies of it have been published. Ferraris et al. (2020)
described its physical properties, chemical composition
and structure, and they deposited the holotype at the
Muséum National d’Histoire Naturelle (MNHN) in Paris.
Ounorn et al. (2020) published the results of standard
gemmological testing on two oval mixed-cut gems and
provided polarised ultraviolet-visible-near infrared
Figure 1: These rough and cut samples of laurentthomasite
were seen at one of the Tucson gem and mineral shows
in 2020. The faceted stones weigh 0.73, 0.94 and 0.76 ct
(from left to right), and the crystal is 2.2 cm in height.
Photo by Jeff Scovil.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 709
COLOUR ORIGIN OF LAURENTTHOMASITE
Figure 2: This crystal specimen of laurentthomasite displays
striking dichroism in deep blue looking down the c-axis and
yellow in directions perpendicular to it. Photos by Jeff Scovil.
(UV-Vis-NIR) spectra, but they did not discuss the
spectral features. JGGL (2020) presented gemmological, chemical and spectral data on laurentthomasite,
and compared it to grandidierite (another rare blue gem
material from Madagascar).
In this study, we recorded polarised absorption
spectra in order to understand the origin of colour and
dichroism of laurentthomasite, taking into account the
structural description given by Ferraris et al. (2020)
and the spectra of other silicates having similar optical
properties (e.g. beryl, cordierite and bazzite).
CRYSTAL CHEMISTRY OF
LAURENTTHOMASITE
Laurentthomasite is a Be-bearing mineral, and the
presence of this element was first confirmed by laserinduced breakdown spectroscopy. Then inductively
coupled plasma mass spectrometry, as well as inductively coupled plasma optical emission spectrometry,
were used to quantify the contents of Be, major oxides,
trace elements and rare-earth elements (Ferraris et al.
2020). The resulting chemical data (see Table I) indicate
the presence of four transition-metal ions—Fe2+, Fe3+,
Mn2+ and Sc3+—but only the first three of these can
affect the colour and dichroism of laurentthomasite.
Although Sc3+ is a transition metal of the d-block, it
has no d electrons left over. For this reason, scandium
absorbs no visible light and does not play a role in the
colouration of minerals.
To better understand the relationships between the
locations and occupancies of cationic sites and associated spectroscopic data, here we briefly explain the
structure of laurentthomasite (Figure 3). It crystallises in the hexagonal system (space group P6/mcc,
cell dimensions a = 9.9580(1) Å and c = 14.1492(1)
Å), and it has a structure built up of double six-membered rings [T(1)12O30]. Thus, it is a cyclosilicate, and
it belongs to the milarite group. The rings are stacked
along the c-axis, forming channels. Each T(1) tetrahedron of the rings shares three corners with adjacent
T(1) tetrahedra and one corner with a T(2) tetrahedron. The latter shares all corners with T(1) tetrahedra
and two edges with A octahedra, giving rise to a
framework. B sites are sandwiched between adjacent
A octahedra and are vacant in laurentthomasite. C sites
are surrounded by 12 oxygen atoms that occur at the
centre of the channel formed by the [T(1)12O30] rings.
Chemical analyses coupled to the structural refinement
indicate that: (1) T(1) tetrahedra are occupied by Si,
whereas T(2) tetrahedra are mainly occupied by Be and
Al; (2) A sites contain Mg, Sc, Fe and Mn; and (3) C
sites essentially contain K with low amounts of Na, Ca
and Ba. Mössbauer spectroscopy revealed the presence
of both Fe2+ and Fe3+ located in the A and T(2) sites,
respectively (Ferraris et al. 2020).
Considering that the general formula of milaritegroup minerals is A2B2C[T(2)3T(1)12O30](H2O)x (with
0<x<2), the empirical formula of laurentthomasite
calculated on 30 oxygen atoms can be written as
(Mg0.86Sc0.54Fe2+
0.34Mn0.26)(K0.89Na0.05Y0.02Ca0.01Ba0.01)
[(Be2.35Al0.50Mg0.11Fe3+
0.03)(Si11.90Al0.10)O30](H2O)x. Reports
about water content are controversial, because it is not
clearly understood where water occurs in the structure
of minerals belonging to the milarite group. Some
research has shown that H2O is an important constituent at the B sites, but H2O can also be occluded and not
bonded directly to any cation (Hawthorne et al. 1991;
Hawthorne 1992; Gagné & Hawthorne 2016). Moreover,
water content can vary from one sample to another;
SiO2 73.10 MgO 4.01
Al2O3 3.11 ZnO 0.04
Sc2O3 3.78 CaO 0.07
Y2O3 0.22 BaO 0.16
TiO2 0.02 BeO 6.02
FeO 2.69 Na2O 0.15
Fe2O3 0.19 K2O 4.30
MnO 1.91 Total 99.77
* Data from Ferraris et al. (2020); Fe2O3 recalculated from
Mössbauer data.
Table I: Chemical composition (in wt.%) of laurentthomasite.*
a b
GEM NOTES
710 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
a b
Figure 3: Two diagrams depict the crystal structure of laurentthomasite projected down (a) the c-axis and (b) the a-axis. The
different cationic sites are labelled T(1), T(2), A, B and C; oxygen atoms are in red. These drawings were made using VESTA
software (Momma & Izumi 2011).
Ferraris et al. (2020) did not detect water in their sample,
whereas the FTIR spectra provided by JGGL (2020) and
Ounorn et al. (2020) revealed weak absorption bands at
approximately 3550, 3447 and 3253 cm–1. Although the
cited authors did not explain these spectral bands in their
publications, they are probably related to the presence
of water. This difference in results is not surprising,
because some samples of milarite-group minerals are
anhydrous, while others contain small amounts of water
(Gagné & Hawthorne 2016).
GEOLOGICAL SETTING
To date, laurentthomasite occurs at only one locality,
about 40 km east of the village of Betroka, within Toliara
Province in southern Madagascar. The mine is situated
in a rural area called Beravina, close to the small village
of Ambaro (23°21'00\" S, 46°25'00\" E).
This area is underlain by migmatitic paragneisses
and orthogneisses containing lenses of granites and
marbles (Rakotonandrasana et al. 2010). Laurentthomasite
formed in a granitic pegmatite hosted within high-grade
metamorphic rocks such as amphibolites and migmatites. The pegmatites in this area are enriched in Sc,
which explains the remarkable content of this element
in laurentthomasite (3.78 wt.% Sc2O3; see Table I).
Scandium is quite rare in terrestrial minerals and, above
all, in gems.
Only very limited areas of the pegmatite contain
laurentthomasite, which has been found together with
orthoclase (up to 5 cm), quartz and rare green apatite.
Also present were rare tabular crystals of grey-tan
corundum that were less than 1 cm long (Ferraris et
al. 2020).
MATERIALS AND METHODS
Six crystals of laurentthomasite were obtained by
Laurent Thomas in Madagascar and deposited at the
MNHN in Paris. One of them was analysed for this
study (Figure 4). It is 4.41 mm tall with a width of 3.35
mm. Its hexagonal prismatic habit is not complete, with
only relict prismatic faces and one pinacoidal face. We
chose to obtain UV-Vis-NIR spectra from this sample
because it was less included than the others and easier
to orient, thanks to the faces. The sample was neither
sliced nor embedded in resin in order to be used in
further investigations.
Polarised optical absorption spectra were recorded
in two directions in the 350–1700 nm range at room
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 711
COLOUR ORIGIN OF LAURENTTHOMASITE
temperature using a Shimadzu 3600 spectrometer. The
spectra were taken with the electric field vector E of the
incident light perpendicular (E┴c) and parallel (E||c)
to the c-axis (i.e. the beam was directed parallel and
perpendicular to the c-axis, respectively). The measurements were carried out with a spectral slit width of 2
nm and a step size of 0.1 nm.
RESULTS AND DISCUSSION
The examined crystal showed dissolution marks, in
particular hexagonal etch pits visible on the pinacoid
(Figure 5a), as described by Koivula and Renfro (2022).
It also contained eye-visible orangey brown inclusions
of Fe-bearing minerals not yet identified (Ferraris et al.
2020; see, e.g., Figure 5b).
Laurentthomasite is characterised by strong
pleochroism (Figures 2 and 4). Being uniaxial, it can have
only two pleochroic colours (dichroism). The optic sign
of laurentthomasite is positive, so its optical indicatrix
is an ellipsoid, where the optic axis coincides with the
crystallographic c-axis. As shown in Figure 4, it appears
blue in the ordinary ray (ω), which defines the circular
section of the indicatrix in the plane perpendicular to
the optic axis, and yellow in the extraordinary ray (ε, i.e.
in the oval section of the indicatrix in the plane parallel
to the optic axis).
The optical absorption spectra of laurentthomasite
show a broad absorption in the yellow-to-red portion of
the visible range in the E┴c direction, in comparison to
the weaker visible-range absorption in the E||c spectrum
(Figure 6). This explains the intense blue colour of this
mineral and its dichroism.
E c Spectrum
The E┴c spectrum (Figure 6) has a steep UV absorption edge extending into the violet portion of the visible
range. This feature could be attributed to O2–
–Fe3+
charge transfer or point defects (Fritsch & Rossman 1988;
Shang et al. 2022 and references therein). The spectrum
also shows a broad, intense absorption covering the
near-infrared and part of the visible range, decreasing
to a minimum around 500 nm. Thus, combined with
the absorption in the violet spectral range, the mineral
appears blue. A tentative deconvolution of the spectrum
with Gaussian bands is available in The Journal’s online
data depository to support the following discussion.
In the near-infrared range, two bands appear at around
Figure 4: (a) A crystal diagram
for laurentthomasite shows the
relationships between habit, optical
indicatrix and the strong dichroism,
which appears (b) blue for the
ordinary ray (ω, i.e. viewed parallel
to the c-axis) and (c) yellow for
the extraordinary ray (ε, i.e. viewed
perpendicular to the c-axis). Both
images are of the same sample
(4.41 × 2.85 × 3.35 mm), which was
analysed for this study. Photos by
Emmanuel Wenger.
a
b
c
GEM NOTES
712 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
909 and 1300 nm. (Note that the absorption between
750 and 1000 nm is saturated due to the thickness of
the crystal used, so the peak position at 909 nm was
derived from the spectral deconvolution, as described in
The Journal’s online data depository.) According to the
literature (Goldman et al. 1977; Amthauer & Rossman
1984), these two bands correspond to crystal-field transitions due to the Eg states of octahedral Fe2+, as in Fe-rich
cordierite. By comparison with Fe-bearing blue beryl,
the strong absorption maximum around 909 nm can
be attributed to octahedral Fe2+, but it is outside the
visible region, so it does not contribute to colour in
laurentthomasite (Groat et al. 2010; Shang et al. 2022
and references therein).
The broad tail that extends through the yellow-to-red
part of the spectrum (i.e. between 570 and 780 nm)
was deconvoluted into two bands at 694 and 588 nm,
before reaching the minimum at approximately 500 nm.
According to their positions and widths, the two bands
are ascribed to Fe2+–Fe3+ intervalence charge transfer
(IVCT), as observed in other minerals (Amthauer &
Rossman 1984; Mattson & Rossman 1987; Burns 1993).
IVCT is directional and causes strong pleochroism, as
previously documented in beryl, cordierite, lazulite,
bazzite etc. (Fritsch & Rossman 1988; Taran & Rossman
2001; Taran et al. 2017). Taking into account the
anisotropy of the absorption spectra, the vector between
the cations involved in IVCT should be oriented
perpendicular to the c-axis.
According to the Mössbauer analysis and structural description given by Ferraris et al. (2020), Fe2+
is in octahedral coordination in the A sites, whereas
Fe3+ occupies the neighbouring tetrahedral T(2) sites.
This confirms that the Fe2+–Fe3+ charge transfer takes
place in the plane perpendicular to the c-axis (Figure
3). Moreover, each T(2) site shares two edges with two
adjacent A sites, and the A–T(2) distance is 2.87 Å.
This proximity favours Fe2+–Fe3+ IVCT processes, which
have low probability of occurring in structures with
relatively long distances between cationic sites, such
as in garnet (Taran et al. 2007).
Following the procedure applied by Groat et al. (2010)
for dark blue aquamarine and beryl, it is possible to
estimate the amount of Fe involved in the IVCT process.
This amount is determined using the intensity of the
IVCT band and the Beer-Lambert law. From the experimental data and deconvolution, the IVCT band at 694
nm has an absorbance of 0.71 for a sample thickness
of 4.41 mm. The molar coefficient for IVCT interaction
in laurentthomasite is unknown, as in beryl. For this
reason, we used a typical molar absorption coefficient
for IVCT in silicate minerals (i.e. 150) as previously
done by Groat et al. (2010). Using the density of laurentthomasite (2.66 g/cm3), we calculated 0.011 moles per
litre of Fe pairs (i.e. 0.045 wt.% Fe) were involved in
the IVCT interactions.
The minor shoulders at 377, 424 and 442 nm were
also reported by Ounorn et al. (2020) and can be
attributed to Fe3+ in octahedral sites (Amthauer &
Rossman 1984; Taran & Rossman 2001; Groat et al. 2010;
Liu & Guo 2022; Shang et al. 2022). Thus, the presence
of these three bands suggests that Fe3+ can occupy
both octahedral and tetrahedral sites, even though the
Mössbauer study shown by Ferraris et al. (2020) on a
bigger sample revealed only the presence of IVFe3+. (It
should be noted that Mössbauer data were not recorded
on the sample analysed in this study because of the
sample’s small size and the presence of Fe-bearing
inclusions.) However, the bands at 424 and 442 nm
could be caused by a combination of Fe3+ and Mn2+
a b
100 µm 200 µm
Figure 5: (a) Hexagonal etch pits are visible on the pinacoidal face of the analysed laurentthomasite sample. (b) Orangey brown
inclusions of Fe-bearing minerals are shown here in another, more-included sample of laurentthomasite. Photomicrographs by
Emmanuel Wenger.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 713
COLOUR ORIGIN OF LAURENTTHOMASITE
(Webster 1983; Liu & Guo 2022). In fact, they have also
been observed in the spectra of Mn-bearing synthetic
spinels (Webster 1983). However, Fe3+ and Mn2+ do not
contribute significantly to the colour of laurentthomasite
because their absorptions are too weak and/or too close
to the UV region (Liu & Guo 2022; Shang et al. 2022).
The effect of IVCT on the colour of laurentthomasite is
more important than that caused by these cations when
they are isolated (Fritsch & Rossman 1988).
E||c Spectrum
The E||c spectrum (Figure 6) has an absorption edge in
the UV range that extends into the blue end of the visible
region and, in the absence of other strong absorptions
in the visible range, leads to the yellow colour attributed to O2––Fe3+ charge transfer, as in heliodor (Fritsch
& Rossman 1988).
The pair of bands in the IR region near 1110 and 1308
nm look similar to those of Fe2+-bearing silicates (e.g.
cordierite and bazzite), but they are shifted towards
higher wavelengths (Taran et al. 2017). They can be
attributed to octahedral Fe2+ (Goldman et al. 1977;
Khomenko et al. 2001; Taran & Rossman 2001; Taran
et al. 2017), and their shift could be due to the larger
octahedral site in laurentthomasite (cf. Taran et al. 2017).
Role of Sc
Although laurentthomasite also contains Sc, it cannot
affect colour, as mentioned above. This is also the case
in another Sc-rich cyclosilicate (i.e. bazzite). Its structure
is an analogue to that of beryl in which nearly half
the octahedral sites are occupied by Sc3+ replacing
Al (Armbruster et al. 1995). Like laurentthomasite,
bazzite shows strong dichroism (ω = greenish yellow
Figure 6: Polarised UV-Vis-NIR absorption spectra of laurentthomasite are characterised by a strong dichroic (E┴c >> E||c)
absorption in the visible range, which is caused by IVCT transition between Fe2+ and Fe3+. The path length of the beam was
3.35 mm for E||c and 4.41 mm for E┴c.
800
Wavelength (nm)
400 600 800 1000 1200 1400 1600
Absorbance
2.5
2.0
1.5
1.0
0.5
0
Optical Absorption Spectra
E┴c
E||c
1110 1308
442
424
377
694
1300
909
VIFe3+ + Mn2+
Fe2+– Fe3+IVCT
VIFe2+
GEM NOTES
714 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
and ε = blue) that is not due to Sc but to IVCT between
Fe2+ and Fe3+ occupying different cation sites (Taran
et al. 2017).
Comparison with Other Blue Gemstones
Showing Pleochroism
At first glance, laurentthomasite may be confused
with cordierite (iolite), which is more often found in
Madagascar. With careful analysis, it is possible to
distinguish them easily. Although cordierite occurs
as pseudo-hexagonal prisms, and its density is close
to that of laurentthomasite, these two minerals
have three main differences. (1) Their pleochroism
differs. Due to their different symmetries, laurentthomasite is dichroic, while cordierite is trichroic
and shows colourless-to-pale yellow, violet and light
blue colours for the three crystallographic directions.
(2) Their optical properties also differ. The crystal
system of cordierite is orthorhombic, so it is a biaxial
mineral, whereas laurentthomasite is uniaxial. (3)
Their hardness can be useful to distinguish them
rapidly with a simple scratch test when appropriate.
Cordierite has a Mohs hardness of 7–7½, while
laurentthomasite’s hardness is 6. They can also be
distinguished by comparing their Raman spectra;
that of laurentthomasite is presented in Ferraris
et al. (2020).
In addition, it is possible that laurentthomasite
could be confused with blue sapphire (also found in
southern Madagascar), but sapphire shows only weak
pleochroism (ω = slightly violetish blue, ε = slightly
greenish blue; Hughes 1997). The higher density and
hardness of corundum are the main features facilitating its distinction from laurentthomasite.
Another blue gem material from southern
Madagascar is grandidierite. Compared to laurentthomasite, it has a greater hardness (7½) and density
(2.85–3.09 g/cm3; JGGL 2020). Moreover, grandidierite is orthorhombic, so it is biaxial and trichroic
in bluish green, deep green and colourless (Sun et al.
2019). In addition, grandidierite has perfect cleavage
on {100} and {010}, and the crystals are usually
anhedral, elongated and strongly corroded.
Laurentthomasite could appear similar to benitoite,
especially after cutting, because the different crystal
habits that are helpful for recognising them in the
field are not present. These minerals have other
common features: both have a Mohs hardness of 6;
both are hexagonal and, thus, optically uniaxial (with
a positive sign) and display dichroism. However, the
dichroic colours for benitoite are ω = colourless and
ε = blue to violetish blue. Benitoite and laurentthomasite
are also easily differentiated by their density (3.68
vs 2.66 g/cm3), RIs (1.757–1.804 vs 1.555–1.560) and
birefringence (0.046 vs 0.005).
Tanzanite is another blue mineral with strong
pleochroism. Being orthorhombic, it is biaxial
and trichroic. Thus, its optical properties and
habit preclude confusion with laurentthomasite.
Moreover, its higher density (>3 g/cm3) is the main
distinctive feature of tanzanite in comparison with
laurentthomasite.
Bazzite (from Norway and Kazakhstan) and Santa
Maria aquamarine (from Brazil) have dichroism
similar to that of laurentthomasite (cf. Segura & Fritsch
2013; Taran et al. 2017). They are all hexagonal and
uniaxial, but they can be differentiated by optic sign
and RI values. In addition, the density and hardness
of laurentthomasite are lower than those of bazzite
and Santa Maria aquamarine. Another difference that
may be useful in the field is morphology. All of them
develop a hexagonal prismatic habit, but laurentthomasite crystals appear stubby, with variable
height that usually does not exceed 2.5 cm (Ferraris
et al. 2020).
CONCLUSIONS
Polarised optical spectroscopy indicates that Fe is
the most important chromophore in laurentthomasite, although it also contains Mn. The spectra show
strong dichroic (E┴c >> E||c) absorption in the visible
range caused by IVCT transition between Fe2+ and
Fe3+. This anisotropy explains why laurentthomasite
appears blue for E┴c and yellow for E||c, and suggests
that the vector between the ions involved must be
oriented perpendicular to the c-axis. The vector that
fulfils this conditions is that between Fe2+ in octahedral A sites and Fe3+ in tetrahedral T(2) sites. However,
weak bands in the sample we analysed at 377, 424 and
442 nm indicate that Fe3+ can also occupy octahedral
A sites. Calculations indicate that the concentration
of Fe involved in the IVCT process is 0.045 wt.%,
which corresponds to about 2% of the total Fe in
laurentthomasite.
After cutting, laurentthomasite can look similar
to other blue gemstones, especially ones with strong
pleochroism, such as grandidierite or Santa Maria
aquamarine. For this reason, it is important to perform
standard gemmological tests and analyse accurately
the optical properties (e.g. optic sign and RI values)
in order to unambiguously identify a stone.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 715
COLOUR ORIGIN OF LAURENTTHOMASITE
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GEM NOTES
716 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
FEATURE ARTICLE
The Authors
Dr Isabella Pignatelli
Université de Lorraine, Georessources UMR 7359
UL-CNRS, BP 70239, 54506 Vandœuvre-lès-Nancy
cedex, France
Email: [email protected]
Dr Cristiano Ferraris
Institut de Minéralogie, de Physique des Matériaux
et de Cosmochimie, UMR 7590, Muséum National
d’Histoire Naturelle, CP 52, 61 rue Buffon,
75005 Paris, France
Dr Dominik Schaniel
Université de Lorraine, Laboratoire de
Cristallographie, Résonance Magnétique et
Modélisation (CRM2) UMR 7036 UL-CNRS, BP
70239, 54506 Vandœuvre-lès-Nancy cedex, France
Acknowledgements
The authors are grateful to Dr Emmanuel Wenger for
photos of laurentthomasite, as well as to Prof. Gaston
Giuliani for helpful discussions.
Sun, N., Li, G., Li, X. & Zhang, B. 2019. Gemmological
characteristic of grandidierite from Madagascar. Journal
of Gems & Gemmology, 21(3), 37–41, https://doi.
org/10.15964/j.cnki.027jgg.2019.03.005.
Taran, M.N. & Rossman, G.R. 2001. Optical spectroscopic
study of tuhualite and a re-examination of the
beryl, cordierite, and osumilite spectra. American
Mineralogist, 86(9), 973–980, https://doi.org/10.2138/
am-2001-8-903.
Taran, M.N., Dyar, M.D. & Matsyuk, S.S. 2007. Optical
absorption study of natural garnets of almandineskiagite composition showing intervalence
Fe2++Fe3+→Fe3++Fe2+ charge-transfer transition.
American Mineralogist, 92(5–6), 753–760,
https://doi.org/10.2138/am.2007.2163.
Taran, M.N., Dyar, M.D., Khomenko, V.M. & Boesenberg,
J.S. 2017. Optical absorption, Mössbauer, and FTIR
spectroscopic studies of two blue bazzites. Physics and
Chemistry of Minerals, 44(7), 497–507, https://doi.
org/10.1007/s00269-017-0877-2.
Webster, R. 1983. Gems: Their Sources, Descriptions and
Identification, 4th edn. Butterworths & Co., London,
1,044 pp.
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CONFERENCES
718 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Conferences
5TH ITALIAN NATIONAL CONFERENCE OF GEMMOLOGY
Italy’s 5th National Conference of Gemmology took
place on 26–27 June 2023 at Sapienza University of
Rome (Figure 1). It was organised by Drs Giovanni B.
Andreozzi, Ferdinando Bosi and Michele Macrì of
Sapienza University of Rome, and also by Paolo Minieri
of IGR – Rivista Italiana di Gemmologia/Italian
Gemological Review. More than 220 participants registered for the two-day event, which had a theme of
‘Yesterday, Today, Tomorrow: Gemmology between
Research, Market and Politics’. Most of the presentations were in English, and simultaneous translations
were provided in Italian or English. The event was
accompanied by an exhibition of fine gemstones
crafted by master cutter Luigi Mariani (Figure 2).
The conference began with several introductory
addresses by dignitaries and the conference organisers,
during which attendees learned that Italy’s inaugural
National Conference of Gemmology occurred in 2010
in Bari, and subsequent events took place in Florence,
Naples and Ferrara.
Three presentations offered general reviews of
gemmological topics. Dr Thomas Hainschwang (GGTL
Laboratories, Balzers, Liechtenstein) discussed current
challenges faced by gemmological laboratories. For
coloured stones, these include: authenticating meleesized gems in parcels; identifying low-temperature
heating of ruby, sapphire, aquamarine, Imperial topaz,
spinel and tanzanite; detecting Be-diffusion treatment
in parcels of melee-sized corundum; quantifying
clarity treatment in emerald; and detecting irradiation-related colour treatment of topaz, tourmaline,
morganite, etc. For diamonds, the challenges include:
detecting synthetics in melee-sized parcels of coloured
diamonds; identifying HPHT treatment in colourless,
Figure 1: Participants at the 5th National Conference of Gemmology gather in the lecture hall of the Department of Earth
Sciences at Sapienza University of Rome. This image was taken during the round-table discussion at the end of the conference.
Photo by B. M. Laurs.
CONFERENCES
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 719
Figure 2: A portion of the fine
gemstones exhibited during the
conference by gem cutter Luigi
Mariani are shown here.
Photo by B. M. Laurs.
pink and blue type IIa and IIb stones; and identifying
irradiation-related colour treatments, particularly for
green to greenish blue diamonds. He also mentioned
that country-of-origin determination is problematic
for coloured stones (particularly blue sapphire) and is
impossible for diamond. Dr Loredana Prosperi (Italian
Gemological Institute, Milan, Italy) chronicled gemmological developments seen by laboratories over the past
35 years. She described how gemmologists initially
had only a few simple tools that were used to deal with
relatively straightforward identification problems, but
as time went on the challenges became more complicated and so did the technology needed to address
them. She ended by questioning the role of gemmologists in the future as artificial intelligence becomes
more widespread in its application to gem analysis.
This author reviewed important gemmological developments of the past decade, including: progress in the
growth and characterisation of synthetic diamonds;
the proliferation of diamond verification devices for
the screening and detection of these synthetics (and
simulants); age dating of inclusions to assist with the
geographic origin determination of sapphire; research
on the unstable colouration (photochromism) of
pink, padparadscha, orange and yellow sapphires;
detection of low-temperature heat treatment of ruby
and sapphire; progress on the geographic origin determination of ruby, blue sapphire, emerald, Cu-bearing
tourmaline and alexandrite; and refinements in instrumentation and analytical techniques (especially
portable Raman and EDXRF spectroscopy).
Dr Emmanuel Fritsch (University of Nantes,
France) compared two types of hollow inclusions
in gems. The first, dissolved dislocations, form in a
variety of gems and result from preferential chemical
etching along defects such as edge and screw dislocations, resulting in surface-reaching, tapered, straight or
curved hollow tubes that commonly have a polygonal
cross-section. The second, rose channels, form in
diamond, corundum and calcite, and occur at the
intersection of twin lamellae where the migration of
vacancies results in straight, hollow channels with a
constant lozenge-shaped cross-section.
Diamonds were the topic of three presentations.
Sergio Sorrentino (E-motion Diamond, Marcianise,
Italy) looked at various aspects of the diamond trade,
particularly marketing and sustainability issues and
the increasing availability of synthetics. He emphasised that in order to maintain consumer confidence,
transparency is particularly critical when dealing with
synthetic diamonds—such as explaining their much
lower value and difficulty in reselling them as compared
to natural diamonds. Dr Fabrizio Nestola (University of
Padova, Italy) examined the depth at which superdeep
diamonds form. The most abundant inclusion in these
diamonds is ‘ferropericlase’ (or ‘magnesiowüstite’),
a variety of periclase with the formula (Mg,Fe)O. He
reviewed the use of this inclusion to determine the
depth of cogenetic diamond crystallisation, and also
examined the enigmatic occurrence of Fe-rich periclase
CONFERENCES
720 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
inclusions in these diamonds. Giulia Marras (with Dr
Vincenzo Stagno from Sapienza University of Rome)
discussed recent research on diamond inclusions using
multiple advanced techniques, and also covered current
growth techniques for synthetic diamonds, including
fluid-driven diamond synthesis in a rotating multianvil press.
Coloured stones were the topic of several presentations. Dr Federico Pezzotta (Mozambique Mining,
Milan, Italy) examined the geology, mining and heat
treatment of Cu-bearing tourmaline from Mavuco,
Mozambique. An average of 500 tonnes of material
are processed daily from this residual deposit, yielding
around 200–300 g of coloured tourmaline, of which
approximately 100 g are Cu bearing. The largest cut
stone produced in 2022 weighed 49 ct (Figure 3). Dr
Alessandra Altieri (Sapienza University of Rome)
reviewed the causes of colour in tourmaline, and then
explored the genesis of colour zoning in gem crystals
from Italy (Elba Island) and Mozambique (Mavuco). The
dark-coloured termination on a tourmaline from Elba
Island was found to be caused by Fe2+ that was derived
from the leaching of biotite in the outer zone of the
pegmatite, whereas the ‘leek-green’ (actually greenish
yellow) colouration of a sample from another pegmatite
on Elba Island was due to Mn2+–Ti4+ intervalence
charge transfer in the absence of iron. A multicoloured tourmaline fragment from Mavuco recorded
a complex history of enrichment in Mn2+, Mn3+,
Cu2+, Fe2+ and Fe3+ that showed an overall increase
in oxidising conditions during crystallisation. Dr Nicola
Precisvalle and colleagues (University of Ferrara, Italy)
studied Imperial topaz from Brazil and Pakistan, and
found that the most important trace element in this
type of topaz is Cr (associated with V). He noted
parallels with the nomenclature of Paraíba tourmaline (i.e. a colour variety regardless of locality). Dr
Isabella Pignatelli (University of Lorraine, Vandoeuvre-lès-Nancy cedex, France) described her research
on the blue/yellow dichroism of laurentthomasite (see
article on pp. 708–716 of this issue of The Journal), as
well as the possible presence of H2O in this nominally
anhydrous mineral. Dr Marco Campos-Venuti (Seville,
Spain) discussed the likely microbial origin of epigenetic dendritic inclusions in quartz (e.g. pyrite/limonite
aggregates, Mn-oxide colloform structures, ‘koi fish’
banded structures, etc.). The best evidence for their
microbial origin is provided by similarities in the
morphological structures of bacterial colonies.
Presentations on biogenic gem materials covered
pearls and coral. Piero De Stefano (Studio De Stefano
Gemmologi Associati, Rome) reviewed the current status
of the cultured pearl industry. He noted the following
trends: (1) production in Japan is way down, and the
price has increased by 40–50%, with 80% of these
cultured pearls going to China; (2) there is good availability of South Sea cultured pearls, but only in sizes up
to 18 mm, and prices are increasing; and (3) freshwater
cultured pearls are widely available, and there is large
demand for higher quality to compensate for the lack of
Japanese cultured pearls and the high cost of South Sea
products. Francesco Sequino (International Gemological Institute, Naples, Italy) described his studies of coral
treatments in order to differentiate between untreated
Figure 3: This image includes a
selection of the finest Cu-bearing
tourmaline gemstones from
Mavuco, Mozambique, that were
produced in 2022. The largest
stone weighs 49 ct. Photo ©
Elliott/Mozambique Mining LLC.
CONFERENCES
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 721
coral and material subjected to surface oiling/waxing,
filling of fractures or cavities with foreign substances,
and impregnating with coloured plastic or similar
substances. Useful tools included a hot point, a strong
UV lamp (to detect the presence and amount of fillers)
and Raman spectroscopy.
Instrumentation and analytical techniques were
profiled in three presentations. Dr Gioacchino
Tempesta (with co-author Dr Giovanna Agrosì, both
of the University of Bari Aldo Moro, Italy) reviewed
the application in gemmology of portable laser-induced
breakdown spectroscopy (LIBS) and Raman spectroscopy. LIBS is a qualitative (rather than quantitative)
chemical analysis technique that requires statistical
methods or artificial intelligence to be employed in data
processing in order to identify a sample’s mineral group,
whereas Raman spectroscopy is used in conjunction
with well-established databases (e.g. https://rruff.info)
for identification of specific minerals and is capable
of differentiating between polymorphs. Dr Danilo
Bersani (University of Parma, Italy) performed Raman
characterisation of zoisite and other sorosilicates. He
found that samples of yellow zoisite showed the same
Raman features regardless of locality (Tanzania and
the Alps), consistent with a lack of V. He also used
Raman spectroscopy to distinguish between different
members of the epidote group and measure the composition of specimens in the epidote-clinozoisite series.
Dr Gabriele Giuli (University of Camerino, Italy) and
colleagues reported the results of EPR and XAS spectroscopy to investigate the cause of colour in tanzanite.
They found that the main chromophores are V3+ and
Fe3+, but that no simple mechanism is able to explain
tanzanite’s violetish blue colouration.
The study of gems from antiquity and in cultural
heritage objects was the focus of three presentations.
Flavio Butini (Istituto Gemmologico Nazionale, Rome)
examined 43 engraved cabochons of ‘prase’ (Cr-bearing
chalcedony). Gemmological and EDXRF chemical
characterisation showed a high degree of homogeneity
for all of these samples, and also some clear differences
from ‘modern’ Cr-bearing chalcedony. This suggests a
single source for archaeological Cr-bearing chalcedony.
Currently known sources of this gem material include
Australia, Zimbabwe, Bolivia, Tanzania and Turkey,
but Pliny also mentioned Cyprus (now exhausted). Dr
Maura Fugazzotto and colleagues (University of Catania,
Italy) described recent research on gemstones in historical liturgical ornaments in Sicily using portable EDXRF
and Raman spectroscopy. The objects were found to
contain emerald, ruby, diamond, amethyst, rock crystal,
citrine, garnet, spinel and artificial glass. It is likely that
stones lost or removed during past handling and cleaning
of the objects were replaced by substitutes that were
different from the original materials (e.g. rock crystal
for diamond). Marco Torelli (Masterstones Gemmological Analysis Center, Rome) examined and photographed
an unusual ring owned by Pope Leo XII (who served in
1823–1829), which contains an approximately 2 ct ‘green
transmitter’ diamond surrounded by 25 ‘rubies’ (two of
which proved to be red spinel) that were mounted on
a slab of malachite. To photograph the ring, he used
focus stacking to improve the depth of field, and then
he processed the photos into a three-dimensional image
that could be rotated by a viewer in the metaverse.
There was one presentation related to jewellery
manufacturing, in which Rocco Gay delivered a talk for
Alessia Crivelli (Gruppo Aziende Orafe di Confindustria
Alessandria, Italy) on the Mani Intelligenti Foundation,
which seeks to make the small municipality of Valenza
attractive for the training and employment of young
goldsmiths.
Towards the end of the conference was a session
titled ‘Speed Presentations’ that featured four-minute
talks on a variety of subjects by eight speakers:
Antonio Angellotti (mineral inclusions in superdeep
diamonds from Juina, Brazil), Sara Monico (synchrotron X-ray powder diffraction of Aquaprase chalcedony),
Marco Palumbo (archaeological glasses from Roman
antiquity), Lorenzo Pasetti (Raman spectroscopy
of tourmaline gemstones), Chiemi Sasajima (new
developments pertaining to Japanese coral), Flavio
Butini for Rose Marie Scappin (three-dimensional
elastomeric measurements of glyptic gems) and
Marilisa Yolanda Spironello (Sicilian coral in fifteenthto sixteenth-century masterworks). Most of these speakers
also presented their research in a poster session during
the conference.
The conference closed with a round-table discussion
coordinated by Dr Eugenio Scandale (Accademia
Pugliese delle Scienze, Bari) and moderated by Dr
Giovanni Andreozzi, which partially focused on
answering the question, ‘What is a gem?’ Although
there is an accepted definition by the International
Mineralogical Association (IMA) for what constitutes
a mineral (a solid chemical substance formed as a result
of geological processes), this is not the case for a gem.
Based on the feedback obtained during the discussion,
the group plans to submit a proposed definition of a
gem to the IMA.
Brendan M. Laurs fga
GEM-A NOTICES
722 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Gem-A Notices
MESSAGE FROM GEM-A CEO ALAN HART
Welcome to this issue of
The Journal of Gemmology.
This summer, Gem-A’s
headquarters has been
buzzing with activities
and projects, which we
will be presenting in the
coming months, including
a brand-new website and
online Member’s area. In the meantime, as we release
the results from the June 2023 exams, we are also
thrilled to welcome our new students to Ely Place—
and our distance-learning students online—for the
new term starting this autumn. Later in October we
will commence our membership renewal process for
the year 2024. More information on how to renew your
membership will be provided in due course.
Looking further ahead, I am thrilled to announce
that the Gem-A Conference will be held in London
this autumn on Sunday 5 November. Registration is
now open for the conference and gala dinner, and I
personally look forward to offering a warm welcome
to many of our members, colleagues and partners. We
have an excellent line-up of six international speakers
who will deliver sessions on a wide range of gemmological and related topics.
I would like to extend my sincerest thanks once
again for your ongoing support. I hope you enjoy this
issue of The Journal, and I look forward to seeing
many of you again soon.
REGISTER NOW FOR THE GEM-A CONFERENCE
The Gem-A Conference will make an in-person
return on Sunday 5 November at etc.venues
County Hall, which overlooks the River Thames
and the Houses of Parliament in London. This
year’s event will feature a very full day with six
expert speakers and will conclude with the muchanticipated Conference Dinner at the Tower of
London (including a private tour of the new crown
jewels exhibit), which will provide a fantastic
opportunity to network with other gemmologists
and jewellery professionals. Registrations for the
conference and gala dinner are now open. More
information and a link to register is available
at https://gem-a.com/event/conference-2023.
On Monday 6 November and Tuesday 7 November,
attendees will have the option to attend a series
of workshops and field trips to make the most of
their visit to London.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 723
GEM-A NOTICES
2023 ANNUAL GENERAL MEETING
This year, the Gem-A Annual General Meeting (AGM)
will be held on 18 October at 17:00 at Gem-A’s headquarters on Ely Place. To encourage participation from our
global Membership base, voting on the resolutions
will take place prior to the AGM using Civica Election
Services. More information on the voting platform and
access to the AGM documentation will be provided to
Members via our email newsletters.
GIFTS TO THE ASSOCIATION
Gem-A is most grateful to the following for their
generous donations that will support continued
research and teaching:
Gaye Haselden, United Kingdom, for a rough
specimen of white coral.
Roy Huddlestone, United Kingdom, for donating
his entire collection of Lennix synthetic emeralds,
which were the first synthetic emeralds to be
grown in London.
Michal Kosior, Poland, for 14 rough pieces of
Baltic amber and one specimen of Baltic amber
sitting on the matrix on which it was found.
Enzo Liverino, CIBJO, Italy, for an important
reference collection of different varieties of coral,
both rough and polished.
Iona Pettit, United Kingdom, for donating her
late husband’s (Brian Pettit, gemmologist and
jeweller) entire gemmology library of 78 books.
Mark Sandum, United Kingdom, for a 0.20
ct round-brilliant-cut diamond with a burned
surface resulting from overheating during
jewellery repair.
Sally Spencer, United Kingdom, for a copy of her
book, Jewellers’ Quick Reference Guide to Working
with Gemstones.
Solly Solomons, United Kingdom, for four faceted
fluorite specimens.
GEM-A GRADUATION AND PRESENTATION OF AWARDS
The Gem-A Graduation and Presentation of Awards
ceremony will be held at Goldsmiths’ Hall in London
on Monday 6 November. This important event will
celebrate the achievements of our most recent graduating class, including special awards and prize winners.
Goldsmiths’ Hall, positioned at the junction of Foster
Lane and Gresham Street, opened in 1835 and is one
of London’s hidden treasures. The Livery Hall is an
awe-inspiring space and a magnificently proportioned
room with Corinthian columns and a richly moulded
ceiling decorated with gold leaf.
OBITUARY
Erik Schoonhoven, Amsterdam, The Netherlands,
passed away on 10 August 2023. He was a cultural and
literary historian who authored and reviewed articles
for The Journal.
LEARNING OPPORTUNITIES
724 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
Learning Opportunities
CONFERENCES AND SEMINARS
CIBJO Congress 2023
3–5 October 2023
Jaipur, India
https://www.cibjo.org/congress2023
17th International Conference on Applied
Mineralogy and Minerals (ICAMM 2023)
9–10 October 2023
New York, New York, USA
https://waset.org/applied-mineralogy-andminerals-conference-in-october-2023-in-new-york
Theme of interest: Industrial Minerals, Gems, Ores,
and Mineral Exploration
International Society of Appraisers 2023
Gems & Jewelry Symposium
13 October 2023
Online
https://www.isa-appraisers.org/courses/course/1513
Geological Society of America Annual Meeting
(GSA Connects 2023)
15–18 October 2023
Pittsburgh, Pennsylvania, USA
https://community.geosociety.org/gsa2023/home
Session of interest: Gemological Research in the 21st
Century—Gem Minerals and Localities
65th Anniversary Canadian Gemmological
Association (CGA) Gem Conference
20–22 October 2023
Vancouver, British Columbia, Canada
https://canadiangemmological.com/
2023-cga-conference-2
2023 Canadian Jewellers Association Industry
Summit
23 October 2023
Vancouver, British Columbia, Canada
https://canadianjewellers.com/
events/2023-cja-industry-summit
37th International Gemmological Conference
23–27 October 2023
Tokyo, Japan
https://www.igc-gemmology.org/igc-2023
Note: There will be a pre-conference jadeite excursion
and a post-conference pearl excursion.
Gem-A Conference
5 November 2023
London
https://gem-a.com/event/conference-2023
Note: Workshops and field trips (and a graduation
ceremony for Gem-A students) will take place on 6
November, and additional workshops will be held on
7 November.
GemGenève
2–5 November 2023
Geneva, Switzerland
https://gemgeneve.com
Note: Includes a seminar programme
New Mexico Mineral Symposium
10–12 November 2023
Socorro, New Mexico, USA
https://geoinfo.nmt.edu/museum/nmms/home.cfml
24th Federation for European Education in
Gemmology (FEEG) Symposium
13 January 2024
Barcelona, Spain
http://www.feeg-education.com/symposium
NAJA 61st Winter Education Conference
28–29 January 2024
Tucson, Arizona, USA
https://najaappraisers.com/event/61st-annualaceit-winter-education-conference
AGTA GemFair Tucson
30 January–4 February 2024
Tucson, Arizona, USA
https://agta.org/agta-gem-fair-tucson
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 725
LEARNING OPPORTUNITIES
Accredited Gemologists Association (AGA)
Tucson Conference
31 January 2024
Tucson, Arizona, USA
https://accreditedgemologists.org
Tucson Gem and Mineral Show
8–11 February 2024
Tucson, Arizona, USA
https://www.tgms.org/show
Note: The theme of the seminar programme is
‘Pegmatites: Crystals Big & Beautiful’.
Inhorgenta Munich
16–19 February 2024
Munich, Germany
https://inhorgenta.com/en
Note: Includes a seminar programme
Hasselt Diamond Workshop 2024 (SBDD XXVIII)
28 February–1 March 2024
Hasselt, Belgium
https://www.uhasselt.be/SBDD#anch-bce-sbdd-xxviii
Independent Jewelers Organization (IJO)
Conference
9–12 March 2024
Dallas, Texas, USA
https://www.ijo.com/events/conferences
MJSA Expo
10–12 March 2024
New York, New York, USA
https://www.mjsa.org/events/mjsa-expo
American Gem Society Conclave
15–17 April 2024
Austin, Texas, USA
https://www.americangemsociety.org/conclave-2024
Jewellery & Gem ASEAN Bangkok
1–4 May 2024
Bangkok, Thailand
https://aseanbangkok.exhibitions.jewellerynet.com
Note: Includes a seminar programme
Scottish Gemmological Association Conference
3–6 May 2024
Location TBA
https://www.scottishgemmology.org/conference-2023
7th Mediterranean Gem and Jewellery Conference
7–11 May 2024
Cavalese, Italy and Piran, Slovenia
https://www.gemconference.com
Note: Workshops will take place 7–9 May in Italy and
the conference will occur on 11 May in Slovenia. Preand post-conference tours are also available.
Gem-A Workshops and Courses
Gem-A, London
https://gem-a.com/education
Diplôme Universitaire de Gemmologie
(DUG; University Diploma in Gemmology)
25 March–3 June 2024
https://sciences-techniques.univ-nantes.fr/
formations/du-gemmologie
Note: The course will be taught in English at the
University of Nantes in France. An information
booklet in English can be downloaded at https://
tinyurl.com/mr3b4639.
Gemstone Safari to Tanzania
10–27 January 2024 and 3–20 July 2024
https://www.free-form.ch/tanzania/gemstonesafari.html
OTHER EDUCATIONAL
OPPORTUNITIES
Lectures with The Society of Jewellery Historians
Society of Antiquaries of London, Burlington House
https://www.societyofjewelleryhistorians.ac.uk/
current_lectures (lists lectures up to November 2024)
• Cordelia Donohue—New Research on Tuareg
Jewellery
and
Kathleen Walker-Meikle—Pet Bling: Jewelled
Animal Accessories in the Late Medieval and Early
Modern Period
24 October 2023
• John Benjamin—Jewellery from Anglesey Abbey
28 November 2023
• Sarah Laurenson—For a Banquet of Vampires:
Scottish Stones in Jewellery
23 January 2024
726 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
NEW MEDIA
New Media
Amber Art: A Journey Between
Science and Beauty
By Enrico Bonino, 2022. Self-published, https://enricobonino.eu/paleontology-publications, 300 pages, illus.,
ISBN 978-2960243611. EUR75.00 hardcover.
There is something magical about life forms
captured in amber or other types of fossilised
resin found around the globe. This fascination probably extends back to the origin of
humanity. Imagine a group of Neanderthals holding
pieces of amber up to the light and wondering how
such creatures could have entered this ‘stone’ without
breaking it into small pieces. While written accounts
of such early events may not exist, actual amber pieces
carved by our ancestors depicting animals and ancient
tools have been recovered.
Creatures in amber are so well preserved, one may
imagine they are still alive. This is what makes amber
inclusions so attractive to humans: a desire to live
forever. Just look at the attempts that have been made
to use cryonic procedures to preserve humans so they
could be brought back after death. Even the Egyptians
covered their mummies with cloth soaked in resin to
preserve them for a better afterlife.
Enrico Bonino is not the first to visualize amber art.
Combining the artistic and scientific aspects of amber
has been provided previously to English-language
readers with Rosa Hunger’s The Magic of Amber (1977)
and Jamey D. Allen’s The Mysteries of Amber (1990).
Polish readers have the book Tajemnice Bursztynem
(Amber Secrets) by Barbara Kosmowska-Ceranowicz
and Tomasze Konart (1989). In German is Günter and
Brigitte Krumbiegel’s 2001 book Faszination Bernstein
(Fascination Amber), and Chinese readers have Wonders
in Amber by Yi-Jen Huang (2008) and Amber—Lives
Through Time and Space by Fangyuan Xia et al. (2015).
The present work, Amber Art, has a similar theme
to the abovementioned books in that it shows how
artistic amber inclusions can be when examined with
the right lighting. While the table of contents arranges
the illustrations under several higher insect taxa, it is
their photographic presentation that is stressed as the
‘artistic’ part of the book. Amber inclusions, like human
art, retain their fascination and emotional suspense in
timeless fashion. A current example of such art is Ossip
Zadkine’s The Destroyed City, a statue of a damaged
figure arising from the rubble of Rotterdam after it was
bombed in the Second World War.
What makes Amber Art unique is the use of a special
camera to examine minute structures in the fossilised
resin, including those of entombed animals and plants—
aspects that only appear as specks to the general viewer.
These excellent photos of amber specimens are the result
of what the author calls ‘macro-extreme photography’,
with the camera attached to an extension tube and the
use of a microscopic objective. A wide range of lighting
was employed, and focus-stacking was done to obtain
a wide depth of field. Many of the photos in this book
display details that can be used scientifically to establish
new genera and species. All these features allow the
reader to see a microworld rarely available to the public.
These amazing advancements in the field of photomicrography reveal fine details previously rivalled only by
images obtained with a scanning electron microscope.
While a number of amber sources are listed in the
front of the book, most of the 333 specimens depicted
in Amber Art consist of Baltic amber. In fact, Baltic,
Dominican and Burmese amber specimens together
represent about 95% of the amber sources photographed.
Some viewers examining mid-Cretaceous Burmese amber
fossils may not realize that these species co-existed—
and possibly even had some physical contact—with
dinosaurs.
With its captivating photographs, Amber Art is a very
enjoyable book to read.
Dr George Poinar Jr
Oregon State University
Corvallis, Oregon, USA
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 727
NEW MEDIA
Nineteenth Annual Sinkankas
Symposium: San Diego County
Gems and Minerals
Ed. by Stuart Overlin, 2023. Pala International Inc., Fallbrook,
California, USA, https://sinkankas.dpidirect.com/category/
symposium-volumes, 97 pages, illus., ISBN 978-0991532070.
Approximately USD42.50 softcover or free PDF.*
* Editor’s note: Hardcopies of this and previous Sinkankas Symposium volumes are available annually in March through DPI Direct’s
print-on-demand service (https://sinkankas.dpidirect.com/category/root). The exact pricing depends on the cost of materials at
the time. Downloadable PDF files of this and the two previous Sinkankas Symposium volumes are freely available at https://
independent.academia.edu/SinkankasSymposium.
The Nineteenth Annual Sinkankas Symposium,
held in April 2023 at the Gemological Institute
of America (GIA) in Carlsbad, California, USA,
focused on the gems and minerals of San Diego
County, California. The event was co-hosted by GIA and
the Gemological Society of San Diego.
After a dedication, acknowledgements, and speaker
and author biographies, the abstracts of the symposium
presentations begin with ‘Tales from the Pala Chief
mine’ by Dr Raquel Alonzo-Perez of Harvard University,
followed by ‘Cutting the gems of San Diego County’ by
lapidary artist Meg Berry, ‘Eureka! My love affair with the
gems of Southern California’ by jewellery designer Paula
Crevoshay, ‘Using gems to illuminate art and science’ by
Dr Aaron Celestian of the Natural History Museum of Los
Angeles, ‘The microfeatures of gems and minerals from
San Diego County’ by GIA’s Nathan Renfro, ‘Tourmaline crystallography’ by William B. ‘Skip’ Simmons of
the Maine Mineral and Gem Museum, and ‘The causes
of color of the San Diego County gem minerals’ by Drs
George Rossman of the California Institute of Technology
and Aaron Palke of GIA.
Two previously published articles included in the
proceedings are ‘Spessartine garnet from Ramona, San
Diego County, California’ by Brendan M. Laurs and
Kimberly Knox (originally published in the Winter 2001
issue of Gems & Gemology) and ‘Pala pink and Mesa
Grande mauve’ by Ryan Bowling (from Rubellite—
Tourmaline Rouge, Lithographie Mineral Monograph No.
20, 2019). Also included is a previously unpublished
manuscript, ‘Himalaya mine: Mesa Grande, California’,
written in 1992 by Bill Larson and John Sinkankas.
Next is an ‘Image Gallery’ that includes 15 additional
illustrations. The volume concludes with a bibliography
compiled by GIA librarian Sheryl Elen.
Abstracts were not provided for four of the symposium
presentations: ‘San Diego County mines and minerals’
by mineral dealer Cal Graeber, ‘The great tourmalines
of the Pala mining district’ by Bill Larson of Pala International, ‘Himalaya mine treasures’ by Will Larson of
Pala International, and ‘Geology of San Diego County
pegmatites’ by Brendan M. Laurs, editor-in-chief of The
Journal of Gemmology.
The overall quality of this volume is very good. The paper
stock, printing and colour reproduction of the images—
lavishly distributed throughout the book—measure up to
the importance of the book’s theme. The wraparound cover,
with its many colourful images of fine San Diego County
gems and minerals shown over a geological map of the
Pala District, beckons you to open to the contents. The
abstracts and image gallery provide a wealth of diagrams,
charts, historical images and, of course, photos of minerals,
gems and jewellery. Bill Larson provided the specimens
shown in many of the images, including those on the cover.
The book contains photos by Jeff Scovil, Robert Weldon,
Orasa Weldon, Mia Dixon, Emily Lane, Paula Crevoshay
and others. Finally, the calibre of the speakers and authors
would be hard to beat for the topic.
I have little to criticise and much to recommend about
this unique book to mineral enthusiasts, gemmologists,
lapidaries, jewellers and anyone, like myself, who loves
the minerals, gems, geology and history of San Diego
County pegmatite mines, which began producing over
a century ago.
Michael T. Evans
Fallbrook Gem and Mineral Museum
Fallbrook, California, USA
728 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
NEW MEDIA
Pearl: Nature’s Perfect Gem
By Fiona Lindsay Shen, 2022. Reaktion Books, London,
https://reaktionbooks.co.uk/work/pearl, 287 pages, illus.,
ISBN 978-1789146219 or e-ISBN 978-1789146226. GBP25.00
hardcover or eBook.
earl: Nature’s Perfect Gem elaborates on subjects
regarding pearls that I had not seen in previous
books. Most publications I have read on pearls
focus heavily on the science, formation and
localities of pearls. This book discusses those subjects, but
it also details in an original way the sociological and historical impacts of pearls and the pearl trade on humanity and
global culture.
The first chapter, ‘The Oyster’s Autobiography’,
predictably begins with a discussion of pearl formation,
origins and traditional localities. Common myths and
fables involving pearls through history are reviewed,
along with references in popular literature. In the second
chapter, ‘Harvest’, the reader starts to see the human
cost of the pearl trade. Pearls have been harvested
from the Persian Gulf for most of human history, and
the lesson to be learned here is that very rarely were
those who dove for the pearls able to reap the rewards
of this dangerous activity. Descriptions of boats and
their crews that set out along the Gulf during pearling
season, even up to the 1960s, accompany accounts of
the cycle of financial ruin that followed the pearl divers.
Enslaved people from Africa—some kidnapped, others
born into slavery—were used during the pearl boom
of the nineteenth and early twentieth centuries. By
1929, roughly 20,000 enslaved divers worked the oyster
banks of the Persian Gulf each season. The chapter also
covers pearling activities in the Caribbean, Scotland and
northern Europe.
The next chapter, titled ‘Culturing Pearls, Capturing
Markets, Cultivating Brands’, details the creation,
marketing and branding of cultured pearls. The first
round pearls were cultured in Europe by none other than
Carl Linnaeus, the father of modern taxonomy. Unfortunately for him, his plan to cultivate pearls in Lapland
failed. Tavernier noted in the seventeenth century that
Japan did not especially value pearls, but subsequently in
the first part of the twentieth century Kokichi Mikimoto
was the first person instrumental to the successful
growth, branding and marketing of cultured pearls, not
just in Japan, but worldwide. Less known but just as
important were Tatsuhei Mise and Tokichi Nishikawa,
who developed advanced culturing techniques, some
of which are still used today for saltwater cultured
pearls. Japan retained an absolute hold on the cultured
pearl market until after World War II, when European
colonists started targeting the rich oyster beds of the
north-west Kimberley Coast of Australia, initially for
high-quality pearl shells, and subsequently for the
pearls. In what had become commonplace, colonists
conscripted Aboriginal free divers to collect the shells in
conditions comparable to slavery. After legislation was
passed in the 1870s to curb the worst of these abuses,
the colonists started importing indentured servants from
Southeast Asia, a practice that persisted into the 1970s.
This chapter also covers the environmental cost
of cultivating literally tonnes of cultured pearls, with
warnings as early as 1970 predicting the collapse of
the industry. In 1996 a massive die-off of saltwater
pearl-culturing molluscs began, and by year’s end
almost two-thirds of Japan’s oyster stock had died.
However, since the 1990s freshwater cultured pearl
farms in China have been booming, due in part to the
Hyriopsis cumingii mussel’s ability to tolerate water
pollution that saltwater oysters could not.
The chapter titled ‘The Seven Pearly Sins’ covers the
negative effects of pearls as they relate to lust, pride,
wrath, gluttony, envy, greed and sloth in the human
condition, with some surprising insights. The following
chapter, ‘And Seven Virtues’, covers the positive aspects
of pearls in terms of chastity, humility, patience, temperance, kindness, generosity and diligence. The fickleness
of human perception knows no bounds!
The book closes with ‘Embodied’, a discussion of
pearls in art and popular culture, both ancient and
modern. Painted jewellery boxes of Roman Egypt
(ca. first to third century ce) depict the upper classes
commonly wearing crotalia (bar-and-pendant earring
designs, also called castanet earrings, often with pearls),
which help historians understand the culture of the
time. The portraits were probably painted post-mortem
to help the subject ‘stay alive’ for eternity. Mantegna of
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 729
NEW MEDIA
Artificial Intelligence and
Spectroscopic Techniques for
Gemology Applications
Ed. by Ashutosh Kumar Shukla, 2022. IOP Publishing Ltd,
Glassfields, Bristol, 167 pages, illus., ISBN 978-0750339254
or e-ISBN 978-0750339278, https://doi.org/10.1088/978-0-
7503-3927-8. GBP120.00 hardcover or GBP99.00 eBook.
This book is a five-chapter work that explores
various analytical methods, including laserinduced breakdown spectroscopy (LIBS),
Raman spectroscopy, Fourier-transform
infrared spectroscopy (FTIR), optical tomography and
X-ray fluorescence (XRF) spectroscopy in the context of
gem analysis. Drawn in by the title, I anticipated a deep
dive into the application of artificial intelligence (AI)
within the realm of spectroscopic data, and its subsequent
utilisation for more accurate identification of gem
materials, treatments and geographical origins, all of
which are of significant relevance to contemporary
gemmological studies. However, if you are similarly
intrigued by the mention of ‘artificial intelligence’ in
the title, you may find the content of the book somewhat
disappointing. The term is essentially used in the
title alone, with most of the content having no direct
connection to AI. The chapters primarily introduce the
respective analytical techniques and illustrate examples
of their applications in gemmology. The closest part
to AI is perhaps chapter 3.9 (‘Application of machine
learning algorithm to gemstone classification’), yet the
discussion remains largely theoretical, lacks details and
does not offer concrete examples.
Chapter 1 opens with a discussion of LIBS used for
gem analysis, with a considerable portion focusing
on the theory behind the technique and the formula
deduction for calibration-free LIBS. The method is
particularly appealing for being quick and cost-effective while leaving minimal markings on samples. Section
1.3 includes some background from the literature, from
the detection of Be diffusion-treated corundum in the
early 2000s to the classification of beryl of various
colours. The authors then provide additional examples
Mantua (who had a reputation as a gem expert as well as
an artist) was the first to depict in his ca. 1460 painting
The Adoration of the Magi an independent (rather than
‘owned’) man of colour, Balthazar, as an ambassador
wearing his own pearls. Vermeer’s 1665 painting Girl
with a Pearl Earring demonstrates how such a perfect
illustration of a pearl was achieved by using no less than
four different types of lead-white pigment to produce
convincing ‘pearliness’ on a two-dimensional surface.
Depictions of pearls in art were not confined to
northern European art. Mughal miniatures were often
painted in opaque watercolours with organic and
inorganic chemical bases, and lead white again was
used to depict pearls. Some of the best miniatures use
real seed pearls and gemstones instead of paint. In both
Chinese and Japanese cultures, mother-of-pearl was
often employed as wafer-thin pieces to depict scenes
such as plum blossoms in moonlight. A lovely platter
depicts, in mother-of-pearl, two dragons chasing the
mythical ‘Flaming Pearl’.
The ‘Embodied’ chapter ends with a description of
how, in modern times, Catherine Opie photographed
items belonging to the late actress Elizabeth Taylor.
The resulting book, 700 Nimes Road, has some images
of Taylor’s fabled jewellery collection, including the
famous La Peregrina pearl. An historic pearl with a hazy
past, Opie’s artistic image of La Peregrina is purposefully blurred to convey the idea of a jewel rather than
a photograph.
I highly recommend this book to anyone interested in
pearls, if only for its unique perspective on how pearls
and the pearl industry have influenced both ancient and
modern culture. This book is well researched, and offers
copious chapter notes and an excellent bibliography. It is
also richly illustrated with historical paintings, modern
photos and other images that enhance the text.
Jo Ellen Cole
Cole Appraisal Services
Los Angeles, California, USA
730 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
NEW MEDIA
from the literature that use more advanced LIBS-based
techniques, such as calibration-free LIBS, double-pulse
LIBS and nanoparticle-enhanced LIBS. In terms of multivariate statistical analysis of the LIBS spectra, the authors
briefly introduce research by Kochelek et al. (2015)
using partial least-squares regression to reach a high
accuracy (>95%) in the geographical origin classification of ruby and sapphire. A study by Eum et al. (2018)
using a hierarchical support vector machine approach
to combined Raman and LIBS data also showed high
accuracy (>90%).
Chapter 2 covers gem analysis using Raman spectroscopy. After introducing the technique, the authors
compare benchtop and mobile instrumentation. The
latter extends the capability of the Raman technique
outside of the lab environment, such as in geological
fieldwork or on-site in museums. In the following section,
the authors showcase some studies on various gems and
jewelled artefacts, including garnet, jade, beryl, corundum,
glass, pearl, coral and simulants. A short section also
covers photoluminescence analysis using a Raman system.
This technique can provide complementary information
that is measured at the same time as Raman analysis.
Chapter 3 begins with an introduction to the concept
of FTIR spectroscopy. It provides not only a brief theoretical background but also an extended comparison of
different sampling techniques for the FTIR analysis of
gems. Then the authors describe how FTIR spectroscopy
can help the identification of various gem materials.
Starting with diamond, the chapter covers type classification, characterisation of synthetic and treated diamonds,
and the detection of simulants. A similar approach is
taken for other gems, such as corundum, emerald,
quartz, jade and turquoise. In discussing the origin determination of emerald, the authors stress the importance of
combining complementary analytical techniques. Section
3.9 describes a path for gem classification via machine
learning. However, this section feels somewhat disjointed
from the previous ones, as it consists of many techniques
other than FTIR. While the authors’ perspectives may
be trendy, in my view many of the methods mentioned
seem oversimplified compared to the realities of their
implementation. The absence of any tangible examples
lends the section a promotional tone, and it comes across
as somewhat unconvincing. Nevertheless, in general,
this chapter provides useful ‘fingerprint’ information
for gem applications.
Chapter 4 describes the use of optical tomography for
ruby clarity grading. However, the authors wrote this
section in a way I found hard to understand. Unlike the
better-known X-ray tomography, this technique uses a
red laser diode as an emission source and a CCD plate
as a detector. It then employs an image-reconstruction
process, but there is no three-dimensional tomogram
of the ruby shown after the calculation, which I found
puzzling. For X-ray tomography to work properly,
an X-ray penetrates the sample and largely keeps its
direction before reaching the detector. In optical tomography, it is necessary to consider the refraction of light
in the gemstone, but there is no mention of how this
is handled. In addition, the authors indicate that ‘Due
to the overly complex mathematical model, light
scattering and the diffraction effect were elected to be
disregarded in this study’s calculations’ (p. 4-4), which
sounds debatable. Moreover, the last two sentences of
the chapter’s conclusion (p. 4-13) may not be true in
many cases: ‘A ruby stone with better clarity is considerably more expensive in comparison to a ruby stone with
lower clarity. In other words, a ruby stone with a lower
refractive index indicates that it commands a higher
price compared to a ruby stone with a higher refractive
index.’ Readers would be better off not assuming these
to be universal truths.
Chapter 5 introduces trace-element analysis of gems
using XRF. It begins with some basic principles of the
technique, followed by a comparison of advantages over
other trace-element techniques. A large portion of the
chapter then presents some case studies in which XRF
was potentially helpful. These examples include garnet
(distinguishing tsavorite from demantoid), tourmaline
(determining the colouring agents in blue and ‘watermelon’ tourmalines), pearl (separating freshwater from
saltwater origin, and colour-treatment detection) and
ruby (fluorescence intensity variations related to Cr:Fe
ratio). The authors further discuss ‘big data applications in gemology’ in section 5.4, with two examples of
geographical origin determination for ruby and spinel.
The chapter illustrates a bivariate scatter plot (Figure
5.22) and score plot (Figure 5.29) using linear discrimination analysis to distinguish a few countries of origin
for ruby and spinel. Unfortunately, the term ‘big data’
is not adequately supported by the content, and it is not
convincing that the authors consider an XRF spectroscopy dataset, which can be handled with an Excel
spreadsheet, as ‘big’.
In conclusion, this book provides some useful information about the analysis of gem materials using
various spectroscopic techniques. Each chapter begins
with an introduction to the technique, and most chapters
offer actual examples. However, it would have been
beneficial if the book had dedicated a section to ultraviolet-visible-near infrared spectroscopy, a crucial
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 731
NEW MEDIA
Other Book Titles
CULTURAL HERITAGE
The Bone and Ivory Objects from Gordion
By Phoebe A. Sheftel, 2023. University of Pennsylvania Press, Philadelphia, Pennsylvania, USA,
584 pages, ISBN 978-1949057171 or e-ISBN
978-1949057188. USD120.00 hardcover or eBook.
The Gordion Excavations, 1950–1973: Final Reports
Volume II—The Lesser Phrygian Tumuli Part 2:
The Cremations
By Ellen L. Kohler and Elspeth R. M. Dusinberre,
2023. University of Pennsylvania Press, Philadelphia,
Pennsylvania, USA, 792 pages, ISBN 978-1949057157
or e-ISBN 978-1949057164. USD120.00 hardcover
or eBook.
The Magnificent Kunlun Jade: The Songzhutang
Collection of Ming and Qing Jade
By Thomas Fok, 2023. CA Book Publishing, Hong
Kong, 190 pages, ISBN 978-9887608936. HKD800.00
hardcover.
INSTRUMENTATION
Chemometrics and Numerical Methods in LIBS
By Vincenzo Palleschi, 2023. John Wiley & Sons,
Hoboken, New Jersey, USA, xviii + 360 pages,
ISBN 978-1119759584 or e-ISBN 978-1119759614,
https://doi.org/10.1002/9781119759614. USD165.00
hardcover or eBook.
Laser Induced Breakdown Spectroscopy (LIBS):
Concepts, Instrumentation, Data Analysis and
Applications
Ed. by Vivek K. Singh, Durgesh Kumar Tripathi,
Yoshihiro Deguchi and Zhenzhen Wang, 2023.
John Wiley & Sons, Hoboken, New Jersey,
USA, 1,008 pages, ISBN 978-1119758402 or
e-ISBN 978-1119758426, https://doi.org/10.1002/
9781119758396. USD395.00 hardcover or eBook
(two-volume set).
JEWELLERY HISTORY
The Material Landscapes of Scotland’s Jewellery
Craft, 1780–1914
By Sarah Laurenson, 2023. Bloomsbury Publishing,
London, 272 pages, ISBN 978-1501358005, e-ISBN
978-1501357985 (PDF) or 978-1501357992 (ePub).
GBP90.00 hardcover or GBP81.00 eBook.
Speculum Lapidum: A Renaissance Treatise on the
Healing Properties of Gemstones
By Camillo Leonardi (transl. with an introduction by
Liliana Leopardi), 2023. Penn State University Press,
University Park, Pennsylvania, USA, 240 pages, ISBN
978-0271095394. USD39.95 hardcover.
JEWELLERY AND OBJETS D’ART
Jakob Bengel, Oberstein: From Art Industry
to Jewellery Design
Ed. by Jakob Bengel-Stiftung, 2023. Arnoldsche Art
Publishers, Stuttgart, Germany, 152 pages, ISBN
978-3897906952 (in English and German). EUR28.00
hardcover.
Liber Amicorum in Honour of Diana Scarisbrick:
A Life in Jewels
By Beatriz Chadour-Sampson, Sandra Hindman and
Carla van de Puttelaar, 2022. Ad Ilissvm, London, 280
pages, ISBN 978-1915401021. GBP35.00 hardcover.
Therese Hilbert—RED: 1966–2020 Jewelry
By Heike Endter, Warwick Freeman, Petra Hölscher,
Otto Künzli, Ellen Maurer Zilioli, Pravu Mazumdar
and Angelika Nollert, 2023. Arnoldsche Art
spectroscopic tool for coloured-stone testing. Secondly,
the book clearly lacks AI-related content, while certain
buzzwords related to machine learning and big data are
overused. Thus, the notion of AI as a ‘silver bullet’ to
aid gemmologists in gem testing or address challenges in
gemmological research may be premature. I am awaiting
a contribution that can demonstrate the power of AI to
assist gemmological work. Regrettably, this book isn’t it.
Dr Hao A. O. Wang fga
Swiss Gemmological Institute SSEF
Basel, Switzerland
732 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
NEW MEDIA
Publishers, Stuttgart, Germany, 360 pages,
ISBN 978-3897906235 (in English and German).
EUR38.00 hardcover.
A Touch of Gold: The Reminiscences of Geoffrey Munn
By Geoffrey Munn, 2023. ACC Art Books, Woodbridge,
Suffolk, 208 pages, ISBN 978-1788841979. GBP25.00
hardcover.
Walid Akkad: Bestiaire
By Michael Jakob, 2023. Silvana Editoriale, Milan, Italy,
96 pages, ISBN 978-8836653164. EUR35.00 hardcover.
Windows at Tiffany & Co.
By Christopher Young, 2023. Assouline Publishing,
New York, New York, USA, 148 pages, ISBN
978-1649802224. USD85.00 hardcover.
MISCELLANEOUS
The Chatham Legacy: An American Story
By Thomas H. Chatham, 2023.
Thomas H. Chatham, Half Moon Bay,
California, 219 pages, ISBN 979-8987916100.
USD90.00 hardcover.
King of Diamonds: Harry Winston—The Definitive
Biography of an American Icon
By Ronald Winston & William Stadiem, 2023.
Skyhorse Publishing Inc., New York, New York,
USA, 336 pages, ISBN 978-1510775602 or ASIN
B0B6WKFL1M. USD28.99 hardcover or USD17.99
Kindle edn.
PEARLS
The Story of the Pearl
By Caroline Young, 2023. OH! (Orange Hippo/
Welbeck Publishing Group), London, 160 pages, ISBN
978-1838611422. GBP14.99 hardcover or GBP7.99
eBook.
SOCIAL STUDIES
Under Pressure: Diamond Mining and Everyday
Life in Northern Canada
By Lindsay A. Bell, 2023. University of Toronto
Press, Toronto, Ontario, Canada, 188 pages, ISBN
978-1487548278 (hardcover), 978-1487548216
(softcover), e-ISBN 978-1487548872 (ePub) or
978-1487548575 (PDF). CAD75.00 hardcover,
CAD26.95 softcover or CAD21.95 eBook.
Find out more by contacting: [email protected]
Our FGA and DGA Members are located around the world –
join them by studying with Gem-A
Gem-A: over 110 years of experience
in gemmology education
At Gem-A HQ
London
Worldwide at
one of our ATCs
Online with
practical lab classes STUDY in your area
IN ONE
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WAYS
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 733
LITERATURE OF INTEREST
Literature of Interest
COLOURED STONES
Agates from Mesoproterozoic volcanics (Pasha–
Ladoga basin, NW Russia): Characteristics and
proposed origin. E.N. Svetova and S.A. Svetov,
Minerals, 13(1), 2022, article 62 (26 pp.),
https://doi.org/10.3390/min13010062.*
Amethyst, the national stone of Korea. B. Koo,
Wooshin Gem Lab Magazine, 10, 2023, 12–17,
https://tinyurl.com/mv5cjpdb.*
Atomic and microstructural origin of banded
colours in purple-blue variety of agate from Yozgat
Province, Turkey. R. Lorenzi, A. Zullino, V. Gagliardi,
L. Prosperi, A. Paleari and I. Adamo, Physics and
Chemistry of Minerals, 49(8), 2022, article 33 (8 pp.),
https://doi.org/10.1007/s00269-022-01208-3.*
Characteristics of channel-water in blue-green
beryl and its influence on colour. H. Wang, T. Shu,
J. Chen and Y. Guo, Crystals, 12(3), 2022, article 435
(13 pp.), https://doi.org/10.3390/cryst12030435.*
Chromatographic study of blue-violet tanzanite’s color appearance. L. Qiu, Y. Guo, B. Yuan,
Y.S. Su and Y.H. Qi, Science of Advanced Materials,
14(6), 2022, 1032–1040, https://doi.org/10.1166/
sam.2022.4288.
Cobalt spinel from Mahenge. J.G.G.L. Gem Information,
49, 2023, 8–9 (in Japanese with English abstract).
Color coordination of emerald on CIE color space
based on first-principles calculations. M. Novita,
R.M.D. Ujianti, F. Nurdyansyah, S. Supriyadi,
D. Marlina, R.A.S. Lestari, B. Walker, N.I. Binti
Mohd Razip et al., Optical Materials: X, 16, 2022,
article 100184 (9 pp.), https://doi.org/10.1016/j.
omx.2022.100184.*
Color effects of Cu nanoparticles in Cu-bearing
plagioclase feldspars. S. Jin, Z. Sun and A.C. Palke,
American Mineralogist, 107(12), 2022, 2188–2200,
https://doi.org/10.2138/am-2022-8325.
Colored Stones Unearthed: Gems formed in
metamorphic rocks. A.C. Palke and J.E. Shigley,
Gems & Gemology, 59(2), 2023, 232–241,
https://tinyurl.com/yxtb3u65.*
Combining rare earth element analysis and chemometric method to determine the geographical origin
of nephrite. Y. Su and M. Yang, Minerals, 12(11),
2022, article 1399 (14 pp.), https://doi.org/10.3390/
min12111399.*
The covariation of color and orange fluorescence
instabilities in yellow sapphires. Y. Yang, C. Wang,
C. Wang, X. Shen, K. Yin, T. Chen, A.H. Shen, T.J.
Algeo et al., Minerals, 13(5), 2023, article 663 (14
pp.), https://doi.org/10.3390/min13050663.*
Fascinating structures within slices from dark
tourmaline crystals. P. Rustemeyer, Rocks & Minerals,
98(5), 2023, 418–437, https://doi.org/10.1080/003575
29.2023.2213151.
Fire obsidian’s beguiling spectrum. R. Weldon
and N. Renfro, Gems & Gemology, 59(2), 2023,
260–266, https://www.gia.edu/gems-gemology/
summer-2023-in-the-spotlight.*
Gemmological and mineralogical characteristics of
light blue-green phosphophyllite from Bolivia.
X. Chen, J. Wang, Y. Chen and S. Gao, Journal of
Gems & Gemmology, 24(4), 2022, 18–25, https://
tinyurl.com/yc5p5z78 (in Chinese with English
abstract).*
Gemological characteristics of Lvwen stone and its
color genesis. Z. Liu, W. Wang, K. Yin, H. Hong, T.J.
Algeo, Z. Yin, Y. Pan, Z. Lu et al., Minerals, 12(12),
2022, article 1584 (14 pp.), https://doi.org/10.3390/
min12121584.*
Gemological and mineralogical studies of greenish
blue apatite in Madagascar. Z.Y. Zhang, B. Xu,
P.Y. Yuan and Z.X. Wang, Crystals, 12(8), 2022,
article 1067 (19 pp.), https://doi.org/10.3390/
cryst12081067.*
734 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
LITERATURE OF INTEREST
Gemological and spectral characteristics of
emeralds from Swat Valley, Pakistan. S. Cao, H. Dai,
C. Wang, L. Yu, R. Zuo, F. Wang and L. Guo, Spectroscopy and Spectral Analysis, 42(11), 2022, 3533–3540,
http://www.gpxygpfx.com/EN/Y2022/V42/I11/3533
(in Chinese with English abstract).*
Gemological and spectroscopic characteristics of
“Jedi” spinel from Man Sin, Myanmar. L. Zhao,
G. Li and L. Weng, Minerals, 12(11), 2022, article
1359 (13 pp.), https://doi.org/10.3390/min12111359.*
Gemstone inclusion study by 3D Raman-mapping
and high-resolution X-ray computed tomography:
The case of trapiche emerald from Swat, Pakistan.
Y. Gao, M. He, X. Li, M. Lin, X. Sun and Y. Zhang,
Crystals, 12(12), 2022, article 1829 (18 pp.),
https://doi.org/10.3390/cryst12121829.*
Gemstone occurrences and ancient circular impactscars: The gemmology tail wags the geology dog.
J.M. Saul, Australian Gemmologist, 28(3), 2023,
130–135.
Gota de aceite: Emerald’s secret attraction.
R. Ringsrud, Rivista Italiana de Gemmologia/Italian
Gemological Review, No. 16, 2023, 58–63.
Identification of the origin of bluish white nephrite
based on laser-induced breakdown spectroscopy
and artificial neural network model. P. Bao,
Q. Chen, A. Zhao and Y. Ren, Spectroscopy and
Spectral Analysis, 43(1), 2023, 25–30, http://www.
gpxygpfx.com/EN/Y2023/V43/I01/25 (in Chinese
with English abstract).*
The impact of Munsell neutral grey backgrounds
on tsavorite’s color and study on the evaluation
method of color gem cutting. Y. Ma and Y. Guo,
Applied Sciences, 13(3), 2023, article 1673 (14 pp.),
https://doi.org/10.3390/app13031673.*
Le métamorphisme hydrothermal : la genèse
des émeraudes [Hydrothermal metamorphism:
The genesis of emeralds]. M. Mahfoufi, Revue de
Gemmologie A.F.G., No. 220, 2023, 10–13 (in French).
Mineral component and genesis of high-grade
green jadeite jade from Guatemala. L. Wang,
H. Zhang, J. Liu, L. Wang, Q. Ouyang, D. Liu and
W. Liu, Journal of Gems & Gemmology, 24(5), 2022,
11–30, https://tinyurl.com/5n7cxkab (in Chinese with
English abstract).*
Minor elements and color causing role in spinel:
Multi-analytical approaches. T. Pluthametwisute,
B. Wanthanachaisaeng, C. Saiyasombat and
C. Sutthirat, Minerals, 12(8), 2022, article 928 (19
pp.), https://doi.org/10.3390/min12080928.*
New finds of cobalt-bearing spinel near Mahenge,
Tanzania. T. Stephan, U. Henn and S. Muller,
Australian Gemmologist, 28(3), 2023, 136–142.
Non-destructive study of Egyptian emeralds
preserved in the collection of the museum of the
Ecole des Mines. M. Nikopoulou, S. Karampelas,
E. Gaillou, U. Hennebois, F. Maouche, A. Herreweghe,
L. Papadopoulou, V. Melfos et al., Minerals, 13(2),
2023, article 158 (15 pp.), https://doi.org/10.3390/
min13020158.*
Opal pineapples from White Cliffs, New South
Wales, Australia. P. Carr, M. Southwood, B. Jones and
G. Dowton, Rocks & Minerals, 98(5), 2023, 404–417,
https://doi.org/10.1080/00357529.2023.2213150.
Optical properties of sulfur bearing sodalite.
S.K. Lee, Wooshin Gem Lab Magazine, 9, 2022, 2–5,
https://tinyurl.com/4nuyb7jh.*
Origin of blue-water jadeite jades from Myanmar
and Guatemala: Differentiation by non-destructive spectroscopic techniques. Y. Zhang and G. Shi,
Crystals, 12(10), 2022, article 1448 (16 pp.),
https://doi.org/10.3390/cryst12101448.*
Our friends the inclusions. The detective at
the party of inclusions. Fourteenth episode
[corundum]. L. Costantini and C. Russo, Rivista
Italiana de Gemmologia/Italian Gemological Review,
No. 16, 2023, 7–13.
Photomicrographies d’une opale d’Éthiopie
[Photomicrographs of an Ethiopian opal].
M. Bouvier, Revue de Gemmologie A.F.G., No. 219,
2023, 33 (in French).
Pink to purple sapphires from Ilakaka, Madagascar:
Insights to separate unheated from heated samples.
S. Karampelas, U. Hennebois, J.-Y. Mevellec, V.
Pardieu, A. Delaunay and E. Fritsch, Minerals, 13(5),
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 735
LITERATURE OF INTEREST
2023, article 704 (14 pp.), https://doi.org/10.3390/
min13050704.*
Purple chalcedony from Ethiopia. J.G.G.L. Gem
Information, 49, 2023, 1–2 (in Japanese with English
abstract).
Quantitative study on colour and spectral characteristics of Beihong agate. Y. Zhou, Z. Liu, Z. Zhao
and Y. Guo, Minerals, 12(6), 2022, article 1448 (16
pp.), https://doi.org/10.3390/min12060677.*
Quelques éclaircissements sur la labradorescence.
Partie 2 : Exemple des labradorites de Madagascar
[Some clarifications on labradorescence. Part 2:
Example of labradorites from Madagascar].
M. Cagnon-Trouche, J.-C. Boulliard, I. Estève and
P. Giura, Revue de Gemmologie A.F.G., No. 219, 2023,
5–14 (in French with English abstract).
Raman analysis of the characteristics of chrysoberyl containing an excessive amount of iron.
S. Noh, Wooshin Gem Lab Magazine, 9, 2022, 12–15,
https://tinyurl.com/4nuyb7jh.*
Raman spectroscopic study on inclusion in
sapphire from Azad-Kashmir. T. Huang, Y. Gao,
X. Sun and Q. Han, Journal of Gems & Gemmology,
24(5), 2022, 101–108, https://tinyurl.com/3mvfb7xh
(in Chinese with English abstract).*
Rapid screening of a photochromic padparadscha-like sapphire using absorption spectroscopy.
Z. Wang, T.H. Tsai and H. Takahashi, Applied
Optics, 61(27), 2022, article 8108 (7 pp.),
https://doi.org/10.1364/ao.460718.*
A research of emeralds from Panjshir Valley,
Afghanistan. Q. Chen, P. Bao, Y. Li, A.H. Shen,
R. Gao, Y. Bai, X. Gong and X. Liu, Minerals, 13(1),
2022, article 63 (22 pp.), https://doi.org/10.3390/
min13010063.*
Reversible photochromic effect in natural gemstone
sapphires. T.H. Tsai, Z. Wang and H. Takahashi,
Optics Letters, 47(22), 2022, article 5805 (4 pp.),
https://doi.org/10.1364/ol.474838.*
Silicate gems. M. Mauthner, Rocks & Minerals, 98(1),
2023, 28–43, https://doi.org/10.1080/00357529.2023.
2126698.
Spectroscopic study on the species and color
differences of gem-quality red garnets from Malawi.
M. Li and K.S.V. Krishna Rao, Journal of Spectroscopy,
2022, 2022, article 1638042 (9 pp.), https://doi.org/
10.1155/2022/1638042.*
Spectroscopy characteristics of emerald from Swat
Valley, Pakistan. P. Bao, Q. Chen, Y. Wu, X. Li and
A. Zhao, Spectroscopy and Spectral Analysis, 43(1),
2023, 213–219, http://www.gpxygpfx.com/EN/abstract/
abstract13115.shtml (in Chinese with English abstract).*
The story behind the Smithsonian’s newest gem: The
exquisite Lion of Merelani. J. Tamisiea, Smithsonian
Magazine, 20 April 2023, https://tinyurl.com/yaffkz6h.*
The structural origin of the efficient photochromism in natural minerals. P. Colinet, H. Byron,
S. Vuori, J.P. Lehtiö, P. Laukkanen, L. Van Goethem,
M. Lastusaari and T. Le Bahers, Proceedings of
the National Academy of Sciences, 119(23), 2022,
article e2202487119 (7 pp.), https://doi.org/10.1073/
pnas.2202487119.
Study on the chemical composition and spectroscopy characteristics of emeralds from Bahia mining
area, Brazil. J. Hua and J. Di, Journal of Gems &
Gemmology, 24(5), 2022, 109–117, https://tinyurl.
com/3hz4e9w8 (in Chinese with English abstract).*
Study on the color-influencing factors of blue iolite.
X. Liu and Y. Guo, Minerals, 12(11), 2022, article 1356
(10 pp.), https://doi.org/10.3390/min12111356.*
Study on fluorescence properties of green-blue
apatite. Q. Yan, Z. Liu and Y. Guo, Crystals, 12(6),
2022, article 866 (15 pp.), https://doi.org/10.3390/
cryst12060866.*
Study on the spectral characteristics and the colorchange effect of spinel. Z. Wang, X. Mao, Z. Yin,
C. Chen and T. Cheng, Spectroscopy and Spectral
Analysis, 42(11), 2022, 3541–3545, http://www.
gpxygpfx.com/EN/Y2022/V42/I11/3541 (in Chinese
with English abstract).*
Study on spectral characteristics of gem grade
cassiterite in Yunnan. R. Zhang, G. Yang and Y. Bai,
Superhard Material Engineering, 34(2), 2022, 58–62,
https://tinyurl.com/2p86p8uk (in Chinese with
English abstract).
736 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
LITERATURE OF INTEREST
Tenebrescent zircon. J.G.G.L. Gem Information, 49,
2023, 5–6 (in Japanese with English abstract).
True jades, false friends. G.L. Barnes, Tectonic
Archaeology. Archaeopress Publishing Ltd, Oxford,
2022, 338–372, https://doi.org/10.2307/j.ctv35n89zf.20.
Variation in gemological characteristics in
tsavorites with different tones from East Africa.
Y. Ma and Y. Guo, Crystals, 12(11), 2022, article 1677
(14 pp.), https://doi.org/10.3390/cryst12111677.*
Water characterization and structural attribution of
different colored opals. N. Li, Q. Guo, Q. Wang and
L. Liao, RSC Advances, 12(47), 2022, 30416–30425,
https://doi.org/10.1039/d2ra04197a.*
Zultanite: Trick or treat? N. Zolotukhina,
Gemmology Today, June 2023, 69–73, https://
tinyurl.com/8fnw3ktt.*
CULTURAL HERITAGE
The Amsterdam diamond ‘marketplace’ and the
Jewish experience. K. Hofmeester, Jewish Culture
and History, 24(1), 2023, 50–75, https://doi.org/
10.1080/1462169x.2022.2156189.
Escarboucles & dragons, lexicologie des gemmes
rouges [Carbuncles & dragons, lexicology of
red gems]. N. Zylberman, Revue de Gemmologie
A.F.G., No. 219, 2023, 27–32 (in French with English
abstract).
Les grenats dits « de Perpignan » [The so-called
‘Perpignan’ garnets]. M. Errera, I. Fordebras,
A. La Viose and A.-M. Moigne, Revue de Gemmologie
A.F.G., No. 219, 2023, 15–26 (in French with English
abstract).
A luxe for the ears. Roman earrings in Augusta
Emerita (Mérida) and the province of Lusitania.
N.B. Martín, in L.P. Pujol & J.P. González, Eds., De
Luxuria Propagata Romana Aetate – Roman Luxury in
Its Many Forms. Archaeopress Publishing Ltd, Oxford,
2023, 109–136, https://doi.org/10.2307/jj.1357306.12.
Un « miroir » préhispanique en obsidienne de
l’expédition géodésique sur l’équateur (1735–1743)
découvert dans les collections de minéralogie du
Muséum national d’Histoire naturelle
[A pre-Hispanic obsidian ‘mirror’ from the geodesic
expedition to the equator (1735–1743) discovered in
the mineralogy collections of the National Museum
of Natural History]. F. Gendron, Revue de Gemmologie A.F.G., No. 220, 2023, 14–17 (in French with
English abstract).
Pearls, beryls, and priestesses in the Latin West:
Pearls and gems as symbols of female power and
devotion, as well as impiety and irreverence.
A.S. Morales, in L.P. Pujol & J.P. González, Eds.,
De Luxuria Propagata Romana Aetate – Roman
Luxury in Its Many Forms. Archaeopress Publishing
Ltd, Oxford, 2023, 137–166, https://doi.org/10.2307/
jj.1357306.13.
Raman spectroscopic characteristic of red coral
artifact and its communication between China and
the West before the 19th century. T. Lin, Y. Yuan,
Y. Xu and Q. Liu, Journal of Gems & Gemmology,
24(6), 2022, 141–151, https://tinyurl.com/msc52v97
(in Chinese with English abstract).*
DIAMONDS
Botswana, le nouveau géant du diamant [Botswana,
the new diamond giant]. É. Gonthier and
M. Valentin, Revue de Gemmologie A.F.G., No. 220,
2023, 18–21 (in French with English abstract).
Crystallogenetic causes of the unique shape of the
Matryoshka diamond: The effect of capturing a
diamond inclusion of twin diamond crystals.
A.D. Pavlushin and D.V. Konogorova, Geochemistry
International, 61(3), 2023, 252–264, https://doi.
org/10.1134/s0016702923030102.
Electron probe microanalysis and microscopy of
polishing-exposed solid-phase mineral inclusions
in Fuxian kimberlite diamonds. D. Zhao, Minerals,
12(7), 2022, article 844 (36 pp.), https://doi.org/
10.3390/min12070844.*
From the lithosphere to the lower mantle: An
aqueous-rich metal-bearing growth environment to
form type IIb blue diamonds. L. Daver, H. Bureau,
É. Boulard, É. Gaillou, P. Cartigny, D.L. Pinti,
O. Belhadj, N. Guignot et al., Chemical Geology,
613, 2022, article 121163 (18 pp.), https://doi.
org/10.1016/j.chemgeo.2022.121163.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 737
LITERATURE OF INTEREST
Gemmological and spectroscopic characteristic of a natural type IIa colorless diamond with
strong phosphorescence. S. Xu, Y. Xie and B. Wang,
Superhard Material Engineering, 34(5), 2022, 54–58,
https://tinyurl.com/4cx2rvvb (in Chinese with
English abstract).
Growth story of one diamond: A window to the
lithospheric mantle. V. Afanasiev, S. Ugapeva,
Y. Babich, V. Sonin, A. Logvinova, A. Yelisseyev,
S. Goryainov, A. Agashev et al., Minerals, 12(8),
2022, article 1048 (18 pp.), https://doi.org/10.3390/
min12081048.*
Low-temperature annealing and kinetics of
radiation stains in natural diamond. S. EatonMagaña, C.M. Breeding and R. Bassoo, Diamond and
Related Materials, 132, 2023, article 109649 (13 pp.),
https://doi.org/10.1016/j.diamond.2022.109649.
Morphological features and spectral comparisons of
diamonds from three kimberlite belts in Mengyin,
China. C.-F. Zhang, F. Liu, Q. Lv, Y. Wang and
J.-S. Yang, Minerals, 12(10), 2022, article 1185
(15 pp.), https://doi.org/10.3390/min12101185.*
Morphological and surface microtopographic
features of HPHT-grown diamond crystals with
contact twinning. K. Sun, T. Lu, M. He, Z. Song,
J. Zhang and J. Ke, Crystals, 12(9), 2022, article 1264
(15 pp.), https://doi.org/10.3390/cryst12091264.*
Optimal direction and propagation of mid-IR
light inside rough and polished diamonds for
highly-sensitive transmission measurements of
nitrogen content. R.A. Khmelnitsky, O.E. Kovalchuk,
Y.S. Gulina, A.A. Nastulyavichus, G.Y. Kriulina,
N.Y. Boldyrev, S.I. Kudryashov, A.O. Levchenko
et al., Diamond and Related Materials, 128, 2022,
article 109278 (9 pp.), https://doi.org/10.1016/j.
diamond.2022.109278.
Orientational dependences of diamonds grown in
the NiMnCo–silicate–H2O–C system under HPHT
conditions and implications to natural diamonds.
Z. Lu, Z. Wang, S. Wang, H. Zhao, Z. Cai, Y. Wang,
H. Ma, L. Chen et al., ACS Earth and Space Chemistry,
6(4), 2022, 987–998, https://doi.org/10.1021/
acsearthspacechem.1c00381.
Raman spectroscopy study on the surface of high
temperature and high pressure diamond crystal in
geology, rock and minerals. L. Shi, H. Chi,
W. Wang and Y. Yu, Highlights in Science, Engineering
and Technology, 17, 2022, 142–147, https://doi.
org/10.54097/hset.v17i.2562.*
A review on cut proportion of diamond learned
from the experiences at a diamond cutting factory.
H. Yano, Journal of The Gemmological Society
of Japan, 36(1–4), 2022, 10–18, https://doi.org/
10.14915/gsjapan.36.1-4_10 (in Japanese with
English abstract).
FAIR TRADE
Averting your gaze with sustainable, green
marketing claims: A critique of luxury commodity
production sustainability claims, with evidence
from the diamond industry. M.J. Lynch, M.A. Long
and P.B. Stretesky, Sociological Spectrum, 42(4–6),
2022, 278–293, https://doi.org/10.1080/02732173.
2022.2148797.
Critical “loupe” holes: Conflict diamonds and
security threats arising from weaknesses in the
Kimberley Process. M.E. Crouse, National Security
Law Journal, 10(1), 2023, 76–119, https://tinyurl.
com/etjr4krs.*
The dynamics of the illegal ivory trade and the
need for stronger global governance. Z. Miao,
Q. Wang, X. Cui, K. Conrad, W. Ji, W. Zhang, X. Zhou
and D.C. MacMillan, Journal of International Wildlife
Law & Policy, 25(1), 2022, 84–96, https://doi.org/
10.1080/13880292.2022.2077393.
Fighting silicosis in Bahia, Brazil. B. Cook and J.-L.
Archuleta, Gems&Jewellery, 32(2), 2023, 24–27.
Five decades of wildlife protection: An introduction to
CITES. J. Barzdo, Gems&Jewellery, 32(1), 2023, 22–25.
Peace, hope and prosperity through diamond
cutting in Sierra Leone. M. de Witte and F. Lebbie,
Gems&Jewellery, 32(2), 2023, 36–39.
Sustainable coastal business strategies for cultured
pearl sectors: Agenda development for coastarea actors’ collaboration. H. Oe and Y. Yamaoka,
Coasts, 2(4), 2022, 341–354, https://doi.org/10.3390/
coasts2040017.*
738 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
LITERATURE OF INTEREST
GEM LOCALITIES
Corundum genesis at the Blue Jay sapphire
occurrence (British Columbia, Canada) as a record
of metamorphism and partial melting in the
Monashee complex. L. Abdale, P.M. Belley,
L.A. Groat, J. Cempírek, R. Škoda and C. Wall,
Lithos, 438–439, 2023, article 106992 (23 pp.),
https://doi.org/10.1016/j.lithos.2022.106992.
Formation of the nephrite deposit with five mineral
assemblage zones in the central western Kunlun
Mountains, China. X. Zhang, G. Shi, X. Zhang and K.
Gao, Journal of Petrology, 63(11), 2022, article egac117
(16 pp.), https://doi.org/10.1093/petrology/egac117.*
Gem-quality augite from Dong Nai, Vietnam.
Le Ngoc Nang, Lam Vinh Phat, Pham Minh Tien,
Pham Trung Hieu, K. Kawaguchi and Pham Minh,
Gems & Gemology, 59(2), 2023, 182–194,
https://doi.org/10.5741/gems.59.2.182.*
In search of sakura ishi: Cherry blossom stones
[cerasite] from Kameoka, Japan. A. Mathys,
Gems&Jewellery, 32(1), 2023, 50–51.
In situ U–Th–Pb dating of parisite: Implication for
the age of mineralization of Colombian emeralds.
U. Altenberger, Y. Rojas-Agramonte, Y. Yang,
J. Fernández-Lamus, T. Häger, C. Guenter,
A. Gonzalez-Pinzón, F. Charris-Leal et al., Minerals,
12(10), 2022, article 1232 (14 pp.), https://doi.
org/10.3390/min12101232.*
Mining Blue John in 2023. E. Turner and J.-L.
Archuleta, Gems&Jewellery, 32(2), 2023, 32–34.
Nurturing resilience: Overcoming challenges
in the sapphire fields of Australia. D.J. Baral,
Gems&Jewellery, 32(2), 2023, 20–23.
Occurrences and genesis of emerald and other
beryls mineralization in Egypt: A review.
F.M. Khaleal, G.M. Saleh, E.S.R. Lasheen and D.R.
Lentz, Physics and Chemistry of the Earth, Parts
A/B/C, 128, 2022, article 103266 (14 pp.),
https://doi.org/10.1016/j.pce.2022.103266.
Petrology, geothermobarometry and geochemistry of granulite facies wall rocks and hosting
gneiss of gemstone deposits from the Mogok area
(Myanmar). M.M. Phyo, L. Franz, R.L. Romer,
C. de Capitani, W.A. Balmer and M.S. Krzemnicki,
Journal of Asian Earth Sciences: X, 9, 2023,
article 100132 (16 pp.), https://doi.org/10.1016/j.
jaesx.2022.100132.*
The restart of demantoid from Madagascar and its
twinning fire. J.G.G.L. Gem Information, 49, 2023,
15–17 (in Japanese with English abstract).
INSTRUMENTATION AND
TECHNOLOGY
Basics of LA-ICP-MS analysis. K. Emori, Journal of
The Gemmological Society of Japan, 36(1–4), 2022,
19–29, https://doi.org/10.14915/gsjapan.36.1-4_19
(in Japanese with English abstract).
Development of mid-infrared absorption spectroscopy for gemstone analysis. Z. Wang and
H. Takahashi, Minerals, 13(5), 2023, article 625
(9 pp.), https://doi.org/10.3390/min13050625.
Development of UV-Vis-NIR-MIR absorption
spectroscopy for gemstone analysis. Z. Wang
and H. Takahashi, Novel Optical Systems, Methods,
and Applications XXV, 12216, 3 October 2022,
paper 122160R (7 pp. + poster), https://doi.
org/10.1117/12.2624632.
Discussion on detection method of jewelry and jade
by EDXRF. Y. Cheng, H. Zhu, C. Fan, X. Ma, S. Chen,
Y. Huang, J. Gao and W. Wang, Superhard Material
Engineering, 34(4), 2022, 59–66, https://tinyurl.com/
yzmebevd (in Chinese with English abstract).
Imaging-assisted Raman and photoluminescence
spectroscopy for diamond jewelry identification
and evaluation. T.-H. Tsai, Applied Optics, 62(10),
2023, article 2587 (8 pp.), https://doi.org/10.1364/
ao.484366.*
LED for gemstone and jewelry. J.G.G.L. Gem
Information, 49, 2023, 18–21 (in Japanese with
English abstract).
A polynomial interactive reconstruction method
based on spectral morphological features for the
classification of gem minerals using portable LIBS.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 739
LITERATURE OF INTEREST
J. Yan, Q. Li, F. Qin, L. Xiao and X. Li, Journal
of Analytical Atomic Spectrometry, 37(9), 2022,
1862–1868, https://doi.org/10.1039/d2ja00010e.
Study of 405 nm laser-induced time-resolved
photoluminescence spectroscopy on spinel and
alexandrite. W. Xu, T.-H. Tsai and A. Palke, Minerals,
13(3), 2023, article 419 (15 pp.), https://doi.
org/10.3390/min13030419.*
MISCELLANEOUS
The colourful success of the Gemfields’ auction
system. R.G. Sikri, Gems&Jewellery, 32(1), 2023, 56–59.
Describing color: A fool’s guide. R.W. Hughes,
GemGuide, 42(3), 2023, 4–10.
Diamond investments – Is the market free from
multiple price bubbles? M. Potrykus, International
Review of Financial Analysis, 83, 2022, article 102329
(9 pp.), https://doi.org/10.1016/j.irfa.2022.102329.*
Empire builders: The art of branding. G. Dominy,
L. Lauren, H. McCracken, P. Ati and K. Jones,
Gemmology Today, June 2023, 6–13, https://tinyurl.
com/bdn598nc.*
An interesting pair of earrings. L. Rennie, F. Payette
and M. Blackwell, Australian Gemmologist, 28(3),
2023, 152–153.
The new minerals exhibition at the Australian
Museum. R. Pogson, Australian Gemmologist, 28(3),
2023, 146–149.
The regalia of the coronation. C. Blatherwick,
Gems&Jewellery, 32(1), 2023, 38–41.
The Turquoise Museum in Albuquerque, New
Mexico: A rich repository of all things turquoise!
J. Lowry, Rocks & Minerals, 98(5), 2023, 449–454,
https://doi.org/10.1080/00357529.2023.2213154.
NEWS PRESS
The 10 most iconic jewels through history.
D. Woodward, BBC News, 24 February 2023,
https://tinyurl.com/vf8cyhsz.*
Chelmsford: Roman Apollo ring with links
to Snettisham Hoard found. BBC News, 8
April 2023, https://www.bbc.com/news/
uk-england-essex-65202077.*
How more sanctions on Russian diamonds could
affect the global market. E. Paton, New York Times,
28 August 2023, https://tinyurl.com/26xyz8c5.
Inside the emerald mines that make Colombia a
global giant of the green gem. J. Otis, NPR, 11 March
2023, https://tinyurl.com/yvdc3vdd.*
Mourning jewelry leaves the Victorian era behind:
Lab-grown diamonds made with cremation ashes
are just one way people are honoring their loved
ones. A.R. Esman, New York Times, 26 May 2023,
https://tinyurl.com/2p84mphc.
Precious metals, gems, ivory found in artifact-laden
tombs unearthed in Cyprus. S. Shafiq, USA Today,
7 July 2023, https://tinyurl.com/47kk2fxd.*
The revolution underway in India’s diamond
industry. P. Gupta and B. Morris, BBC News,
17 March 2023, https://www.bbc.com/news/
business-64783843.*
ORGANIC/BIOGENIC GEMS
The fossil resins of Europe. M. Kazubski,
Bursztynisko (The Amber Magazine), No. 47,
2023, 86–87, https://www.calameo.com/read/
007323557a467cf9a10df (in English and Polish).*
Origin of fossil resins. A. Matuszewska, Bursztynisko
(The Amber Magazine), No. 47, 2023, 80–84, https://
www.calameo.com/read/007323557a467cf9a10df (in
English and Polish).*
Origins of color in brown mammoth ivory.
Z. Huang, T. Chen, J. Zheng, D. Wang and X. Xu,
Gems & Gemology, 59(2), 2023, 196–209,
https://doi.org/10.5741/gems.59.2.196.*
Preliminary study on infrared holographic imaging
of amber from the Baltic Sea. Y. Yao, H. Huang,
X. Chen, Y. Gui, B. Yang and Z. Zheng, Journal of Gems
& Gemmology, 25(1), 2023, 36–44, https://tinyurl.
com/3dj37w54 (in Chinese with English abstract).*
740 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
LITERATURE OF INTEREST
A review for the gemmological research on amber.
Y. Wang, Y. Li, Z. Shi, F. Liu, F. Liu and Z. Zhang,
Journal of Gems & Gemmology, 24(5), 2022, 55–68,
https://tinyurl.com/4y9punee (in Chinese with
English abstract).*
Spectral and colour characteristics of red series
amber from Myanmar. L. Dong, Journal of Gems
& Gemmology, 24(5), 2022, 87–93, https://tinyurl.
com/4pe8bbrj (in Chinese with English abstract).*
PEARLS
Change of optical properties of akoya pearls with
treatment. S. Tazawa, Journal of The Gemmological
Society of Japan, 36(1–4), 2022, 30–31, https://doi.
org/10.14915/gsjapan.36.1-4_30 (in Japanese with
English abstract).
Cultured pearls soar: High prices and higher
demand. B. Branstrator, GemGuide, 42(4), 2023, 4–7.
Deciphering the color origin of pink conch pearl
using nondestructive spectroscopies and DFT
calculations. C. Chen, J. Yu, X. Ye and A.H. Shen,
Minerals, 13(6), 2023, article 811 (14 pp.),
https://doi.org/10.3390/min13060811.*
Dynamic microstructural characteristics of Edison
pearls cultured in Hyriopsis cumingii. X. Yan,
J. Zhang, J. Sheng, Q. Sun, T. Chen, Y. Zhou, J.
Wang, C. Jia et al., Journal of Materials Science,
57(43), 2022, 20138–20155, https://doi.org/10.1007/
s10853-022-07905-2.
An idea of evaluation of nacre thickness of
nucleated cultured pearls. E. Ito, Journal of The
Gemmological Society of Japan, 36(1–4), 2022, 37–41,
https://doi.org/10.14915/gsjapan.36.1-4_37 (in
Japanese with English abstract).
Nature of pigments in orange and purple coloured
Chinese freshwater cultured pearls: Insights
from experimental Raman spectroscopy and DFT
calculations. C. Chen, J. Yu, C. Zhang, X. Ye and
A.H. Shen, Minerals, 13(7), 2023, article 959 (14 pp.),
https://doi.org/10.3390/min13070959.*
Synchrotron radiation μ-XRF imaging reveals
Mn zoning in freshwater pearls. J. Gao, J. Zhang,
W. Wu, C.K. Yen and W. Su, Journal of Physical
Chemistry C, 126(50), 2022, 21381–21389,
https://doi.org/10.1021/acs.jpcc.2c05988.
Synchrotron radiation μ-XRF imaging reveals oscillatory zoning of freshwater pearls. J. Gao, J. Zhang
and C. Yen, Journal of Gems & Gemmology, 25(1),
2023, 28–35, https://tinyurl.com/5xrh9x8e (in
Chinese with English abstract).*
Synchrotron-based HR-fluorescence and mineralogical mapping of the initial growth stages of
Polynesian cultivated pearls disprove the ‘reversed
shell’ concept. J.-P. Cuif, Y. Dauphin, C. Lo,
K. Medjoubi, D. Saulnier and A. Somogyi, Minerals,
12(2), 2022, article 172 (15 pp.), https://doi.
org/10.3390/min12020172.*
The types of UV-Vis diffuse reflectance spectra of
common gray pearls and their coloring mechanism.
S. Fang, Y. Jiang, J. Yan, X. Yan, Y. Zhou and J.
Zhang, Spectroscopy and Spectral Analysis, 42(12),
2022, 3703–3708, http://www.gpxygpfx.com/EN/
Y2022/V42/I12/3703 (in Chinese with English
abstract).*
UV light resistance test of pearls. R. Wakatsuki,
Journal of The Gemmological Society of Japan,
36(1–4), 2022, 32–36, https://doi.org/10.14915/
gsjapan.36.1-4_32 (in Japanese with English abstract).
Visiting the home of Japan’s cultured pearl farms.
A. Naito, Gems&Jewellery, 32(2), 2023, 28–31.
SIMULANTS
A comparison of the optical and chemical
characteristics of lapis lazuli with attractive
color and its imitation stones. B. Koo,
Wooshin Gem Lab Magazine, 9, 2022, 6–11,
https://tinyurl.com/4nuyb7jh.*
Development of glass-ceramics from soda lime
silica glass waste with addition of kaolin and
coloring oxide for turquoise’s imitation. D. Bootkul
and S. Intarasiri, Vibrational Spectroscopy, 123, 2022,
article 103467 (9 pp.), https://doi.org/10.1016/j.
vibspec.2022.103467.
THE JOURNAL OF GEMMOLOGY, 38(7), 2023 741
LITERATURE OF INTEREST
Preparation and basic properties of praseodymiumneodymium-chromium containing imitation
gemstone glass. S. Zhang, K. Li, J. Pu and W. Ni,
Materials, 15(20), 2022, article 7341 (11 pp.),
https://doi.org/10.3390/ma15207341.*
Synthetic resins in mining simulate amber. A.
Krumbiegel, M. Kazubski, E. Wagner-Wysiecka and
R. Wimmer, Bursztynisko (The Amber Magazine),
No. 47, 2023, 88–91, https://www.calameo.com/
read/007323557a467cf9a10df (in English and Polish).*
SYNTHETICS
Chemical composition and spectra characteristics
of hydrothermal synthetic sapphire. Y. Lü, J. Pei
and Y. Zhang, Spectroscopy and Spectral Analysis,
42(11), 2022, 3546–3551, http://www.gpxygpfx.com/
EN/Y2022/V42/I11/3546 (in Chinese with English
abstract).*
Chinese colorless HPHT synthetic diamond
inclusion features and identification. Y. Ma,
Z. Qiu, X. Deng, T. Ding, H. Li, T. Lu, Z. Song,
W. Zhu et al., Crystals, 12(9), 2022, article 1266
(12 pp.), https://doi.org/10.3390/cryst12091266.*
Comparative study of mineralogical characteristics
of natural and synthetic amethyst and smoky
quartz. K. Liu and Y. Guo, Crystals, 12(12), 2022,
article 1735 (8 pp.), https://doi.org/10.3390/
cryst12121735.*
Comparative study on the quality of HTHP and
CVD single crystal diamond substrates. Y. Yang,
X. Han, X. Hu, B. Li, Y. Peng, X. Wang, X. Hu, X. Xu
et al., Journal of Synthetic Crystals, 51(9–10), 2022,
1777–1784, http://rgjtxb.jtxb.cn/EN/Y2022/V51/
I9-10/1777 (in Chinese with English abstract).*
Evaluating the defects in CVD diamonds: A statistical approach to spectroscopy. M.F. Hardman,
S.C. Eaton-Magaña, C.M. Breeding, T. Ardon and
U.F.S. D’Haenens-Johansson, Diamond and Related
Materials, 130, 2022, article 109508 (22 pp.),
https://doi.org/10.1016/j.diamond.2022.109508.
Giorgia Spezia and the hydrothermal quartz.
E. Costa and R. Navone, Rivista Italiana de Gemmologia/Italian Gemological Review, No. 16, 2023, 51–55.
Not just a pretty face: The history of HPHT
synthetic diamonds. B. West, Gems&Jewellery,
32(1), 2023, 42–45.
Spectroscopic properties of CVD lab-grown
diamond and a typical example: Lightbox. S. Noh,
Wooshin Gem Lab Magazine, 10, 2023, 2–8,
https://tinyurl.com/mv5cjpdb.*
Synthetic diamond identification under X-ray
excitation. L. Cheng, Y. Zhu, R. Lin, Y. Ding,
X. Ouyang and W. Zheng, Cell Reports Physical
Science, 4(1), 2023, article 101208 (15 pp.),
https://doi.org/10.1016/j.xcrp.2022.101208.*
Synthetic morganite: The long journey of
hydrothermal pink beryl. A. Malossi, Rivista
Italiana de Gemmologia/Italian Gemological Review,
No. 16, 2023, 33–44.
TREATMENTS
Application of high-temperature copper diffusion in
surface recoloring of faceted labradorites. Q. Zhou,
C. Wang and A.H. Shen, Minerals, 12(8), 2022, article
920 (13 pp.), https://doi.org/10.3390/min12080920.*
Chemical composition and spectroscopic characteristics of heat-treated rubies from Madagascar,
Mozambique and Tanzania. L. Yang, Q. Lu, D. Ma,
H. Zheng, R. Hu, Z. Shi and B. Qin, Crystals, 13(7),
2023, article 1051 (16 pp.), https://doi.org/10.3390/
cryst13071051.*
Color modification of spinel by nickel diffusion:
A new treatment. M. Jollands, A. Ludlam, A.C. Palke,
W. Vertriest, S. Jin, P. Cevallos, S. Arden, E. Myagkaya
et al., Gems & Gemology, 59(2), 2023, 164–181,
https://doi.org/10.5741/gems.59.2.164.*
Detecting corundum fillers with the long-wave UV
torch. E.B. Hughes, Australian Gemmologist, 28(3),
2023, 150–151.
Difference of lattice radiation damage and spectroscopic characterization in natural and artificial
radiation green diamonds. L. Qi, Z. Zhou, B. Zhao,
C. Zeng and C. Xiang, Journal of Gems & Gemmology,
24(5), 2022, 1–10, https://tinyurl.com/4pn32epe (in
Chinese with English abstract).*
742 THE JOURNAL OF GEMMOLOGY, 38(7), 2023
LITERATURE OF INTEREST
Enhancement of Paraiba tourmaline. J.G.G.L. Gem
Information, 49, 2023, 11–14 (in Japanese with
English abstract).
Gemstone testing during the jewelry manufacturing
process. Lead-glass filled ruby. D. Romanelli and
S. Coppola, Rivista Italiana de Gemmologia/Italian
Gemological Review, No. 16, 2023, 25–31.
Identification method of glue-filled aquamarine.
N. Cao, T. Chen, J. Zheng, X. Chen, Y. Zhuang and
Z. Wang, Journal of Gems & Gemmology, 25(1), 2023,
45–51, https://tinyurl.com/bdepj8y5 (in Chinese with
English abstract).*
Mechanism of Be-thermodiffusion in rutile inclusions of fancy sapphires. M. Rossi, R. Biondi,
R. Rizzi, N. Corriero, F. Sequino and A. Vergara,
Crystal Growth & Design, 22(11), 2022, 6493–6503,
https://doi.org/10.1021/acs.cgd.2c00700.*
Optimized conditions for cobalt diffusion in Sri
Lankan colorless topaz and coloration mechanism
elucidation through spectro-chemical investigation. C.P. Udawatte, S. Abeyweera, L.R.K. Perera,
S. Illangasinghe, C. Weerasooriya, C. Sutthirat, N.
Jayasinghe, T. Dharmaratne et al., Journal of Metals,
Materials and Minerals, 33(1), 2023, 73–81,
https://doi.org/10.55713/jmmm.v33i1.1596.*
Les saphirs chauffés à haute temperature et leurs
inclusions identifiables en gemmologie classique
[Sapphires heated at high temperatures and their
identifiable inclusions in classical gemology].
M. Bouvier, Revue de Gemmologie A.F.G., No. 220,
2023, 22–23 (in French).
The spectroscopy study of different filling
materials in tourmaline. J. Sui, Superhard Material
Engineering, 34(5), 2022, 59–65, https://tinyurl.com/
ycmne9p4 (in Chinese with English abstract).
Study on the common effect of heat treatment,
dyeing or irradiation treatment on UV-Vis diffuse
reflectance spectra of pearls. J. Yan, S. Fang, X. Yan,
J. Sheng, J. Xu, C. Xu and J. Zhang, Spectroscopy and
Spectral Analysis, 42(12), 2022, 3697–3702,
http://www.gpxygpfx.com/EN/Y2022/V42/I12/3697
(in Chinese with English abstract).*
Update of andesine diffusion. J.G.G.L. Gem Information, 49, 2023, 7 (in Japanese with English abstract).
COMPILATIONS
G&G Micro-World. Aquamarine from Xinjiang, China
• Clinochlore and muscovite in quartz from Colorado,
USA • Iridescent ‘insect wing’ in diamond • Patchy
yellow trigon on diamond • ‘Rainbow mountain’ in
diamond • Musical note symbol in diamond • Snailshaped pyrope-diopside inclusion in diamond •
Metal sulfide(?) in garnet • Graphite in pink sapphire
• Night sky scene in yellow sapphire • ‘Eye’ on a
Tridacninae pearl • Thread-like inclusions of serpentine in brown peridot • Metallic platelets in Paraíba
tourmaline • Triplite inclusions in Chinese quartz •
Geocronite in fluorite. Gems & Gemology, 59(2), 2023,
222–231, https://tinyurl.com/jv9rnphm.*
Gem News International. Suite of Colombian
emerald-and-matrix cabochons • Calcite in a pearl
from Pinctada maculata • Unusual metallic core in a
natural P. radiata pearl • Saltwater clamshell beads
in freshwater cultured pearls • Quartz with ‘rabbit
hair’ inclusions • Heat-treated rubies from Greenland
• Treatment for creating phantom structure in opal
• Spring 2023 auction highlights • 2023 Sinkankas
Symposium • Sustainability panels at JCK Las Vegas.
Gems & Gemology, 59(2), 2023, 242–258, https://
tinyurl.com/yy2p3rh2.*
Lab Notes. Star aquamarine • Faceted brucite •
Natural diamond with CVD-like fluorescence pattern
• Yellow zoning in pink diamonds • Glass imitation
of cat’s-eye chrysoberyl • 34.59 ct CVD synthetic
diamond • CVD synthetic diamonds with invisible
markings • Two pearls of Indian cultural significance
• 19+ mm South Sea bead-cultured pearl • Linear
structures in non-bead cultured pearls • Plastic imitations of emerald • Pink zektzerite. Gems & Gemology,
59(2), 2023, 210–222, https://tinyurl.com/mrxr4cd9.*
*Article freely available for download, as of press time
BOOK NOW!
To register and buy tickets visit:
gem-a.com/event/conference-2023
This year’s Conference
boasts an incredible
line-up of six expert
speakers and is a mustattend event for anyone
interested in gemmology.
The Conference will be
held at etc.venues County
Hall, which overlooks the
River Thames and the
Houses of Parliament.
Bringing together the greatest minds in Gemmology
November 5
etc.venues County Hall, London
Gem-A
Conference
2023
REASONS TO ATTEND
● Amazing line-up of six experts in their
respective fields.
● Enjoy a rare opportunity to network
with fellow gemmologists and industry
professionals in a relaxed environment.
● Enhance your knowledge and stay up-to-date
with developments in our evolving sectors.
● Exclusive workshops and tours including
private viewings.
● Add to the Conference experience by joining
us for the Gem-A Conference dinner on the
evening of November 5.