Title: Brazilian Alexandrite Update Abstract: Figure 1. This pair of Brazilian alexandrites (2.41 ct and 6.7 mm each) is photographed in daylight (left) and incandescent light (right). Photos by Kevin Schumacher, courtesy of Gil International.
Gil International’s booth at the AGTA show featured something out of the ordinary: a display case with lighting selected to reveal the color change of their Brazilian alexandrites, from blue-green in daylight to reddish purple in incandescent light. Goel “Gil” Gul built the case himself, and he said it has drawn traffic to the booth over the years. Based in New York, Gil International began exhibiting in Tucson 30 years ago; 2019 was their 19th year at the AGTA show.
Gil International specializes in natural Brazilian alexandrite (see above), which exhibits a strong color change. Alexandrite was first found in Russia’s Ural Mountains in the 1830s. It wasn’t until the discovery of Brazilian sources in the late 1980s, most notably Lavra de Hematita (also called Nova Era or Itabira), that greater quantities became available, though alexandrite is still considered rare.
Alexandrite has been in greater demand over the last 15 years, Gul said, but business has been slow the last two. In the past decade, his sales to a company that caters to cruise ships have been particularly strong. He attributes this to people “always looking for something unusual” and having more time to look at jewelry while on vacation. When Gul entered the industry, aquamarine, tourmaline, and zircon were big. Sapphire has always been very strong, he said, but ruby has come down in the last five years. The demand for stones rises and falls over the decades based on jewelry house promotion, he said, citing Tiffany & Co.’s marketing campaign after the discovery of tanzanite in 1967. He added that more people are buying brown diamonds, previously considered undesirable, because of Le Vian’s branding and heavy advertising of “chocolate diamonds.”

	Brazilian alexandrite update

Gul said that every source has different color; for example, Sri Lankan alexandrite is typically an olive green in daylight, while Brazilian stones are more blue-green. He acknowledged that only laboratory testing can definitively determine country of origin, but he can often make an educated guess based on color. He noted that alexandrites from India are sometimes reported as Brazilian, but he can tell that they are from India because the color change is not as strong and the green tends to be lighter.
Born in Afghanistan and educated in Israel and New York, Gul worked in accounting for a decade before being introduced to the gem and jewelry industry by his four older brothers. They were already selling ruby and sapphire, so they sent him to Brazil. On his first trip to Teófilo Otoni, Minas Gerais, in 1990, Gul bought emerald. He saw some alexandrite but didn’t buy any until his next visit. He later found out that the stones were from Lavra de Hematita.
“You buy one stone, but you’ve got three stones,” he said, referring to alexandrite’s color change. “I felt I could improve my life with this stone.”
Gul bought alexandrite from a broker in Teófilo Otoni for several years and contacted the miner directly about 15 years ago. The miner didn’t sell the rough; he had the stones cut in Hong Kong and Thailand, so he controlled the production entirely. Gul began to buy directly from him in Hong Kong.
Gul found that unlike many in the industry, the miner did not like to bargain. So he accepted the miner’s prices, and as Gul bought more stones, the miner gave him better deals. As Gil International became stronger in alexandrite, Gul and the miner became good friends. Gul has bought almost all of his alexandrite from him.
“The way to make a better business is to find a relationship with the miner,” Gul said. “If you have a good relationship, he can trust you; you can trust him. Sometimes even big companies with big money try to bargain, so they don’t find a relationship with the miner and can’t buy from him.”
Gul spoke of turning down the miner’s repeated offers to buy goods on memo—including an offer of $12 million of goods in 2010, when the miner closed seven stores in Greece after the 2008 market crash. “I buy what I can,” he said. “And he feels that I’m different [than other dealers] and gives me a chance to do more business.” Source: GIA @topic:2


Title: Winter 2023 G&G Available Now Abstract: The Winter issue of Gems & Gemology is bursting with exciting new content! In addition to three feature articles, it offers a field report, a new inclusions chart, the latest installment of Colored Stones Unearthed, and as always, our regular quarterly sections.
TOPAZ FROM MASON COUNTY, TEXAS
A team led by Dr. Roy Bassoo reports on Texas topaz, covering the gem’s mining history in Mason County, followed by a study of its gemological and compositional characteristics. The authors also use machine learning and statistical modeling of trace element data from worldwide topaz sources to provide a basis for determining geographic provenance.
BOHEMIAN GARNETS AS DECORATIVE MATERIALS FOR GLASS VESSELS FROM THE LATE SIXTEENTH TO EARLY EIGHTEENTH CENTURIES
Dr. Karl Schmetzer and fellow authors research a method of setting cut garnets on glass objects, examining vessels at two museums in Germany. The article begins with the historical and legal context of the technique, invented by Claudius vom Creutz in Nuremberg circa 1591, followed by the results of their study.
A UNIQUE PETRIFIED TREE FERN FROM NORTHEAST CHINA
A petrified tree fern fossil from the Cretaceous period has drawn attention since its discovery in northeast China in 2010. Ying Yan and coauthors share their study of six samples displaying golden yellow to brown colors and distinct plant structure patterns, identifying chalcedony as the primary mineral component in the material.
SLOVAK OPAL: A NEW LIFE FOR A HISTORICAL GEM
This field report by Dr. Peter Semrád follows the resurgence of opal mining in Slovakia, which yields both precious and common varieties. Historical, geological, and mineralogical details are followed by accounts of recent mining and production based on the author’s visit to the locality and interviews with heads of the country’s two main opal producers.
MICRO-FEATURES OF BERYL CHART
Nathan Renfro, John Koivula, and coauthors add to the G&G series of micro-feature charts with this display of inclusions found in natural beryl. The wall chart, which presents 30 superb photomicrographs, is included in every printed copy of this issue, and a laminated version is available for sale in the GIA Store.

LAB NOTES
GIA’s global laboratory staff present their latest findings in the Lab Notes section, including a unique bicolor natural diamond exhibiting two distinctly different colors, a natural saltwater pearl containing a pair of foraminifera-like spheres, and a rare encounter with a large faceted orange-yellow sodalite.
MICRO-WORLD
The Micro-World section, which showcases the inner beauty of gemstones, features a stunning “sun spangle” in amber, a cross pattern visible in a natural diamond, remarkable hollandite crystals in a Brazilian amethyst, and more.
COLORED STONES UNEARTHED
Colored Stones Unearthed returns to explore the formation of sedimentary rocks, gems formed in sedimentary environments, and gems found in sedimentary environments that formed elsewhere. The column also covers the alluvial mining of these gems.
GEM NEWS INTERNATIONAL
Finally, Gem News International contributors report on a variety of topics, including a Vietnamese garnet displaying 14 trapiche patterns, an update on Virtu Gem’s ethical supply chain practices, and a summary of the fall 2023 auction season, which was marked by several surprising twists. Source: GIA @topic:7


Title: More on Virtu Gem’s Ethical Supply Chain Practices Abstract: Figure 1. These indicolite tourmalines (9.27 and 6.16 ct) from Zambia are among the variety of gems Virtu Gem offers. Photo by Robert Weldon.
We first covered Virtu Gem at the 2023 Ethical Gem Fair in Tucson (see Spring 2023 GNI, pp. 122–125). Virtu Gem gives artisanal and small-scale miners, traders, and cutters in Kenya, Malawi, and Zambia formal access to the international market and offers training in cutting, basic gemology, and mine safety.
The gems Virtu Gem sells (see figure 1) are cut in the source country and tracked with Provenance Proof Blockchain. One of Virtu Gem’s efforts is training artisans in cutting and polishing standards to meet international market expectations. Percy Maleta, Virtu Gem’s country exporter and ambassador in Malawi, said the training has attracted many cutters there and allowed them to sell gems at premium prices.

Figure 2. Gemstone cutters in Kenya, Malawi, and Zambia developed cuts to represent their countries in Virtu Gem’s National Gem Cut Course. Left to right: the Kenya Cheetah Head, Zambia Eagle, and Malawi Mbuna Fish cuts in aquamarine, amethyst, and rhodolite garnet. Photo courtesy of Virtu Gem.
In 2022, Virtu Gem launched the National Gem Cut Course in the three countries. In online workshops led by Adriano Mol from the University of Minas Gerais State, cutters learned facet development and brainstormed to design gem cuts to represent their nations. The resulting cuts (figure 2) resembled a cheetah head for Kenya, the mbuna (cichlid) fish for Malawi, and the eagle for Zambia. Buyers can order gemstones from each country in its respective cut.
Virtu Gem has received two grants from the World Bank as well as assistance from other organizations. Rio Grande donated a GemLightbox, and Virtu Gem purchased more for its three country coordinators. The GemLightboxes allow traders to upload photos and videos of gems to the online sales platform rather than export stones on consignment. In addition, Gemworld donated its World of Color books to each country coordinator, which help traders evaluate color and cut and set prices.
The donations have also been instrumental in Virtu Gem’s work with the National Gem Cutting School in Zambia, where students use the books and GemLightboxes. Virtu Gem cofounder Susan Wheeler said there are many gem cutters in Kenya, and she would like to establish a gem cutting program for women in Malawi.
Wheeler said gemology students should understand the ethical issues inherent in the traditional gemstone supply chain and the importance of cutting in the source country. She emphasized the importance of knowing that prices are based on not only the gemstones but also the labor of the miner and the jewelry manufacturer and other costs.

Figure 3. Virtu Gem’s Kenya country coordinator, Caroline Muchira, with Nadan tsavorite mine manager Daniel Chege (left) and owner John Kimuyu (right). Photo courtesy of Virtu Gem.
Virtu Gem’s country coordinator for Kenya, Caroline Muchira (figure 3), is a gem cutter by trade. While working full-time in logistics, she was inspired to travel more than 300 km by bus every weekend from Nairobi to Voi to visit the mines and talk to traders. “I was fascinated by the gemstones and how the miners could tell the difference between green garnet, green tourmaline, and pieces of green glass,” Muchira said. She planned to study gemology in retirement, but in 2009, after the company she worked for was sold, she sold all of her belongings to earn her Graduate Gemologist diploma at GIA’s Thailand school. During Muchira’s visits to Voi, she saw the issues the miners faced, especially women and youth. “Often they are unable to sell their stones at a fair price to middlemen, whose aim is to strike the lowest possible deal, leaving miners barely able to eke out a living,” she said. Virtu Gem’s system focuses on fair pricing, and Muchira now runs the organization’s pricing workshops.
Muchira’s ability to earn a GG is not the norm. Maleta said many in Malawi’s gem trade are interested in taking GIA courses but can’t afford it. “In a country with more than 60,000 artisanal and small-scale miners, Malawi probably only has two or three GIA graduates,” he said.
The communities Virtu Gem works with produce a wide variety of gemstones, but they have yet to access some resources. While some artisanal and small-scale mining (ASM) of emeralds occurs in Zambia, Wheeler pointed out, the miners are largely unable to access the more than 400 ASM emerald concessions in Zambia, in the same area as Gemfields. Two women they work with in Zambia have a digger but can’t afford the fuel to run it. “They could be producing the same quality emerald as Gemfields,” Wheeler said. “They can’t afford to do it on a regular basis, and loans are very expensive. We want to support the emerald mining. So we’re trying to work on how to go forward with sourcing and getting more supply with emeralds.”
Virtu Gem is part of the United Nations Conscious Fashion and Lifestyle Network, which highlights collaborations that further the UN’s Sustainable Development Goals (SDGs). Virtu Gem’s efforts are associated with six of the SDGs: ending poverty, ending hunger, gender equality, decent work, inclusive and sustainable industrialization, and reducing inequality. “We’re going to continue to align everything that we do in Virtu Gem with the Sustainable Development Goals so people can see that framework and what gemstones can do to make progress,” Wheeler said. Source: GIA @topic:10


Title: Quarterly Crystal: Hillocks on Beryl Abstract: Figure 1. Measuring 22.28 mm in length and weighing 31.06 ct, the outer pinacoidal surface on the termination of this Pakistani aquamarine crystal is decorated with numerous hexagonal growth hillocks. Photo by Nathan Renfro.
Whenever we study natural uncut gem minerals, we carefully examine all outer surfaces for any photogenic etch figures or growth hillocks that might yield interesting and educational photographs. For this issue’s Quarterly Crystal, we recently had the opportunity to study a very well-formed, gem-quality aquamarine crystal supplied by Ali Shad of Shad Fine Minerals in Gilgit-Baltistan, Pakistan. The aquamarine, pictured in figure 1, was reportedly from the Qandahar mine, located in the Braldu Valley, Shigar District, Gilgit-Baltistan, Pakistan.
At 31.06 ct with corresponding measurements of 22.28 × 14.50 × 11.24 mm, this aquamarine did not show etch figures on any of its crystal faces, proving that the beryl had not gone through post-growth dissolution. However, examination showed that the pinacoid was completely covered with small hexagonal growth hillocks (figure 2) of the type discussed by John Sinkankas in Emerald and Other Beryls (1981) and illustrated on page 273. The hillocks on the terminal pinacoid, which were all generally of the same small size, blanketed the termination completely. Under high magnification, the hexagonal hillocks appeared very complex in form (figure 3). Their sharp, pristine, geometric habit once again illustrated that post-growth dissolution of this crystal had not taken place.

Figure 2. The generally uniform size of the numerous growth hillocks on the terminal pinacoid of the aquamarine is clearly shown in this shadowed reflected light image. The bright colors result from light interacting with thin-film separations in the body of the aquamarine. Photomicrograph by Nathan Renfro; field of view 7.97 mm.

Figure 3. The complexity of some of the hexagonal growth hillocks on the pinacoid of the aquamarine is shown in closer detail in this differential interference contrast image. Photomicrograph by Nathan Renfro; field of view 2.32 mm. Source: GIA @topic:3


Title: Demantoid, Andradite, and Grossular from Mexico Abstract: Figure 1. Demantoid garnet (0.84 ct on the left and 0.28 ct on the right) and an orange grossular garnet (0.55 ct) from Sonora, Mexico. Photo by Diego Sanchez.
Iridescent andradite garnet is an interesting phenomenal stone that was initially produced in Nevada but has also been found in Mexico, Japan, and New Mexico. A small parcel consisting of three stones (figure 1) was recently submitted to GIA’s Carlsbad laboratory and contained some new gem material from the iridescent andradite deposit in Mexico. The deposit is located high in the Sonoran Sierra in the Mexican state of Sonora about 145 km northeast of the city of Hermosillo. The stones were provided by Marion Alberto Márquez Suárez, who works with the mine owner, Salvador Barba.

Figure 2. Mineral inclusions in a Mexican demantoid. Photomicrograph by Aaron Palke; field of view 1.26 mm.
Standard gemological testing gave a refractive index of 1.740 for the grossular garnet and over-the-limit readings for the demantoid garnets. All three samples were inert to both long-wave and short-wave ultraviolet light. Fingerprints and fields of fluid inclusions as well as colorless and dark crystal inclusions were observed (figure 2). The inclusion scenes were reminiscent of skarn-related demantoid garnet from Namibia and Madagascar rather than the horsetail inclusion scenes noted in serpentinite-related demantoid from Russia. Trace element chemistry was collected as part of an ongoing project for demantoid origin determination. Curiously, the demantoid garnets had low gallium levels ranging from 0.45 to 1.96 ppm. This is more in line with serpentine-related demantoid, with gallium less than 1 ppm, than with skarn-related demantoid, which always has gallium levels above 2 ppm. Chromium was also below detection limits, which is consistent with iron-colored demantoid from skarn-related deposits. While these Sonoran demantoid and other garnets are not currently on the market, the miners have produced up to 7 kg of the material over the last 10 years. Source: GIA @topic:2


Title: Texas Topaz, Slovak Opal, a Beryl Inclusions Chart, and More Abstract: Welcome to the Winter 2023 edition of Gems & Gemology ! This issue brings an exciting conclusion to the volume year with three feature articles, a field report, a colorful new inclusions chart, and the return of the Colored Stones Unearthed column along with our other regular columns.
“…a prized gemstone from the United States: Texas topaz, sought after for its domestic provenance and rare natural blue color.”
Our first article explores a prized gemstone from the United States: Texas topaz, sought after for its domestic provenance and rare natural blue color. Dr. Roy Bassoo and coauthors begin with a historical account of topaz from Mason County, Texas, followed by discussion of its geologic origin, compositional characteristics, manufacture, and significance to the gem trade. In addition, the authors seek to provide a basis for determining geographic provenance.
Next, Dr. Karl Schmetzer and fellow researchers investigate a technique for setting cut garnets on glass objects, invented by Claudius vom Creutz of Nuremberg in the late sixteenth century. Examining two glass vessels at museums in Germany, the authors analyze the stones decorating the objects and the methods used to attach them.
Petrified tree fern from northeast China is the topic of our next article. A team led by Ying Yan reports on the gemological properties, chemical composition, and appearance of this material, which displays a beautiful pattern and is being used in intricate carvings in China.
Our fourth article, a field report from Dr. Peter Semrád, presents the revival of Slovak opal mining. It provides a brief history of mining in the area and details on geology and mineralogy, followed by coverage of recent mining activity, production, and marketing.
To close out our features, GIA researchers led by Nathan Renfro and John I. Koivula offer a captivating look at the internal features of beryl, with a foldout chart featuring 30 remarkable photomicrographs. Laminated versions of the chart, along with the six other inclusion charts in the series—emerald, sapphire, ruby, diamond, opal, and spinel—are available at store.gia.edu.
G&G’s regular columns continue to provide the latest gemological findings. Noteworthy updates from GIA laboratories are summarized in Lab Notes, including an HPHT-treated laboratory-grown diamond featuring dramatic color zoning, an antique Indian-style headdress decorated with seed pearls, and a rare faceted thomsonite. Micro-World showcases the inner landscapes of gemstones with striking hollandite crystals in a Brazilian amethyst, a stress halo resembling a butterfly in a natural diamond, a metal sulfide crystal suspended in a padparadscha sapphire, and more. Colored Stones Unearthed returns in this issue, covering the formation and mining of gemstones from sedimentary rocks. Finally, highlights from the Gem News International section include reports on pyritized triceratops fossils from South Dakota, training for artisanal diamond miners in Liberia, and a recent discovery of blue amblygonite-montebrasite from Rwanda.
We hope you enjoy the latest edition of Gems & Gemology ! Source: GIA @topic:7


Title: Fall 2023 G&G Available Now Abstract: The Fall issue of Gems & Gemology has a wide range of colored stone topics in store, from the cause of color in yellow sapphire to the characterization of Oregon sunstone, Ukrainian beryl, and British Columbian iolite. In addition to the four feature articles and our quarterly sections, we see the return of Diamond Reflections and the 2023 G&G Challenge results.
YELLOW SAPPHIRE: NATURAL, HEAT-TREATED, BERYLLIUM-DIFFUSED, AND SYNTHETIC
Dr. John Emmett and fellow researchers share their in-depth study of the various chromophores responsible for color in natural, heat-treated, beryllium-diffused, and synthetic yellow sapphire. Their results reveal that Fe3+, a trapped hole associated with iron (h•-Fe3+), or a combination of the two are involved in the coloration of natural and treated yellow sapphire, while color in synthetic yellow sapphire is attributed to the Ni3+ chromophore or a combination of Ni3+ and Cr3+.
SPECIAL COLORS AND OPTICAL EFFECTS OF OREGON SUNSTONE: ABSORPTION, SCATTERING, PLEOCHROISM, AND COLOR ZONING
Dr. Shiyun Jin and colleagues investigate the special colors and optical effects caused by metallic copper inclusions in Oregon sunstone using samples from various mines. Their study covers the absorption and scattering of light as well as pleochroism and color zoning in this increasingly popular gemstone from the United States.
ETCH PITS IN HELIODOR AND GREEN BERYL FROM THE VOLYN PEGMATITES, NORTHWEST UKRAINE: A DIAGNOSTIC FEATURE
The Volyn pegmatite field in Ukraine is known for the production of green beryl and the yellow beryl variety heliodor. Led by Dr. Gerhard Franz, researchers present their study examining the dissolution features of Ukrainian heliodor and green beryl and offer criteria to distinguish them from samples found in other localities.
IOLITE FROM THE THOR-ODIN DOME, BRITISH COLUMBIA, CANADA: GEOLOGY, CHEMICAL COMPOSITION, INCLUSIONS, AND CAUSE OF CHATOYANCY
Dr. Philippe Belley reports on gem-quality cordierite from two recently discovered occurrences in British Columbia—Blue Arrow and Blue Bear. The paper details the geological setting and gemological properties of this violet-blue iolite and notes the potential for future discoveries in the area.
LAB NOTES
GIA’s global laboratory staff share their latest findings in the Lab Notes section, including two traditional Indian pearl submissions to the Mumbai lab—a Bombay pearl bunch and two pearl nose rings—and a ruby filled with zinc glass examined in the Carlsbad lab.
MICRO-WORLD
The Micro-World section continues to highlight fascinating gem inclusions with an intricate moiré pattern in purple spinel, blade-like magnetite inclusions in peridot, brown matrix in an Armenian turquoise sphere mimicking planet Earth, and more.
DIAMOND REFLECTIONS
Diamond Reflections returns to explore diamonds formed within eclogitic mantle host rocks and what they reveal about Earth’s dynamic processes.
GEM NEWS INTERNATIONAL
Finally, GNI contributors report on new occurrences of basalt-related gems in southeast Vietnam, an assessment of responsible pearl farming in Australia, the opening of the Gübelin Gem Museum in Switzerland, and more. Source: GIA @topic:3


Title: Cause of Color in Yellow Sapphire, Plus Characterization of Oregon Sunstone, Ukrainian Beryl, and British Columbian Iolite Abstract: Welcome to the Fall 2023 issue of Gems & Gemology ! This issue delivers four feature articles covering a range of colored stone topics, from a color study of yellow sapphire to a new source of violet-blue iolite in Canada.
“…investigate the various chromophores responsible for color in four types of yellow sapphire—natural, heat-treated, beryllium-diffused, and synthetic.”
In our lead article, Dr. John Emmett and coauthors investigate the various chromophores responsible for color in four types of yellow sapphire—natural, heat-treated, beryllium-diffused, and synthetic. These chromophores include Fe3+, a trapped hole associated with iron (h•-Fe3+), and a combination of the two, all of which are involved in the coloration of natural and treated yellow sapphire. Synthetic yellow sapphire, on the other hand, is usually colored by the Ni3+ chromophore or by a combination of Ni3+ and Cr3+.
Next, Dr. Shiyun Jin and colleagues share their research on the special colors and optical effects caused by metallic copper inclusions in Oregon sunstone. Using samples from different mines in Oregon, they explore absorption and scattering, pleochroism, and color zoning in this gem-quality feldspar known for its wide range of beautiful colors.
A team led by Dr. Gerhard Franz reports on the morphological characteristics of green beryl and the yellow beryl variety heliodor from the Volyn pegmatite field in Ukraine. The authors observe an abundance of characteristic etch pits throughout the samples and offer details on distinguishing Volyn green beryl and heliodor from those found in other localities.
Dr. Philippe Belley contributes our final feature article, an examination of violet-blue iolite from new deposits in the Thor-Odin dome in British Columbia, Canada. Various samples are analyzed to reveal the nature of their chemical composition, mineral and fluid inclusions, and chatoyancy. The abundance of cordierite-rich rocks in the Thor-Odin dome indicates potential for future iolite discoveries in the area.
G&G’s regular columns contain exciting gemological findings from all over the world. Lab Notes details recent noteworthy submissions to GIA’s laboratories, including a 4.04 ct ring fashioned from a single-crystal CVD-grown diamond, a nacreous atypical bead cultured pearl featuring a flame-like surface structure, and a heart-shaped ruby filled with zinc glass. Observations of fascinating internal features are captured in the Micro-World section, including a rare iridescent ferropericlase in brown diamond, bladed columbite crystals in topaz, and zigzag-patterned fingerprints in blue sapphire. Diamond Reflections returns in this issue, focusing on diamonds formed within eclogitic mantle host rocks. Finally, Gem News International offers brief studies of Burmese chameleon amber, Guatemalan omphacite jade, and other gem materials, as well as coverage of the recent Turquoise United conference and the Chicago Responsible Jewelry Conference.
Congratulations to this year’s G&G Challenge participants who received a perfect score! See a list of the top scorers on page 322. Thank you to those who put their knowledge to the test.
We hope you enjoy the latest edition of Gems & Gemology ! Source: GIA @topic:3


Title: Nickel-Diffused Spinel, Vietnamese Augite, Brown Mammoth Ivory, and More… Abstract: Welcome to the Summer 2023 issue of Gems & Gemology! Loaded with noteworthy content, the articles in this volume cover timely topics, such as a new treatment process identified in natural spinel, a recent source of augite in Vietnam, and research identifying the origin of the surface color of brown mammoth ivory.
“…an undisclosed diffusion treatment process for spinel that is being used to convert lightly colored gems to hues ranging from green to blue.”
In our lead article, Dr. Michael Jollands and fellow GIA researchers report on an undisclosed diffusion treatment process for spinel that is being used to convert lightly colored gems to hues ranging from green to blue. Testing a set of spinel samples represented as “cobalt diffused” revealed that the stones were actually diffused with nickel. With this treatment now present in the gem market, the authors suggest identification criteria for spinel samples within the green to blue color range.
Next, a team led by Le Ngoc Nang investigates a variety of gem-quality augite from Dong Nai, Vietnam. The magnesium-rich augite, characterized by its intense dark orangy brown or dark green color under transmitted light, has potential use in jewelry and as a carving material.
Another carving material, mammoth ivory, is typically found with a brown surface color. Our third article, from Zhaoying Huang and coauthors, examines the origin of this color. They determine that iron oxides and sulfides and manganese oxides and hydroxides crystallized on the mammoth ivory’s surface while underground, causing it to turn brown.
Our regular columns offer a host of interesting finds from all over the globe, including an aquamarine displaying asterism, a CVD-grown diamond over 34 carats, and an exceptionally large South Sea cultured pearl in the Lab Notes section. Explore the inner wonders of gemstones in Micro-World, with a feather inclusion resembling a mountain range in natural diamond, metallic platelets in Brazilian Paraíba tourmaline, an intriguing metal sulfide crystal in garnet, and more. Colored Stones Unearthed returns in this issue, covering gemstones that formed through metamorphic processes. Highlights from the Gem News International section include the characteristics of treated rubies from Greenland as they become more common in the market, the 2023 Sinkankas Symposium, and the latest auction season. Also in this issue, we put fire obsidian In the Spotlight. Tom Dodge’s impressive lapidary work reveals the vivid spectrum of iridescent colors in this rare volcanic glass found only in the Glass Buttes region of Oregon.
Lastly, we invite you to join the G&G Facebook group (facebook.com/groups/giagemsgemology). Since its launch in February 2020, our growing community has surpassed 35,000 members. Thank you for your continued support and interest in Gems & Gemology! Source: GIA @topic:13


Title: 2023 Sinkankas Symposium Abstract: Brendan Laurs, Meg Berry, and Aaron Celestian at the Sinkankas Symposium. Photos by Judy Colbert.
The Nineteenth Annual Sinkankas Symposium was held at GIA in Carlsbad, California, on April 22. Cohosted by GIA and the Geo-Literary Society, the event’s theme was “San Diego County Gems and Minerals.” Pink tourmaline, kunzite, spessartine garnet, and aquamarine were the focus of 11 presentations (see above).
Emcee Robert Weldon (GIA, Carlsbad) welcomed the capacity crowd to the first in-person Sinkankas Symposium since 2019. Dr. Raquel Alonso-Perez (Mineralogical and Geological Museum, Harvard University) recounted the history of the Pala Chief mine starting in the nineteenth century. Bill Larson and son Will Larson (Pala International, Fallbrook, California) examined the tourmalines of the Pala Gem Mining District and the Himalaya mine, respectively. Brendan Laurs (Journal of Gemmology) overviewed the geology of San Diego County pegmatites. Nathan Renfro (GIA, Carlsbad) showed fascinating inclusion features of various gem minerals from the county. Dr. Skip Simmons (Maine Mineral and Gem Museum, Bethel, Maine) detailed the tourmaline mineral group’s compositional variation, crystal structure, and classification.
Cal Graeber (Fallbrook, California) shared insights based on more than 50 years of experience mining and collecting San Diego County minerals. Lapidary artist Meg Berry (Megagem, Fallbrook, California) shared her decades of experience cutting locally mined tourmalines and showed several of her award-winning creations. By video, Paula Crevoshay (Albuquerque, New Mexico) looked back on her love affair with the gems of Southern California, which have often been incorporated into her acclaimed jewelry designs. Dr. Aaron Celestian (Natural History Museum of Los Angeles County) spoke on the use of gems to illuminate art and science. Using the museum’s special exhibit of Crevoshay jewelry as an example, he explained its integration with social media and traditional print media to communicate scientific content. Dr. George Rossman (California Institute of Technology, Pasadena) joined Dr. Aaron Palke (GIA, Carlsbad) in examining the range of colors and color-causing elements in San Diego County gem minerals.
The next Sinkankas Symposium, scheduled for May 2024 in Carlsbad, will be on Burmese gems from Mogok. Source: GIA @topic:7


Title: Susan Jacques Receives Robert M. Shipley Award Abstract: Susan Jacques accepts the Robert M. Shipley Award at the American Gem Society’s 2023 Conclave in Louisville, Kentucky. Courtesy of AGS.
Susan Jacques, GIA’s president and CEO, has received the American Gem Society’s Robert M. Shipley Award, honoring her steadfast commitment to the jewelry industry. Named for the founder of GIA and AGS, the prestigious award was presented to Jacques at the AGS Conclave in Louisville, Kentucky, on May 2, 2023 (see above).
Jacques previously served as president and CEO of Borsheims in Omaha, Nebraska, one of the nation’s largest independent jewelry stores, where she reported directly to Warren Buffett. She served on GIA’s Board of Governors beginning in 1996 and held the chair position from 2008 to 2013 before her appointment as president and CEO in 2014. Jacques holds a Graduate Gemologist diploma from GIA and is a fellow of the Gemmological Association of Great Britain. She is the sixth recipient from GIA to win the award. Source: GIA @topic:11


Title: Pink Zektzerite Abstract: An exceptional pink zektzerite, cut as a square modified step cut, measuring 8.08 × 7.39 × 6.89 mm and weighing 2.95 ct. Photo by Diego Sanchez.
Zektzerite, a member of the tuhualite group, is a very rare collectible mineral currently mined from only two sources: Okanogan County in the U.S. state of Washington (Spring 2011 Gem News International, p. 61), and the Darai-Pioz Valley in Tajikistan (L.A. Pautovet et al., “Zektzerite—occurrence in Tadzhikistan,” Mineralogicheskii Zhurnal, Vol. 14, pp.  75–78). With the chemical formula NaLiZrSi6O15, these rare crystals are found in miarolitic cavities in riebeckite granite, along with many other rare minerals. The zektzerite crystals found in these locations are primarily between 4 mm and 15 mm and usually yield small faceted gems weighing less than 2 ct. This material is typically found with a low transparency and muted color saturations. Perfect cleavage in two directions and a brittle tendency make this fragile stone very difficult and risky to cut. Due to its low durability and overall dull appearance, collectors tend to leave zektzerite in its natural rough state.
An outstanding example of faceted gem-quality zektzerite (see above) was recently submitted to GIA’s Carlsbad laboratory. The stone weighed 2.95 ct, measured 8.08 × 7.39 × 6.89 mm, and had a refractive index ranging between 1.578 and 1.584. A specific gravity of 2.81, along with Raman and infrared spectroscopic testing, all matched zektzerite, with no indication of dye or polymers. The outstanding pink color, relatively high clarity, and impressive size of this stone sets this specimen far above any other faceted zektzerite previously reported. Source: GIA @topic:2


Title: Rock Buttons from the United States Abstract: Figure 1. These rock buttons were seen in Tucson. Bottom row, left to right: blue veil quartz from Washington, rhodonite from Colorado, amazonite from Virginia, serpentine from California, black jasper from Oregon, copper-infused brick from Michigan, jasper from Idaho, oligoclase from Nevada, fossilized coral from Alaska, polka-dot agate from Oregon, and lemon chrysoprase from Australia. Top row: glacier stone from Idaho, bertrandite from Utah, and black jasper from Oregon. Courtesy of Columbia Gem House. Photo by Eric Welch.

              At the AGTA show, Columbia Gem House (Vancouver, Washington) introduced its American rock button collection. The rocks were collected from about 25 different states, then processed and finished in the company’s own cutting facilities. The rocks are sliced and shaped into round buttons and drilled through along different directions. Each button is about 3–4 mm thick and 1–3 cm in diameter. Some are polished, while others have a dull finish. Natural gemstones are mounted in some of the rock buttons, bringing out the colors of both.

The collection features a wide variety of rocks (figure 1). Blue veil quartz, a combination of quartz matrix with blue azurite veins, was discovered in Washington state. Perhaps the most interesting item is copper-bearing brick from a Michigan copper smelter. For years, melted copper dropped on the floor and sealed the fractures in the bricks, giving them a unique look after polishing. Green serpentine, the California state rock, is a metamorphic rock composed of magnesium-rich silicate minerals. Amazonite from Virginia is the beautiful bluish green variety of microcline. With some minor albite stripes, it displays an alternating blue and white pattern. From Utah comes bertrandite, a beryllium source composed of many different minerals. Bertrandite is just one mineral component of the rock, which is quite rare; most are destroyed in ore crushers before they can reach the jewelry market. Other interesting specimens included rhodonite from Colorado, black jasper and polkadot agate from Oregon, oligoclase from Nevada, coral from Alaska, and glacier stone from Idaho.

These rock buttons are sold individually. Designers or consumers can use them in any combination to create their own custom looks. The buttons can be strung on metal, leather, or other materials to form individualized necklaces and bracelets. Source: GIA @topic:1


Title: Dumortierite-Quartz Rock Presented as Sapphire Abstract: Figure 1. These 5.16 and 2.59 ct specimens, submitted as sapphire and initially thought to be dyed quartzite, were identified as dumortierite-quartz rock. Photo by G. Choudhary.

              The Gem Testing Laboratory of Jaipur, India, received for identification an opaque blue specimen, submitted as sapphire. The 5.16 ct cabochon (figure 1, above) measured 12.59 × 10.28 × 4.71 mm. Examined under a fiber-optic light source, the specimen displayed an uneven blue coloration associated with dyed materials, possibly dyed quartzite.

Gemological testing gave a vague spot RI around 1.55 and a hydrostatic SG of 2.99.The stone fluoresced strong blue to short-wave UV and was inert to long-wave UV. It showed no reaction when viewed with the Chelsea color filter and no distinct absorptions using the desk-model spectroscope, reactions that would preclude the possibility of dyeing. The RI was consistent with quartz, but the SG value ruled out that possibility. Because of the curved surface and opacity of the cabochon, we asked the client to provide a specimen with a flat polish, enabling us to properly study the material. The client also provided a thin slice of the material (figure 15, right), which allowed light to pass through easily. The properties of the slice were similar to those recorded for the cabochon. Two RI readings were obtained while slightly shifting the slice, however. Although the readings were not clear, shadow edges were seen at about 1.54 and 1.68.

Initial microscopic observations of the slice with strong transmitted light suggested blue color concentrations along the boundaries of white to colorless grains, as seen in dyed materials (figure 2, below). Yet the interstitial areas were wider than those of dyed quartzite or any other dyed substance. On further examination of the slice, inhomogeneous blue and white granular texture became evident, where some blue grains were also visible. Reflected light revealed a clear difference between the blue and whitish portions (figure 16, right). The sharp-edged whitish irregular grains, which appear gray in the image, seemed to be embedded in the blue matrix. Also, the white portion had a much duller luster than the blue one. These features suggested that the blue color was indeed natural and that the uneven coloration was not the result of dyeing, but rather a mixture of white and blue materials.

	Figure 2. Uneven blue and colorless areas (left) suggested color concentrations associated with a dyed specimen, but reflected light (right) revealed a clear difference between the blue and whitish portions. The sharp-edged whitish irregular grains (which appear gray in the image) seemed to be embedded in the blue matrix. The white mineral was identified as quartz and the blue mineral as dumortierite. Also note the difference in the luster of two areas, although both minerals have similar hardness. Photomicrographs by G. Choudhary; magnified 32×.
UV-Vis-NIR spectroscopy of the slice in the 200–2000 nm region showed broad absorption bands (figure 3) centered at ~290 and ~610 nm, which are assigned to the Fe2+-Ti4+ charge transfer (see Platonov et al., “Fe2+-Ti4+ charge-transfer in dumortierite,” European Journal of Mineralogy, Vol. 12, No. 3, pp. 521–528). This was confirmed by EDXRF analysis, which detected the presence of Fe and Ti along with Al, Si, Ca, and As. In the DiamondView, the blue portions gave strong blue reactions while the white grains remained inert (figure 4).

	Figure 3. The slice’s UV-Vis-NIR spectrum in the 200–2000 nm region showed broad absorption bands centered at ~290 and ~610 nm, which are assigned to Fe2+-Ti4+ charge transfer and associated with dumortierite.
Raman analysis using a 532 nm laser confirmed the blue and white minerals as dumortierite and quartz, respectively. The blue durmortierite revealed major peaks in the 200–2000 cm–1 region at ~206, 290, 396, 446, 506, 844, 945, and 1068 cm–1, while the white quartz showed major peaks at ~206, 263, 353, 464, 807, 1080, and 1157 cm–1.

These peaks are consistent with those reported for dumortierite and quartz in the RRUFF database. Furthermore, the SG value of 2.99 suggested a composition of approximately 54.64% quartz and 45.36% dumortierite (assuming an SG of 2.65 for pure quartz and 3.40 for dumortierite, while disregarding other accessory minerals).

	Figure 4. DiamondView imaging revealed strong blue fluorescence in the dumortierite portion of the slice, while the quartz grains appeared dark and remained inert.
Identification of this specimen would have been difficult in the absence of Raman analysis, though UV reactions and a vague RI shadow edge offered some clues. For several years dumortierite has been known to occur with quartz as rock and massive forms, but it is not routinely seen in the trade, perhaps due to lack of awareness or because it is being misrepresented, as in this case. The client had no information on the origin of these specimens, which were purchased on the local market, but dumortierite in quartz has been reported from India (R. Webster, Gems, 5th ed., revised by P. G. Read, Butterworth-Heinemann, Oxford, UK, 1994). Source: GIA @topic:2


Title: Summer 2023 G&G Available Now Abstract: The summer issue of G&G is packed with interesting new content! In our three feature articles, read about a newly discovered treatment in spinel, a find of augite in Vietnam, and the origin of mammoth ivory’s brown color. In addition to these articles and our regular quarterly sections, we see the return of Colored Stones Unearthed and finish the issue with a spotlight on fire obsidian.
COLOR MODIFICATION OF SPINEL BY NICKEL DIFFUSION: A NEW TREATMENT
Dr. Michael Jollands and GIA researchers share their study of a new color treatment for natural spinel, which turns lightly colored stones into deeper blue and green hues. Their analysis of a set of faceted spinel submitted as “cobalt diffused” revealed that the gems were actually diffused with nickel. With this treatment likely to become more common in the gem market, the team also suggests criteria for identifying nickel diffusion in blue and green spinel.
GEM-QUALITY AUGITE FROM DONG NAI, VIETNAM
A team led by Le Ngoc Nang reports on a variety of gem-quality augite from Dong Nai, Vietnam. Characterized by intense dark brown or dark green colors when viewed in transmitted light, the augite is classified as magnesium-rich and has potential for use in jewelry and in carvings.
ORIGINS OF COLOR IN BROWN MAMMOTH IVORY
Mammoth ivory is most commonly found with a brown surface color. Zhaoying Huang and coauthors investigate the origin of this brown color by studying mammoth ivory samples’ spectroscopic and mineralogical characteristics, surface morphology, and chemical composition. They determine that formation of iron oxides, manganese oxides, manganese hydroxides, and iron sulfides on the ivory underground resulted in the brown surface color.
LAB NOTES
GIA’s global laboratory staff present their latest findings in the Lab Notes section, including yellow zoning in unusual natural pink diamonds, invisible markings in CVD laboratory-grown diamonds, and an exceptionally large South Sea cultured pearl.
MICRO-WORLD
The Micro-World section, dedicated to the inner world of gemstones, highlights thread-like serpentine inclusions in brown peridot, a globular iron stain and curved lines in yellow sapphire, an interesting metal sulfide inclusion in garnet, and more.
COLORED STONES UNEARTHED
Colored Stones Unearthed returns to examine gem minerals that form in metamorphic environments, such as jade, corundum, tanzanite, and tsavorite garnet. Studying these gems offers gemologists insight into the evolution of tectonic activity that led to their formation.
GEM NEWS INTERNATIONAL
GNI contributors cover a wide variety of topics, ranging from reports on several pearl species to a new treatment used to create phantom structure in opal. The section also includes a roundup of the spring 2023 auction highlights and recaps of the 2023 Sinkankas Symposium and the sustainability panels at the JCK show in Las Vegas.
IN THE SPOTLIGHT
Lastly, we spotlight fire obsidian, a rare volcanic glass found only in the Glass Buttes region of Oregon. Lapidary artist Tom Dodge shares his work revealing a vibrant spectrum of iridescent colors. Source: GIA @topic:1


Title: Sapphire from Montana’s Secondary Deposits, Colombian Emerald Morphology, the 2023 Tucson Shows, and More… Abstract: Welcome to the Spring 2023 issue of Gems & Gemology! A new volume year kicks off with our recap of the Tucson gem shows, where buyers, sellers, and industry professionals from all over the globe converge. And with two major feature articles, our regular sections, and the annual G&G Challenge, this issue is sure to captivate readers.
“The article also details the fascinating history of sapphire mining in these three Montana mining districts, which still hold substantial resources.”
In our lead article, Dr. Aaron Palke and coauthors present their study of the gemological characteristics of sapphire from Montana’s secondary deposits. Using Rock Creek, Missouri River, and Dry Cottonwood Creek samples in a variety of colors, the authors provide typical inclusion scenes and trace element chemistry fingerprints. The article also details the fascinating history of sapphire mining in these three Montana mining districts, which still hold substantial resources.
Next, Dr. Karl Schmetzer and Gérard Martayan investigate the less common morphological and growth phenomena of Colombian emerald samples to understand their growth and post-growth history. Based on their observation of 15 isolated emerald crystals and seven specimens in matrix using optical methods, they offer insight into the different patterns, with a goal of expanding the database of morphological features in Colombian emerald.
Our regular features provide informative snapshots, beginning with Lab Notes. Highlights from the section include a rare example of the purple collector gem anhydrite, a heart-shaped golden South Sea cultured pearl displaying natural shape and color, and the largest sample of synthetic rutile examined at GIA to date. Explore the inner landscapes of gemstones in our Micro-World section, where you’ll see rare cloud inclusions resembling a starry night in diamond, a macroscopic mineral inclusion cluster in a Pakistani aquamarine crystal, a three-phase inclusion in alexandrite, and more. Diamond Reflections returns in this issue, this time exploring plastic deformation in diamond. Our Gem News International section begins with nearly 30 pages covering the 2023 Tucson gem shows, ranging from the latest trends and market updates to noteworthy designs, followed by an opulent photo gallery packed with finds from the shows. The GNI regular features include various pearl discoveries from around the world and a new source of ruby from Liberia.
Finally, test your gemological knowledge of our 2022 feature articles in the annual G&G Challenge, and find out which articles received the Dr. Edward J. Gübelin Most Valuable Article Award.
We hope you enjoy the latest issue of Gems & Gemology! Source: GIA @topic:1


Title: Spring 2023 G&G Available Now Abstract: A variety of topics awaits you in the Spring issue of G&G. With two feature articles, another installment of Diamond Reflections, our report on the 2023 Tucson shows, the annual G&G Challenge quiz, and more, there’s something for everyone inside.
GEMOLOGICAL CHARACTERIZATION OF MONTANA SAPPHIRE FROM THE SECONDARY DEPOSITS AT ROCK CREEK, MISSOURI RIVER, AND DRY COTTONWOOD CREEK
Dr. Aaron Palke and coauthors share their in-depth study of Montana sapphire from secondary deposits at Rock Creek, Missouri River, and Dry Cottonwood Creek. After detailing the fascinating history of sapphire mining and the geology of these three Montana mining districts, the authors cover the gemological characteristics of secondary Montana sapphire, including a comparison to the characteristics of sapphires from Tanzania. Finally, the article chronicles the heat treatment process of five Montana sapphire samples.
MORPHOLOGY OF COLOMBIAN EMERALD: SOME LESS COMMON CASES AND THEIR GROWTH AND DISSOLUTION HISTORY
Dr. Karl Schmetzer and Gérard Martayan investigate the morphological features in Colombian emerald to understand their growth and post-growth history. After studying a collection of 15 isolated emerald crystals and seven specimens in matrix using optical methods, the authors offer insight into the different patterns, including possible relationships to trapiche emeralds and those exhibiting the gota de aceite effect.
LAB NOTES
GIA’s global laboratory staff present their latest findings in the Lab Notes section, including a Libyan Desert glass bangle bracelet, a collection of pearls treated to look antique, and the largest faceted synthetic rutile examined at GIA to date.
MICRO-WORLD
The Micro-World section, dedicated to the inner world of gemstones, highlights a three-phase inclusion in alexandrite, a garnet inclusion resembling a flying insect in diamond, a series of negative crystals arranged in an arrow-like pattern in sapphire, and more.
DIAMOND REFLECTIONS
Diamond Reflections returns in this issue, providing a look at plastic deformation, one of the most prevalent features in natural diamond.
GEM NEWS INTERNATIONAL
Finally, the Gem News International section starts with our coverage of the 2023 Tucson gem shows, including the latest trends, market and mining updates, as well as handcrafted designs and unique specimens from all over the world. The GNI section continues with more noteworthy content, including reports of pearls from the UAE, Bahrain, and Chile and a color study of fancy sapphire from Greenland.
The Spring issue also contains the 2023 Gems & Gemology Challenge quiz. Score 75% or better and you’ll receive a certificate of completion (PDF file); earn a perfect score and your name will be listed in the Fall 2023 issue. Online entries for the Challenge must be submitted by Friday, September 1, 2023. Source: GIA @topic:1


Title: Quarterly Crystal: Columbite(?) in Beryl Abstract: Figure 1. Measuring 26.36 mm in length and weighing 56.00 ct, this Pakistani aquamarine crystal is host to an eye-visible 7.20 mm mineral inclusion cluster. Photo by Annie Haynes.
Those in the gem and mineral community can appreciate the near-perfection of a beautifully crystallized mineral specimen or a well-cut gemstone. But these surfaces are only the exterior, covering a complex, multilayered story within. These internal contents often remain unknown unless we choose to explore below the surface. Somewhat like trees and their rings, minerals and gems form as concentric, typically crystallized layers, recording the developmental details within each layer through changes in temperature, pressure, and chemistry. While some of these growth details are submicroscopic and remain hidden during microscopic observation, other features such as mineral inclusions and encapsulated fluids are waiting to be discovered. In a very real sense, inclusions and their developmental sequencing in their host gems and minerals are descriptions of mineralogical genetics.
Researchers focused specifically on inclusions usually cannot outbid serious gem and mineral collectors for crystals and fashioned gems with interesting internal targets. As a result, many such “gems” end up in private collections, and their inclusions are rarely, if ever, fully documented. This is a tremendous missed opportunity, because inclusions contain geological information that tells a story about themselves and their host.
For this issue’s Quarterly Crystal, we recently had the opportunity to document a well-formed gem-quality, transparent, very light greenish blue terminated hexagonal crystal of aquamarine, with a small amount of light brown matrix at the base and a clearly visible inclusion cluster at the near center (figure 1). The aquamarine was obtained from Muntazir Mehdi of Shad Fine Minerals International in Gilgit-Baltistan, Pakistan. The geographic source was reportedly the Kharguluk mine in Baltistan Province.

Figure 2. None of the analytical techniques at our disposal were able to conclusively identify the mineral making up the 7.20 mm inclusion cluster. The distinctive morphology shown by these inclusions strongly suggests that the cluster is composed of columbite-(Mn) crystals. Photomicrograph by Nathan Renfro; field of view 10.28 mm.
At 56.00 ct with corresponding measurements of 26.36 × 16.09 × 15.02 mm, this aquamarine played host to an easily eye-visible tight cluster of randomly arranged dark reddish brown to black bladed crystals (figure 2) that resembled the mineral columbite-(Mn), Mn2+Nb2O6, as shown by E.J. Gübelin and J.I. Koivula (Photoatlas of Inclusions in Gemstones, Volume 2, Opinio Verlag, Basel, Switzerland, 2005, pp. 263, 319).
Micro-Raman has significantly reduced the time required to instrumentally identify many inclusions. Some inclusion identifications that once took hours can now be made in a matter of minutes using this technique. The Raman instrument can also analyze some subsurface inclusions at depths of more than a millimeter in certain favorable instances, which means inclusions do not need to be exposed to the surface.
After several Raman attempts from different directions, we realized that destructive analysis would be needed to clearly identify the inclusion cluster deep within this stone. Due to the value of this inclusion specimen, we opted to forgo destructive analysis and keep the beryl crystal intact for future gemological exploration. Source: GIA @topic:3


Title: Tucson 2023 Overview Abstract: Figure 1. This ring from Graff features a 3.95 ct pink sapphire and 7.5 carats of diamond in a spiral design. Photo by Robert Weldon; courtesy of Jewelerette Co.
This year’s Tucson shows were well attended, and many vendors were relieved by the strong sales. In fact, the only “complaint” from vendors this year was that for many it was too busy to take even a short break away from their booths. Some vendors reported selling less than in 2022, but still more than in pre-COVID years.
Supply chain issues resulting from lack of output during the pandemic are still being felt. For many sellers demand often exceeded supply, especially for fine-quality colored stones, and prices are increasing to reflect that. With this increase expected to continue, the heavy booth traffic could be due to consumers buying as much as possible at these price points. This corresponds with comments from Nathan Renfro on the GIA show services laboratory, which received a near-record number of submissions this year. As for the trends in materials submitted to the lab, he indicated a typical mix of the major stones: mainly ruby, sapphire, emerald, Paraíba tourmaline, and alexandrite.

Figure 2. Left: “Edison” pearls were available in large sizes and attractive colors. Photo by Si Athena Chen; courtesy of A&B Jewelry. Right: A strand of “Edison” pearls of various colors, in sizes from 14 to 16 mm. Photo by Mimi Travis; courtesy of Yen’s Jewelry & Accessories.

Figure 3. This pin features a 63.92 ct Ethiopian opal with 23.85 carats of conch pearl, 5.88 carats of natural pearl, and 15.85 carats of diamond, set in platinum. Photo by Robert Weldon; courtesy of Pioneer Gems of New York.
At the AGTA GemFair and Gem & Jewelry Exchange (GJX) shows, sapphire, large freshwater pearls from China, and Ethiopian opal were among the eye-catching gems. Sapphire was once again a top seller, with blue and untreated colors doing especially well. Many fancy-color sapphires, including ones in saturated hues such as magenta, were available (Pantone’s Color of the Year for 2023 is Viva Magenta) (figure 1). There were multiple sellers of akoya, Tahitian, and “Edison” pearls in both venues. Most notably, “Edison” pearls were available in much larger sizes and with more saturated colors than in years past (figure 2). Non-nacreous pearls were also featured more prominently. Ethiopian opal, first introduced in Tucson in 2009, was very popular this year. It has climbed from a novelty to a gemstone found in top designer luxury jewels, such as the Zoltan David necklace shown on the cover of this issue and the pin featuring both Ethiopian opal and conch pearls in figure 3. Tourmaline from newly discovered pockets in San Diego County’s Pala District was also on display.

Figure 4. Earrings featuring diamond slices and rose-cut rubies. Photo by Mimi Travis.

Figure 5. “Salt and pepper” diamonds containing eye-visible inclusions. Photo by Jennifer Stone-Sundberg; courtesy of Misfit Diamonds.

Figure 6. An unusual 6.95 ct cushion-cut bicolor alexandrite from Madagascar displaying a color change from yellowish green and reddish brown in daylight (left) to yellowish orange and orangy brown in incandescent illumination (right). Photos by Robert Weldon; courtesy of Bryan Lichtenstein, 3090 Gems, LLC.
The demand for one-of-a-kind gems was apparent in all aspects—cut, color, and even inclusions. Nontraditional cuts such as slices, fantasy cuts, rose cuts, kites, and tablets were readily found in gems ranging from rutilated quartz to diamond (figure 4). Beyond nonstandard cuts, stones with obvious inclusions were very popular. The appeal of these stones centers on their uniqueness. “Salt and pepper” diamonds with multiple eye-visible white, gray, and black inclusions were available loose (figure 5) and in jewelry items throughout the shows. Similarly, nontraditional colors for particular varieties, including color-change stones, pastel colors (such as “mint” tourmaline), teal, and bicolor stones, were trending (figure 6). Strong demand for these nontraditional or one-of-a-kind stones comes from small-scale individual designers with the ability to promote to a wide audience via social media.
In 2020, we reported on the first Ethical Gem Fair in Tucson. This year, suppliers at the fair were pleasantly surprised by the number of large jewelry manufacturers who attended for the first time. The trend toward responsible sourcing, traceability, transparency in practices, and social awareness, which has long been a key differentiator for some jewelers, is clearly becoming more mainstream as customers increasingly demand to know more about the origin and impact of the stones they are purchasing. This year, jewelers at AGTA and GJX also emphasized the importance of providing an environmentally conscious product and the increasing demand from clients for full chain-of-custody information on stones. Similarly, many small-scale designers and buyers were seeking out gems mined in the United States, such as Montana sapphire, Oregon sunstone, and amethyst from the Four Peaks mine in Arizona. They noted high demand for these gems, which seem to satisfy consumer sustainability concerns. In many cases, the younger generation of jewelers has brought a focus on ethical and environmentally sound practices to multigenerational businesses.
We hope you enjoy our coverage of the 2023 Tucson gem shows, where you’ll find striking pieces we saw, the latest trends, mining updates, and more.
The following contributed to this report: Lisa Neely, Mimi Travis, Nathan Renfro, Albert Salvato, and Wim Vertriest.

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Photo Highlights from the 2023 Tucson Shows Source: GIA @topic:11


Title: Rare Double Pseudomorph Ikaite-Calcite-Opal Abstract: Figure 1. The Heart of Australia, a 3,510 ct double pseudomorph ikaite-calcite-opal gem specimen, is considered one of the finest ever unearthed. Courtesy of Graeme Dowton.
At the Pueblo Gem & Mineral Show, Graeme Dowton of Red Earth Opal (White Cliffs, Australia) exhibited rare double pseudomorph ikaite-calcite-opal gem specimens mined from the Naatji Nest mine at White Cliffs in New South Wales, Australia. Ikaite was initially substituted with calcite and then opalized, therefore making these double pseudomorph opals. Also called “pineapple opal” in the market due to the form of their clusters, they are found exclusively in White Cliffs and typically occur within weathering-bleached siltstones and claystones. According to Dowton, no other type of gem-quality opal was found in the same layer where the pineapple opals were mined. During mining, it was noticed that two opals had formed within a few feet of each other but with distinctly different coloration: One displayed a rich spectrum of play-of-color, while the other showed almost no coloration. The 3,510 ct Heart of Australia (figure 1) shows rich play-of-color and is considered one of the finest specimens of this type ever unearthed. In some of Dowton’s samples, the precursor calcite was not fully substituted by silica gel, and white calcite crystals can be observed (figure 2).

Figure 2. The intergrowth of opal and its precursor calcite in pineapple opal. This specimen is 12 × 10 × 8 cm and weighs 690 g. Photo by Si Athena Chen; courtesy of Graeme Dowton.
Ikaite, CaCO3•6H2O, is a rare and metastable hydrated carbonate in sedimentary rocks that has only been identified in environments ranging from –2° to 7°C in nature (M.L. Vickers et al., “The ikaite to calcite transformation: Implications for paleoclimate studies,” Geochimica et Cosmochimica Acta, Vol. 334, 2022, pp. 201–216). The occurrence of ikaite suggests a period of very cold to near-freezing paleoclimate conditions in White Cliffs. At ambient temperatures (10°–30°C), ikaite transforms to more stable carbonate polymorphs such as calcite, aragonite, and/or vaterite. The ikaite and its following pseudomorphs act as paleothermometers (D. Shearman and A. Smith, “Ikaite, the parent mineral of jarrowite-type pseudomorphs,” Proceedings of the Geologists Association, Vol. 96, No. 4, 1985, pp. 305–314). When the host sedimentary rocks were weathered, they released silica into groundwater. This silica-bearing groundwater contacted with calcite, which gradually dissolved and reprecipitated to opal over time (B. Pewkliang et al., “The formation of precious opal: Clues from the opalization of bone,” Canadian Mineralogist, Vol. 46, No. 1, 2008, pp. 139–149). However, the detailed formation mechanism of ikaite-calcite-opal in White Cliffs requires future investigation. Source: GIA @topic:12


Title: Custom Knives by Loren Feldman Abstract: Figure 1. Loren Feldman holds a piece of gem dinosaur bone, displaying the variety of colors and textures he can choose for his knives. Photo by Robert Weldon; courtesy of Loren Feldman.
Some of the most interesting discoveries in Tucson came courtesy of Loren Feldman (Feldman Custom Knives, Gold Canyon, Arizona). His knives are works of art constructed from some of the rarest materials on Earth—and other planets. A visit to Feldman’s booth is a fascinating walk through history that reveals geological treasures such as Tyrannosaurus rex bones, woolly mammoth tusks, and meteorites that fell to the earth millions of years ago.
Remarkably, Feldman has only been making knives for seven years. He describes his introduction to the craft and training as pure luck. Collecting rocks and minerals since he was a young boy, Feldman impressed custom knife maker Robert Stratton with his enthusiasm at the 22nd Street show in Tucson. After a fourth visit to the booth, Stratton generously offered to teach Feldman everything he knew about the craft. At the end of the training, he allocated part of his Tucson booth space to help Feldman get his start in the business. Feldman said that after his apprenticeship, “it took me about two years full-time to consider my work what I considered good. It took me about three years to pay all my bills. And seven years later, it’s the happiest I’ve ever been as far as a profession.”
Feldman’s knife handles are crafted from minerals, gems, and fossilized dinosaur bone. One of his favorites is a knife made of gem dinosaur bone from nine different dinosaurs (shown on the cover of this issue). He explained that only 1/20 of 1% of all dinosaur bone turns into gem, describing it as a miracle of nature because it is only created under very specific conditions. During this process, the dinosaur bone undergoes a transformation that leaves the bone with a beautiful pattern of color and texture (figure 1). Of all the materials he uses, he gets the most excited about gem dinosaur bone because it’s so scarce and highly coveted (figure 2). Feldman also makes his handles from rare gems and minerals from all over the world, such as charoite from Siberia, Ammolite from Alberta, green jade from British Columbia, black jade from Western Australia, dumortierite from Mozambique, lapis lazuli from Afghanistan, labradorite from Madagascar, and agate from Northern Mexico.

Figure 2. Feldman studies a piece of gem dinosaur bone he cut, contemplating how to incorporate it in the knife handle. Photo by Robert Weldon; courtesy of Loren Feldman.
Equally impressive are Feldman’s blades. Made of fine American Damascus steel, the blades are one of three types: carbon, stainless steel, or mosaic. Feldman also crafts blades from iron meteorites that fell to the earth millions of years ago (figure 3). Feldman noted that while rare and expensive, meteorite has been used to make knives throughout history, adding that at least one meteorite blade was found in King Tut’s tomb.

Figure 3. A finished six-inch knife featuring a meteorite blade and gem dinosaur bone handle. Photo by Robert Weldon; courtesy of Loren Feldman.
Feldman purchases some of the material he uses but also does his own exploration and digging. Each summer, he visits a friend’s ranch in Montana to dig for dinosaur bone, and any bone recovered is sent to a lab for identification. He recently found enough T. rex bone to make a knife. Feldman noted that he’s never seen another knife maker incorporate T. rex bone.
Each knife comes with a sheath made of premium leather or exotic skin such as alligator, snake, or elephant—“all legally obtained,” Feldman said. About half of Feldman’s customers also purchase stands, which are crafted with the same rare materials, including dinosaur bone, woolly mammoth tusk, and fine gemstones, and are often chosen to coordinate with the materials in the knife.
When asked what he enjoys most about his business, Feldman revealed that his favorite part is attending the shows and talking with customers. “Doing these events and meeting the collectors, the hunters, the scientists, museum curators, and the professors. I love learning more about the products I sell. Just about everything that I share with my customers, I learned here at this very show.”
For Feldman, business is better than ever. The pandemic has increased the demand for his handmade creations. He explained that customers have been treating themselves during a time when they’ve been deprived of so much. His clientele, which includes collectors, investors, ranchers, hunters, and culinary artists, has kept him busy for the past two years. Source: GIA @topic:7


Title: Hackmanite/Sodalite from Myanmar and Afghanistan Abstract: In recent years, significant amounts of gem-quality sodalite/hackmanite—some unusually transparent—have been produced from the Mogok region of Myanmar and Badakhshan Province in Afghanistan. Samples from both countries varied in color, transparency, UV fluorescence/phosphorescence, tenebrescence, and UV-Vis-NIR spectra. The Burmese material was generally more included and showed weaker fluorescence and phosphorescence than the Afghan samples. EDXRF spectroscopy revealed traces of sulfur in all samples. The tenebrescence of many of the stones from both localities was strong enough for classification as hackmanite. Source: GIA @topic:2


Title: New CVD Material Submitted for Analysis Abstract: Figure 1. These 10 CVD-grown diamonds submitted to the New York laboratory were fairly large (2.24 ct to 5.90 ct) with high color grades (D to F) and excellent clarity (VVS2 to VS1). Photo by Sood Oil (Judy) Chia.
Since the introduction of its new digital Laboratory-Grown Diamond service, GIA has recently seen a vast increase in the number of diamonds grown by chemical vapor deposition (CVD). These are often large and of exceptional clarity. The New York laboratory recently examined a batch of 10 large, high-quality CVD-grown diamonds from a single client, Shanghai Zhengshi Technology. The diamonds ranged from 2.24 ct to 5.90 ct and came in a variety of fancy shapes, as well as the standard round brilliant cut. All of them had high color grades, ranging from D to F, and excellent clarity, with grades between VVS2 and VS1 (figure 1).

Figure 2. PL spectrum showing the 596/597 nm doublet observed in an as-grown CVD diamond.
The diamonds were all identified as type IIa using Fourier-transform infrared (FTIR) spectroscopy, with the 3123 cm–1 peak that is attributed to most as-grown CVD synthetics and the 3017 cm–1 peak that can be found in treated CVD synthetics both notably absent from their spectra. PL spectroscopy using a 514 nm laser revealed SiV (737 nm), NV– (637 nm), and NV0 (575 nm) centers in all of the diamonds. Also observed was the 596/597 nm doublet, a feature commonly seen in as-grown CVD diamond indicating no treatment was applied (figure 2) (S. Odake, “Melee diamonds: Metal defects and treated color,” Fall 2018 G&G, p. 304).

Figure 3. Each CVD-grown diamond showed a strong birefringence pattern displaying many interference colors. The pattern is not disrupted by the presence of pinpoint inclusions in the diamonds. Photomicrographs by A’Dhi Lall and Elina Myagkaya. Field of view 19.27 mm (left) and 1.26 mm (right).

Figure 4. DiamondView imaging revealed homogenous, unbroken dislocations without the distinct banding that is common in CVD-grown diamonds. Images by Elina Myagkaya.
The diamonds showed strong birefringence when viewed under cross-polarized light, exhibiting both low and high interference colors (figure 3). DiamondView imaging revealed mostly blue, purple, or pink fluorescence, with blue-violet dislocations that were clearly observed in all of the diamonds tested. More notable was the absence of the striations commonly seen in CVD diamonds, which indicate start-stop growth and changing growth conditions (figure 4). The absence of striations implies that these diamonds might have been grown in one continuous step—the fact that the dislocations appear to be homogenous and uninterrupted supports this theory.
This group of lab-grown diamonds possessed high clarity and high color for as-grown material, demonstrating the potential for large lab-grown diamonds to make large inroads in the gem diamond market. With continuing improvements to growth technology, lab-grown diamond identification faces many challenges. While large batches of CVD synthetics from different manufacturers have been documented by GIA in the past (e.g., W. Wang et al., “CVD synthetic diamonds from Gemesis Corp.,” Summer 2012 G&G, pp. 80–97), this set offers insight into potential new CVD growth conditions for CVD synthetic diamonds. Source: GIA @topic:4


Title: Update on Rock Creek Sapphire Deposit Abstract: Figure 1. Excavators and a washing plant on Gem Mountain process gravel for sapphire recovery. Photo by Warren Boyd.

Recently, Montana-based Potentate Mining LLC secured approximately 3,000 acres of sapphire-bearing ground covering the famous Rock Creek sapphire district near Philipsburg, Montana. Since the discovery of these sapphire deposits in the 1890s, this is the first time that one company has consolidated such a large land position, encompassing the old alluvial sites as well as the area on the hills in between these old workings (figure 1). Potentate has assembled a team of highly experienced placer miners, geologists, mining engineers, and heavy equipment operators to recover and process the sapphires from this mine.

The Rock Creek district sapphire deposits occur in debris flow, colluvium, and secondary alluvial deposits (figure 2). Although the bedrock for these deposits has not yet been defined, Potentate plans further geological mapping and geophysical surveys in the near future to uncover these sources.

Figure 2. A trench on Gem Mountain showing the sapphire-rich colluvium on the hilltops between the previously worked gulches. Photo by Keith Barron.
To date, the rough sapphires recovered from the bulk sampling pits range in size from 0.25 ct to over 20 ct. Approximately 15% of this rough occurs naturally in marketable colors, including pink, orange, orange-pink, lavender, golden yellow, blue-green and green, and fine blue (figure 3). A substantial percentage of the remaining rough responds very well to heat treatment technologies that improve clarity and turn greenish and grayish rough to desirable colors such as blue, orange, yellow, pink, and parti-color.

Figure 3. A selected assortment of unheated rough sapphires from the Rock Creek deposit weighing from 0.50 to 17 ct. Photo by Warren Boyd.
The high-grade concentration of the sapphires recovered from the various test pits, and the substantial inferred rough sapphire resource on Gem Mountain, indicate that Potentate would be able to provide a long-term, consistent supply of sapphire rough to the global market (figure 4). Potentate would be the only large-volume source for the Rock Creek sapphires. The company is developing a marketing strategy that would provide sustainable supply chain guarantees to their clients. These clients including wholesale gemstone cutters, polishers, and fine jewelry retailers would in turn be able to provide guarantees of origin and the presence (or absence) of any heat treatment to their consumers.

Figure 4. A selection of natural and heat-treated Rock Creek sapphire ranging from 0.50 to 4.70 ct. Photo by Jeff Scovil. Source: GIA @topic:1


Title: Rock Creek Sapphire Mining and Marketing Update Abstract: Figure 1. The newly equipped water clarifier at the West Fork property can nearly fully recycle the water used for mining. Courtesy of Potentate Mining

              Sapphires were discovered in Montana on the West Fork of Rock Creek in 1892. The shiny pebbles were later identified as sapphire and featured at the Paris Exposition in 1900. Four deposits, one primary and three secondary, were discovered and developed across the western portion of the state. Among them, the secondary deposit at Rock Creek has always been the richest and the most productive. It is estimated that this deposit produced about 65.8 tons of rough sapphire until 2014, which is about 90% of the total sapphire production of all four deposits.

Since 2011, Potentate Mining has been gradually developing and expanding its sapphire mining concession in the Rock Creek area through a series of land purchases. With the latest deal done in 2020, the company now possesses more than 3,500 acres of private property over the sapphire-bearing land.

In addition to the expansion, in 2019, the washing plant moved from Eureka Gulch to a new location at the West Fork property, where mining is done on the top of the hill (T. Hsu et al., “Big Sky Country sapphire: Visiting Montana’s alluvial deposits,” Summer 2017 G&G, pp. 215–227). This new washing plant includes a water clarifier that, although not required by state mining regulations, can recycle nearly 80–90% of the water used for mining (figure 1). Before the wastewater reaches the clarifier, it goes through a centrifugal concentrator to recover fine gold and very small sapphires (figure 2). This washing plant is also extremely close to the mining site, which dramatically increases the efficiency of ore processing.

Figure 2. Left: Potentate Mining marketing director Warren Boyd (on the right), mine geologist and manager John Rae (in the back), and a client gather around the centrifugal concentrator. Right: The concentrator extracts fine gold and very small sapphire crystals from the water coming out of the jig before it enters the clarifier. Courtesy of Potentate Mining.
Potentate Mining sells rough and faceted sapphire at the Tucson and JCK shows to retailers and jewelry designers. Since 2016, it also offers natural, heat-treated rough sapphire by lots to clients in North America, India, Sri Lanka, and Thailand. Most of these clients are cutting operations. The COVID-19 pandemic reduced the number of staff working onsite at the mine in 2020, but the production was not dramatically affected. Due to travel restrictions, stone viewing became extremely difficult. According to marketing director Warren Boyd, lots have been shipped to clients since the start of the pandemic. While viewing ahead of receiving lots was impossible, the company expected and has accommodated a certain amount of returns from clients. With Potentate adapting to the unexpected, 2020 sales were about the same as the year before. Source: GIA @topic:1


Title: Winter 2022 G&G Available Now Abstract: The Winter issue features three studies on identifying treatments in colored gemstones—ruby, feldspar, and turquoise—and introduces us to an inspirational artist and pioneer in the jewelry industry. In addition to the four feature articles and our quarterly sections, we see the return of Colored Stones Unearthed.
A CANARY IN THE RUBY MINE: LOW-TEMPERATURE HEAT TREATMENT EXPERIMENTS ON BURMESE RUBY
E. Billie Hughes and Wim Vertriest conduct low-temperature heating experiments on Burmese ruby. The appearance of inclusions at each heating step, coupled with spectroscopic analysis, provides evidence of this treatment. Particular solid inclusions proved sensitive to low-temperature heating.
FLUORESCENCE CHARACTERISTICS OF TWO COPPER-DIFFUSED PLAGIOCLASE FELDSPARS: LABRADORITE AND ANDESINE
For this study, Qingchao Zhou and fellow researchers treated colorless labradorite and light yellow andesine with copper diffusion to mimic the color of natural labradorite sunstone. They discovered that fluorescence emission characteristics under 320 nm excitation can potentially help identify copper diffusion treatment in a material that has been a subject of controversy for decades.
COMPOSITION AND SPECTRAL CHARACTERISTICS OF PORCELAIN-TREATED TURQUOISE
A team led by Liying Huang uses a combination of low specific gravity, strong luster, high silica content, and surface features to effectively identify the novel “porcelain” treatment technique. This treatment method improves the luster and color of low- to medium-quality turquoise to meet the demand for scarcer high-quality natural turquoise in the Chinese market.
NEVER STOP INNOVATING: GEM ARTIST CHI HUYNH
Tao Hsu and coauthors visit Chi Huynh, founder and owner of Galatea: Jewelry by Artist, who shares his experiences and passion for jewelry-making innovations. Carved pearls, gem bead cultured pearls, and two-way shape-memory jewelry are but a few of the groundbreaking jewelry design concepts he employs in his finished pieces.
LAB NOTES
GIA’s global laboratory staff present their latest findings in the Lab Notes section, including a unique chrysoberyl displaying four-rayed asterism, the largest cat’s-eye emerald examined by GIA to date, and the identification of two non-nacreous bead cultured pearls from Pinctada margaritifera.
MICRO-WORLD
The Micro-World section, dedicated to the inner world of gemstones, features unusual “horsetail” and columnar inclusions in demantoid, a bluish green omphacite crystal in colored diamond, and aegirine inclusions in poudretteite from a new deposit in Mogok.
COLORED STONES UNEARTHED
Colored Stones Unearthed returns to examine gem minerals that form in magmatic environments, such as diamond, garnet, spinel, and corundum. Through these gems, gemologists gain insights into the generation of magmas within the earth, their transport to the surface, and modes of volcanic processes after eruption.
GEM NEWS INTERNATIONAL
Finally, GNI’s global contributors report on a variety of topics, including an extremely rare hellandite inclusion in ruby from Mogok; the identification of natural, reconstructed, and imitation Burmese root amber; and a roundup of the fall 2022 auction highlights, which had several surprising twists. Source: GIA @topic:13


Title: Discovery of Color-Change Chrome Grossular Garnets from Ethiopia Abstract: Figure 1. Left: Three rough garnets (left to right, stones 2, 3, and 4) and one faceted garnet photographed in an LED light source with 6000K color temperature (a daylight-equivalent light simulator). Right: The same stones photographed in an LED light source with 3100K color temperature (an incandescent light simulator). The 2.705 ct faceted stone measures 8.08 × 7.18 × 5.49 mm. Photos by Kevin Schumacher.
Ethiopia has become a significant producer of opal, sapphire, and emerald in recent years. In addition, reports of gem-quality green garnets have started to emerge (B. Williams et al., “Tsavorite reportedly from Ethiopia,” Journal of Gemmology, Vol. 35, No. 8, 2017, pp. 702–704).
Todd Wacks (Tucson Todd’s Gems, Tucson, Arizona, and Vista, California) recently submitted three rough and one faceted garnet (figure 1, stones 1, 2, 3, and 4) to GIA in Carlsbad for scientific examination. He purchased the garnets from Inna Gem, which reported that the garnet mine is located near the town of Wbi and the new Dubuluk emerald deposit (Spring 2017 GNI, pp. 114–116). The stones showed obvious color change from yellow-green under daylight-equivalent lighting to orange-brown under incandescent illumination. This is similar to the color-change behavior reported for some color-change garnets from Sri Lanka (Spring 2017 GNI, pp. 137–138).
Standard gemological testing revealed a refractive index (RI) of 1.740 on the faceted stone. Hydrostatic specific gravity (SG) of all garnets in this study ranged from 3.62 to 3.68. Fluorescence was inert to long-wave and short-wave UV light. Rotating the stones 360° between a pair of crossed polarizing filters revealed an anomalous double refraction. Using a handheld spectroscope, faint absorption bands at 480–490 and 570–590 nm were observed. Microscopic examination showed fingerprints composed of two-phase inclusions, iron-stained and cloudy fractures, long thin etch channels, unidentified transparent crystals, and zoned greenish brownish yellow areas. These properties are consistent with grossular (grossular-andradite) garnets (I. Adamo et al., “Tsavorite and other grossulars from Itrafo, Madagascar,” Fall 2012 G&G, pp. 178–187; M.L. Johnson et al., “Gem-quality grossular-andradite: A new garnet from Mali,” Fall 1995 G&G, pp. 152–166).
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analyses were performed to obtain the chemical composition of these garnets using a Thermo Fisher iCAP Qc ICP-MS coupled with an ESL NWR213 nm laser ablation unit. USGS glass standards GSD-1G and GSE-1G and NIST glass standard 610 were used as external standards. 29Si was used as an internal standard. The analyses were performed in the same region where spectroscopic data was collected for stones 3, 4 (Ethiopian garnets), 5 (non-Ethiopian tsavorite), and 6 (non-Ethiopian demantoid) (see supplementary table S1).

Figure 2. The calculated visible absorption spectra (corrected for reflection loss) of garnets 3, 4, 5, and 6 with various path lengths. Transmission window A is centered at 545 nm. Transmission window B is between 620 and 650 nm; transmission window C is centered at 520 nm. In Ethiopian grossular stones 3 and 4, the absorption bands at 431 and 599 nm are caused by Cr3+. In stone 5 (non-Ethiopian tsavorite) the absorption bands at 428 and 611 nm are caused by V3+. In stone 6 (non-Ethiopian demantoid) the absorption bands at 431 and 627 nm are caused by Cr3+ (Adamo et al., 2009). The human eye is not color sensitive above 650 nm or below 420 nm wavelength (gray color zoning in the graph). The transmission in these ranges cannot contribute to the color seen. Please note that the y-axis units are in true absorbance and not absorbance coefficients.
The Ethiopian garnets are predominantly composed of 87.24–91.60% grossular, 6.03–8.19% andradite, 1.04–2.80% spessartine, 1.29–0.55% uvarovite, 0.71–0.82% pyrope, and 0.03–0.05% goldmanite (again, see stones 1–4 at the link provided above). The dominant chromophore is Cr3+ at about 0.19–0.43 wt.%, with an almost negligible contribution from V3+. This contrasts significantly with most tsavorite grossular garnets, whose color is dominantly derived from V3+ with a lesser contribution from Cr3+ (Adamo et al., 2012).

Figure 3. The color panels of four garnets (stones 3, 4, 5, and 6) under CIE A (incandescent) and CIE D65 (daylight-equivalent) illumination are quantitatively reproduced. The garnets’ colors are shown at different light path lengths (defined by stone thickness). For each sample, the top and bottom rows represent the color under incandescent light (A) and daylight-equivalent light (D65), respectively. For calculation methods, please see Sun et al. (2017).
UV-Vis-NIR spectra (figure 2) were collected and corrected for reflection loss. These spectra were then used to quantitatively calculate the color of the garnets at a wide range of path lengths and under different lighting conditions. In addition to two of the Ethiopian grossular garnets, UV-Vis spectra were also collected on the non-Ethiopian tsavorite (stone 5) and the non-Ethiopian demantoid (stone 6) for comparison. The chemistry of stones 5 and 6 is also reported; see the supplementary table S1.

The calculated color panels of stones 3–6 under daylight-equivalent lighting (CIE D65 illumination) and incandescent light (CIE A illumination) are shown in figure 3, which shows the possible colors these four garnets would exhibit with different path lengths (defined by stone thickness) and the approximate corresponding carat weight of a well-proportioned round brilliant (for details of this calculation, see Z. Sun et al., “Vanadium- and chromium-bearing pink pyrope garnet: Characterization and quantitative colorimetric analysis,” Winter 2015 G&G, pp. 348–369). Ethiopian grossular stone 4 showed a stronger color change and a higher chromium component than Ethiopian grossular stone 3. Stone 6 showed a more yellowish green than stone 5 due to the demantoid’s higher Fe component, which absorbs more blue light than in tsavorite (again, see figure 2).

Figure 4. In the CIELAB 1976 color circle, the color of stone 4 changes from yellow-green under CIE D65 illumination to yellow-orange under CIE A illumination, with a hue angle difference of 16.68˚ and a chroma difference of 7.40. The color of stone 3 changes from yellow-green under CIE D65 illumination to yellow-orange under CIE A illumination, with a hue angle difference of 15.94˚ and a chroma difference of 3.74. Stone 5 (tsavorite) has no color change in D65 and A visually. The hue angle difference is 0.48˚, and the chroma difference is 21.73. Stone 6 (demantoid) has no color change in D65 and A visually. The hue angle difference is 1.63˚, and the chroma difference is 20.54.
One way to judge the quality of a color-change stone is to plot the color panel pair in the CIE 1976 color circle. Good color-change pairings show a large hue angle difference, a small chroma difference, and large chroma values (Z. Sun et al., “How to facet gem-quality chrysoberyl: Clues from the relationship between color and pleochroism, with spectroscopic analysis and colorimetric parameters,” American Mineralogist, Vol. 102, No. 8, 2017, pp. 1747–1758). The color coordinates of the four stones in daylight-equivalent (D65) and incandescent (A) illumination were plotted in the CIE 1976 color circle (figure 4). Ethiopian grossular stone 4 had the largest hue angle difference among the four stones and a relatively small chroma difference. The non-Ethiopian tsavorite and demantoid both had a very small hue angle difference that was close to zero but with large chroma difference.
One interesting observation is that the Cr3+ absorption band shifted significantly from 627 in demantoid (stone 6) to 599 in the Ethiopian grossulars (stones 3 and 4; all stone samples contained little V). This shift opens a transmission window B in the red region shown in figure 2. To our knowledge, color-change behavior has not been reported in tsavorite or demantoid. This is because the absorption bands of V3+ at the 610 region in tsavorites (green grossular) or of Cr3+ at the 627 nm region are dominated by Cr3+ in demantoids and prevent the transmission of red light in these stones. In other words, there is no transmission window in the red for tsavorite or demantoid. However, these Ethiopian grossulars have little V3+, and the Cr3+ absorption is shifted away from the red region, which allows for significant transmission of red light through these stones. This creates a transmission window that produces significantly different color for the Ethiopian grossular in incandescent illumination versus daylight. To the authors’ knowledge this was the first group of color-change gem-quality chrome grossular garnet reported. Source: GIA @topic:3


Title: Fall 2022 G&G Available Now Abstract: Get ready to uncover a wide range of topics in the Fall issue, from the challenges of determining the geographic origin of diamond to the use of gem materials as pigments in works of art. In addition to the four feature articles and our quarterly sections, we see the return of Diamond Reflections and the 2022 Gems & Gemology Challenge results.
METHODS AND CHALLENGES OF ESTABLISHING THE GEOGRAPHIC ORIGIN OF DIAMONDS
Diamond origin is a trending topic among consumers and the trade, as consumers seek to know the origin and the impact of purchased goods. The mounting push toward global sustainability has prompted direct efforts to use measurable characteristics to compare diamonds from different localities. The lead article by Evan Smith and coauthors discusses the recent methods and challenges associated with determining the geographic origin of diamonds and concludes that retaining origin information from the time of mining is the only definitive means of establishing provenance.
SAPPHIRE BENEATH THE RICH BLACK SOIL OF MULING, NORTHEASTERN CHINA
Yimiao Liu and Ren Lu characterize the gemological properties, chemical composition, and provenance-related features of sapphire found in Muling, northeastern China, comparing them against samples from other well-known corundum sources worldwide. Their research provides preliminary data to aid in the origin determination of this underexplored sapphire resource.
GEMS ON CANVAS: PIGMENTS HISTORICALLY SOURCED FROM GEM MATERIALS
Pigments derived from gem materials have been utilized for centuries, from ancient cave drawings to classical and modern works of art. These artistic creations reveal the evolution of the human experience and the progression of anthropological and chemical studies. In this article, Britni LeCroy examines the correlation between the evolution of gem pigment technology and historical art movements.
COLOR MECHANISM AND SPECTROSCOPIC THERMAL VARIATION OF PINK SPINEL REPORTEDLY FROM KUH-I-LAL, TAJIKISTAN
A team led by Yicen Liu uses spectroscopy and chemical analysis to study the color mechanism of pink spinel reportedly from the Kuh-i-Lal deposit in Tajikistan. When heated to a series of temperatures, the spinel samples showed that a combination of spectroscopic thermal variation characteristics causes their pink color.
LAB NOTES
GIA’s global laboratory staff present their latest findings in the Lab Notes section, including an exceptionally rare 1.21 ct Fancy orangy red diamond, a star sapphire from the legendary Kashmir deposit, and a synthetic moissanite carved to resemble a natural rough diamond.
MICRO-WORLD
The Micro-World section, dedicated to the inner world of gemstones, features an unusual bright purple fluid in rock crystal quartz, a partially exposed orange rutile crystal in a color-change diamond, and an eye-catching cluster of zircon needles in a stellate formation in Paraíba tourmaline.
DIAMOND REFLECTIONS
Diamond Reflections returns to examine the fluid droplets trapped within diamond during growth in the earth’s mantle. These liquids reflect the various natural processes that occur during diamond formation and provide scientists with a window into the great depths of our planet.
GEM NEWS INTERNATIONAL
Finally, GNI contributors report on saltwater cultured pearls containing non-traditional “box bead” nuclei fashioned from shell, a type of quartz featuring multiple color zones with oriented inclusions, an update on the current state of Mozambique’s ruby mines, and the first-ever Turquoise United conference. Source: GIA @topic:7


Title: Natural and Synthetic Rubies on the Basis of Trace-Element Chemistry Abstract: Natural and synthetic gem rubies can be separated on the basis of their trace-element chemistry as determined by energy-dispersive X-ray fluorescence (EDXRF) spectrometry. This method is especially important for rubies that do not have diagnostic inclusions or growth features, since such stones are difficult to identify using traditional gem testing methods. The results of this study indicate that the presence of nickel, molybdenum, lanthanum, tungsten, platinum, lead, or bismuth proves synthetic origin, but these elements were not detectable in most of the synthetic rubies tested. Alternatively, the concentrations of titanium, vanadium, iron, and gallium––considered together, as a trace-element “signature”––provide a means for separating nearly all synthetic from natural rubies. EDXRF can also help identify the geologic environment in which a ruby formed, and thus imply a geographic origin. Source: GIA @topic:1


Title: Quarterly Crystal: Wurtzite Phantom in Quartz Abstract: Figure 1. Measuring 86.38 mm and weighing 1,140 ct, this quartz crystal from British Columbia contains a three-sided phantom composed of an abundance of opaque black wurtzite inclusions. Photo by Robison McMurtry.
Transparent colorless rock crystal quartz is a strong, durable mineral that makes a favorable host for a wide variety of inclusions (see the three-volume Photoatlas of Inclusions in Gemstones for examples). The geographic source of the crystal pictured in figure 1 is British Columbia, Canada. At 1,140 ct and 86.38 mm in length, this large example of rock crystal plays host to several near-surface opaque black hexagonal to trigonal crystals as large as 5.0 mm.
As shown in figure 2, the micromorphology of the numerous inclusions, forming a three-sided phantom, suggests that they might be the zinc iron sulfide wurtzite. Laser Raman microspectrometry confirmed the identification of the inclusions as wurtzite. The euhedral inclusions were situated in the quartz crystal in the form of directional phantoms that developed through the directional deposition of the wurtzite on three consecutive surfaces of the quartz, which then continued to grow, enveloping the wurtzite as inclusion planes tracing the form of the original quartz host. From what we can determine, this is the first time that wurtzite has been found as an inclusion in any gem material. Because of wurtzite’s relationship to sphalerite, some inclusions previously identified as sphalerite may actually be wurtzite.

Figure 2. The crystals in this phantom plane in quartz were identified by Raman analysis as wurtzite. Photomicrograph by Nathan Renfro; field of view 19.2 mm. Source: GIA @topic:2