Publication Year: - Title: Sapphire Series Part 3: Modern Synthetic Sapphire Applications Abstract: Previously we introduced sapphire as a gemstone and as a major industrial material that spurred the advancement of many synthetic crystal growth techniques. Synthetic sapphire is commonplace in our everyday lives, as its desirable properties—optical, mechanical, thermal, chemical, and structural—have yielded an array of fascinating applications.

	Figure 1. For the past 25 years, titanium-doped synthetic sapphire crystals for high-
	power lasers have been grown using the heat exchanger method. Courtesy of GT
	Advanced Technologies.
A turning point for synthetic sapphire was the invention of the laser in 1960. Theodore Maiman, using a Verneuil-grown ruby crystal fashioned into a rod, demonstrated the first optical laser. The quality of ruby from flame-fusion growth was inadequate for commercial lasers, prompting the synthesis of sapphire using the Czochralski technique. To this day, laser crystals of a variety of compositions are still grown this way. Ruby crystals, traditionally grown for military range finders and cosmetics applications such as tattoo and hair removal, have largely been replaced by other laser materials. Ruby lasers are now mostly used for producing holographic images and drilling small holes in diamond.

Another significant laser crystal is titanium sapphire, often produced by the Czochralski technique or the heat exchanger method (figure 1). Titanium sapphire lasers, with their ability to produce extremely high-energy and ultra-short pulses (pico-, femto-, or even atto-second in duration), have been instrumental in advancing fundamental research and may hold the key to realizing nuclear fusion energy in the future.

	Figure 2. Sapphire windows are widely used in the aerospace industry. Courtesy of GT
	Advanced Technologies.
Once the ability to grow large chromium-doped ruby crystals was established, scientists began developing undoped synthetic sapphire (generally called “white sapphire” or “leucosapphire”) as a durable and highly transparent material. The 1960s saw the advent of low-defect crystals with high chemical purity used in protective laser coverings for the military, aerospace windows (figure 2), bulletproof armor, and various scratch-resistant surfaces. Sapphire, with its desirable insulation and structural properties, was a suitable substrate material for single-crystal semiconductors such as silicon (1963) and gallium nitride (1969). This opened up even more market opportunities, including faster and more energy-efficient circuitry, as in the Hewlett-Packard 41 series calculators developed in the 1970s. The technology also permitted shorter-wavelength light emitting diodes (LEDs) in blue, ultraviolet, and white. Sapphire substrates have grown considerably larger, to 10 inches in diameter (figure 3). Consumer applications of synthetic white sapphire eventually followed.

	Figure 3. Monocrystal’s 10-inch sapphire substrate is shown next to a 2-inch sapphire
	substrate. Courtesy of Monocrystal
We’ve all heard the familiar “beep” at the checkout counter when merchandise is slid across the scanner window next to the cash register. The top layer of that window is made of a very thin piece of sapphire, which keeps the glass free of scratches, allowing countless items to be dragged across it without the need for replacement. First developed in 1978 (figure 4), this application is now seen in retail outlets worldwide. Sapphire windows can also be used to protect biometric fingerprint sensors. There is speculation that smartphone companies may be interested in this technology, and that’s just the beginning of that industry’s synthetic sapphire possibilities.

	Figure 4. This photo shows the very first sapphire point-of-sale window prototype. Courtesy of Frank Bruni. To read more about this prototype, visit http://frankbruni.com/uncategorized/the-birth-of-the-sapphire-pos-terminal-window.
Sapphire has been used as a covering for cellphone camera lenses, and it is also being tested by smartphone and electronic tablet manufacturers for shatter-proof display screens (figure 5). Some very high-end smartphones already have sapphire touchscreens. If every smartphone built next year had a sapphire screen, approximately one billion finished sapphire screens would need to be produced. Consumer demand for a scratch- and crack-free screen is high, and various market players and industry analysts have found a consumer willingness to pay an additional $30 to $50 for this feature. Even so, current synthetic sapphire capacity may not be able to meet the demand.

	Figure 5. Blocks of synthetic sapphire were used to produce these smartphone display screens. Courtesy of GT Advanced Technologies.
Sapphire substrates are being used to produce the next generation of ambient lighting, white LEDs. The white LED is actually a blue LED (figure 6) coated with a yellow-emitting phosphor, a combination that produces white light. The future is bright for LED lighting as the world strives to be more energy efficient and less reliant on toxic elements such as mercury. The demand for substrate sapphire is very large—in the millions per year and growing—and there is competition for resources among manufacturers of synthetic sapphire for various applications.

	Figure 6. Blue, ultraviolet, and white LEDs are commonly grown on synthetic sapphire
	substrates. White LEDs are created by applying a phosphorescent coating such as
	cerium yttrium aluminum garnet to blue LEDs. Courtesy of GT Advanced Technologies.
So where does gemology fit into this? Sapphire occupies a sizeable percentage of the synthetic gemstone market. But even as demand for synthetic gem corundum increases, the portion of industrially grown sapphire crystals used as gem materials is shrinking. With technical applications for sapphire on the rise, the synthetic gem industry will continue to feel the effects in product quality, supply, and pricing—topics that will be further explored in the fourth and final installment of this series. @chapter:12


Publication Year: 2014 Title: Large Oolitic Opal Block Abstract: Figure 1. This exceptionally large 1.43 kg block of opal, which measures 12.8 × 10.1 × 5.8 cm, is rare not only for its size but also its oolitic texture. Photo by C. D. Mengason/GIA, courtesy of Tibor Shelley/Opals by GMT.

              Longtime opal dealer Tibor Shelley (Opals by GMT in Adelaide, Australia) recently brought a large 1.43 kg block of opal (figure 1) to GIA’s Carlsbad laboratory for examination. Mr. Shelley said he purchased it from a miner at the Andamooka opal fields in Australia more than 40 years ago. Since then, it has remained in his private collection. The RI measured on the polished face of this sawn and partially polished block was 1.45, consistent with opal.

	Figure 2. Numerous brown spheres scattered throughout precious opal were seen in this very large block of oolitic opal from Andamooka, Australia. Photomicrograph by Nathan Renfro, courtesy of Tibor Shelley/Opals by GMT; field of view 17 mm.
Upon initial observation, the semi-translucent to opaque opal appeared similar to typical matrix-type opal from Andamooka that is routinely treated black. Microscopic examination, however, revealed an interesting and unique texture rarely seen in Andamooka opal. The stone was composed of numerous dark spherical inclusions, known as “ooids,” with precious opal filling in the pore spaces between the spheres (figure 2). This type of opal has been previously reported (see Summer 1982 Lab Notes, p. 104; Winter 1984 Lab Notes, p. 229; and Spring 1986 Lab Notes, p. 50), but this example is especially rare due to its large size. Although an example of treated black oolitic opal has also been previously reported (Spring 1983 Lab Notes, p. 46), microscopic examination revealed that the overall gray bodycolor of this extremely large opal was due to the high density of dark ooids scattered throughout the block. There were also some light brown patches that appeared to be a sandstone type of matrix, as well as numerous veins and pockets of precious opal that did not contain ooids.

This unusual piece of natural-color oolitic opal is the largest of its type that GIA has examined to date. @chapter:39


Publication Year: 2000 Title: New Filling Material for Diamonds from Oved Diamond Company: A Preliminary Study Abstract: Diamonds filled with a new glass formulation (XL-21) are being marketed by the Oved Diamond Company. These diamonds are readily identifiable as treated by the intense flash-effect colors seen with magnification. Durability testing on a small number of these treated diamonds indicates that this filler material is more stable to conditions of normal jewelry repair, such as direct heating with a torch, than the filler material produced by the Goldman Oved Company a decade ago. Nevertheless, some damage to the filler was observed in half the new Oved diamonds that were subjected to a standard prong retipping. @chapter:35


Publication Year: 2015 Title: International Diamond School Abstract: View Gallery

	International Diamond School
In late January 2015, nearly 100 scientists gathered in the northern Italian town of Brixen to attend the Second International Diamond School (IDS). The program, titled “The Nature of Diamonds and Their Use in Earth’s Study,” was designed so that attendees from varied educational and professional levels could learn from leaders in the field of natural diamond research.

The school successfully blended student and professional perspectives, as well as the cross-disciplinary nature of the participants and speakers. Over four days, IDS attendees from a wide range of backgrounds—including experimental researchers, petrologists, mineralogists, crystallographers, isotope geochemists, and diamond industry experts—were treated to a wide scope of lectures and workshops. Presentations provided insight into diamond exploration, advanced research-level analysis, diamond morphology, inclusion chemistry, and geologic occurrences.

George H. Read (Shore Gold Inc., Vancouver) presented a recent history of diamond exploration, culminating with his company’s new Canadian diamond mine: Star-Orion in Saskatchewan, a $2.5 billion project. He provided context on production history, sources, and trading centers. He outlined future diamond mining projects in Botswana, Canada, Lesotho, and India, concluding that the small number of viable projects might signify a shortfall in rough supply. The complexity and financial risks involved with bringing new diamond mines online was made evident.

Bruce Kjarsgaard (Geological Survey of Canada, Ottawa) reviewed kimberlite eruptive models based on 1970s and 1980s research in South Africa. He explained the revision of these models after new kimberlite discoveries in the 2000s in Canada’s Slave craton. He defined kimberlite as a strongly homogenized and “mixed-up” hybrid rock, representing a blend of crystallization out of the magma with country rock, that is often highly variable from place to place. In a second presentation Kjarsgaard examined the major techniques used for exploration for diamondiferous kimberlites, focusing on the Canadian experience and its applicability to glaciated shield areas such as Canada, Russia, the northern United States, and Finland. These techniques have been remarkably successful, partly because of the solid scientific research behind them.

Jeff Harris (University of Glasgow, UK) reviewed the characteristics of lithospheric diamonds based on his experience as a De Beers research director and his access to an unparalleled proportion of run-of-mine diamonds. He showed how different pipes produce distinct diamond size ranges and morphologies. He covered the age relationships between inclusions and host diamond, inclusion chemistry, formation pressures and temperatures, fluid inclusion chemistry, and the abundance of different carbon and nitrogen isotopes in diamond.

Michael Walter (University of Bristol, UK) discussed the super-deep carbon geodynamics of Earth’s mantle along with information provided by analysis of lower-mantle fluids found as inclusions in “superdeep” (sublithospheric) diamonds from Brazil’s Juina field. He explained how new thinking over the past five to six years has provided a model for diamond formation by subduction of carbonate-bearing hydrated oceanic crust in the transition zone of the mantle at depths of 440 to 600 km.

Paolo Nimis (University of Padua, Italy) discussed thermobarometry, a technique that uses mineral phase diagrams to discover the original formation conditions (pressure, temperature, and therefore depth) of rocks in the mantle. He also related the possibility of applying similar techniques to inclusions in diamonds to help determine their formation conditions. His talk explored the accuracy and precision of the different thermobarometers and where future improvements are likely to occur.

Ross Angel (University of Padua) discussed elastic barometry for inclusions in diamonds. This new field uses Raman shift or X-ray diffraction (lattice distortion) to measure decompression effects on the surrounding diamond crystal caused by inclusions formed at high pressure to estimate pressure of diamond formation.

Fabrizio Nestola (University of Padua) explained the advanced X-ray diffraction methods used in their laboratory, which permit very rapid crystal orientation and data collection. This work has shown that some olivine inclusions cannot be syngenetic, as they share no preferred orientation with the host diamond.

Graham Pearson (University of Alberta, Canada) overviewed the petrology and geochemistry of cratonic mantle roots. He explained the effects of melt depletion (removal of clinopyroxene and orthopyroxene) to produce very magnesium-rich melts in the sub-continental mantle, which removes rhenium (Re) to “freeze in” the osmium (Os) isotopic system to allow radiometric dating. This gives very different mean Re/Os model ages for “on-craton” (2.5 billion years) and “off-craton” (2.0 billion) mantle xenoliths (potential diamond host rocks) for the Kaapvaal craton, which underlies southern Africa.

Steven Shirey (Carnegie Institution of Washington) reviewed the topic of age-dating diamonds, beginning with work in the 1980s using rare-earth element ratios in silicate mineral inclusions within the diamonds. He covered rhenium/osmium dating techniques devised in the late 1990s and perfected in the 2000s, finishing with recent Re/Os dating work on zoned diamonds from Yakutia, which showed two-billion-year-old cores surrounded by younger rims of one billion years.

Oded Navon (Hebrew University of Jerusalem) presented on silicic and low-magnesium carbonatitic fluids in fibrous diamonds and their relationship to fluids in gem-quality diamonds. He explained how new work on inclusions along the twin planes of otherwise gem-quality diamonds—macles—revealed fluids of very similar compositions. One can generalize from previous studies of fibrous diamond that most diamonds form under similar growth conditions most of the time.

Thomas Deining (WITec Instruments Corp., Ulm, Germany) introduced WITec’s confocal Raman spectrometer system and described its ability to map three-dimensional fields of features at very high resolution. This instrument is ideally suited to looking into diamond, and his talk set the stage for the Raman workshops the following day.

Maya Kopylova (University of British Columbia) discussed fluid inclusions and volatiles in monocrystalline, octahedral diamonds, with a focus on nitrogen (N2) and carbon dioxide (CO2). She related this new work to previous studies on fibrous diamonds, showing it has wider relevance than previously thought.

Wuyi Wang (GIA, New York) covered diamond treatment and synthesis. He introduced the various causes of color in natural diamonds and explained how combinations of irradiation and high-pressure, high-temperature (HPHT) treatment might alter or remove color. He also reviewed improvements in synthetic diamond size and quality due to advances in HPHT and chemical vapor deposition (CVD) synthesis technology.

Frank Brenker (Goethe University, Frankfurt) outlined the latest findings on ultra-high pressure mineral phases in diamonds. Much of this work is nanostructural in nature and requires removing exceptionally thin wafers of diamond by focused ion beam lithography, a technique borrowed from the electronics industry. Brenker dealt specifically with the idea that some of the inclusion minerals thought to have grown in the lower mantle (e.g., Mg perovskite and ferropericlase) might actually have formed at the shallower depths of the mantle transition zone or even the upper mantle.

Dan Frost (University of Bayreuth, Germany) presented on the experimental petrology of the mantle, using state-of-the-art multi-anvil presses capable of achieving pressures of 250,000 bar at 1,800°C. This work demonstrates the possibility that at certain temperatures and pressures, a system may exist where carbon dioxide (CO2) and methane (CH4) produce carbon (C) plus water (H2O). He presented this as a new model for diamond formation in the deep mantle.

Pierre Cartigny (Institut de Physique du Globe de Paris) showed how carbon and nitrogen isotopes are used to characterize the fluid sources and fractionations that can occur with diamond growth. One of his long-standing conclusions is that even though subduction of C and N can occur and is thought to be a major process for introducing fluids into the mantle, the signatures of subduction are not as clear as one would expect. The possible isotopic changes that can occur between the diamond and its host fluid during diamond growth need much further study.

Andy Davy (Rio Tinto Plc., Bristol, UK) drew upon his experience as a consulting geologist to discuss the role of engineers and natural diamond scientists in evaluating diamond deposits. His talk covered the exploration and evaluation of prospective deposits, improvements in recovery methods to prevent diamond breakage, and assessing the performance of deposits through time. He left the audience with a realistic picture of the complications in establishing diamond grade, price, and hence the viability of any given diamond project. He further showed how exceedingly rare good diamond-producing kimberlites are.

The school was a fantastic opportunity for attendees to learn about diamond exploration, advanced research-level analysis, diamond morphology, inclusion chemistry, and geologic occurrences in a way that will inspire their future studies and career choices. GIA’s contribution directly benefited these up-and-coming research scientists by reducing the attendance fees for the conference, permitting many students to attend who otherwise would have been unable to do so.

IDS was organized by Fabrizio Nestola, Graham Pearson, and Steven Shirey, under the auspices of the Diamonds and Mantle Geodynamics of Carbon (DMGC) consortium, part of the Deep Carbon Observatory (DCO). The school was sponsored by GIA, the DCO, the Italian Society of Mineralogy and Petrology (SIMP), and the University of Padua. The IDS website is at www.indimedea.eu/diamond_school_2015.htm. @chapter:29


Publication Year: 2007 Title: Serenity Coated Colored Diamonds: Detection and Durability Abstract: Gemological, spectroscopic, and chemical properties of diamonds treated using the new Serenity Technologies coating technique for inducing various “fancy” colors are reported. This technique produces colors that include intense blue, green, yellow, and orange to pink to purple-pink. The presence of a coating can be identified with magnification by observation of an interference-related colored (often bronzy) film, scratches, and colorless and/or dark areas on the surface of the pavilion facets. UV-Vis absorption spectra and chemical analysis provide confirmation of the treatment. Chemical analysis also revealed that the coating is a SiO2 film doped with Au and/or Ag for blue, pink, and yellow coloration, or with a surface Fe2O3 film for orange. No evidence was detected of either chemical diffusion or implantation of foreign elements into the diamond. While the colors produced by this treatment are stable to some standard jewelry repair and cleaning procedures, they are not considered permanent. @chapter:31


Publication Year: - Title: Fall 2018 G&G: Proceedings from the 2018 International Gemological Symposium Abstract: The 2018 GIA International Gemological Symposium, held October 7–9 in Carlsbad, California, was the sixth such
event dedicated to groundbreaking research across the gem and jewelry industry. A number of presentations discussed
inclusions in gem materials. The cover photo uses differential interference contrast to show the interior scene
of a diamond, where localized areas of high solubility appear as dissolution trigons decorating twin planes in a linear,
crystallographically aligned arrangement. Photomicrograph by Nathan Renfro; field of view 0.83 mm.

In celebration of Richard T. Liddicoat’s centennial birthday, GIA held its sixth International Gemological Symposium October 7–9, 2018, in Carlsbad, California. Nearly 800 attendees from 36 countries convened to exchange groundbreaking gemological research and to examine case studies taught by professors from the Harvard Business School. The Fall 2018 issue of G&G is dedicated to the proceedings of the Symposium. Featured are 37 speaker abstracts and 68 poster abstracts from the research track’s seven themes: Colored Stones and Pearls, Diamond Geology, Diamond Identification, Gem Characterization, Gem Localities, General Gemology and Jewelry, and New Technologies and Techniques.
In Colored Stones and Pearls, keynote presenter Barbara Dutrow considered tourmaline’s role as a geologic timekeeper, while Wuyi Wang began Diamond Identification with the color origin and type Ib designation of canary yellow diamonds. The Diamond Geology session opened with Graham Pearson’s discussion of “unconventional” formation settings, while Evan Smith headlined Gem Characterization by examining the genesis of natural type IIa and IIb diamonds. Lee Groat’s keynote presentation in Gem Localities related the importance of “fingerprinting” chemical analysis to origin determination. In General Gemology and Jewelry, Saleem Ali explored the challenges and emerging opportunities—including education, beneficiation, and environmental remediation—in creating a sustainable mine-to-market colored gemstone supply chain. In New Technologies and Techniques, keynote speaker Daniel Twitchen reviewed advances in the chemical vapor deposition (CVD) process used to create laboratory-grown diamonds.
The poster presentations, on display and available for viewing by attendees for all three days, are also captured in this issue of G&G.
In the closing session, the Futurescape Forum offered an illuminating forecast from six influential leaders in the gem and jewelry industry. The panelists discussed sourcing and production, the online vs. brick-and-mortar store retail experience (including Internet vs. in-person auctions), the impact of laboratory-grown material on the diamond market, and adapting to a millennial workforce.
The Fall 2018 issue also contains a photo montage with scenes captured during the Symposium, from the Music Paradigm opening session to the farewell reception. @chapter:20


Publication Year: 2022 Title: Hydrothermal Synthetic Ruby Abstract: Figure 1. Photos of the hydrothermal synthetic ruby in daylight and short-wave UV light. Photos by Diego Sanchez.
Hydrothermal synthetic ruby was first introduced to the market in the 1960s (A. Peretti and C.P. Smith, “An in-depth look at Russia’s hydrothermal synthetic rubies,” JewelSiam, April-May 1993, pp. 96–102). The hydrothermal process is very slow and requires high heat and very high pressure (400–600°C, 5,000–30,000 psi), mimicking the conditions deep in the earth that result in the formation of natural ruby. In this method, the corundum seed plates are suspended inside the growth chamber and nutrients are placed in the bottom. Slowly the nutrients dissolve and form a solution which deposits new synthetic corundum growth onto the seed crystal. The size of the synthetic crystal depends on the size of the seed, amount of nutrient solution, and time.
The Carlsbad laboratory recently received a 4.55 ct transparent cushion-cut hydrothermal synthetic ruby for an identification report (figure 1). This type of laboratory-grown ruby is seldom submitted to the laboratory today, though they were more prevalent in the 1980s. Gemological testing yielded an RI of 1.761–1.769 and a specific gravity of 3.99. Its fluorescence reaction was strong red to long-wave and medium red to short-wave UV radiation, and its pleochroism was orangy red to purplish red. These properties are typical of most rubies, natural or laboratory grown.
Chemical analysis was done by EDXRF and showed a high amount of chromium (1550 ppma), low iron (153 ppma), titanium (25.5 ppma), no gallium, and very low vanadium (2.24 ppma), which matches the synthetic corundum chemistry.

Figure 2. The chevron growth structure observed in the hydrothermal synthetic ruby. Photomicrograph by Shiva Sohrabi; field of view 4.79 mm.
Magnification showed characteristic internal features of hydrothermal synthetic corundum such as subparallel striations and angular/zigzag (chevron) graining using a standard gemological microscope in conjunction with fiber-optic light or diffused light (figure 2).

Figure 3. The DiamondView image of the chevron growth pattern in the hydrothermal synthetic ruby. Photomicrograph by Shiva Sohrabi; field of view 8.63 mm.
The baseline-corrected spectra showed very strong water peaks in the region between 3200 and 3600 cm–1, which is strongly indicative of hydrothermal synthetic origin. (The instrument was baseline corrected to remove the water signal from the atmosphere as well as having the sample chamber purged with dry air to minimize the detection of water from the atmosphere.) Luminescence images in an ultra-short-wave UV radiation DiamondView showed an interesting chevron growth pattern as well with red fluorescence, further confirming hydrothermal synthetic origin (figure 3).
While hydrothermal synthetic rubies are not as common in the gem trade today, it is helpful to review the distinctive features and characteristics that make them identifiable. @chapter:12


Publication Year: - Title: A Look Back — and Forward — After 40 Years in the Gem and Jewelry Industry Abstract: Russell Shor, left, meeting with De Beers’ sales manager Michael Grantham, center, and De Beers CEO Nicky Oppenheimer, right. London, 1988. Photo provided by Russell Shor/GIA.
On a rainy spring morning exactly 40 years ago, I made my first visit to 47th Street to meet a venerable diamond dealer named Seymour Rosenthal. I was very early, being anxious, so I waited at Berger’s Deli with a coffee, and watched an unending parade of humanity of every race, creed and color pass by, many stopping to show a stone to a prospective client or (as I learned later) put in some “asks."
At my appointment, I mentioned this scene to Mr. Rosenthal who was then head of the Diamond Trade Association, and he told me “… all that matters is to be honest and have the right stone at the right price.” I told myself right away that I was going to love this industry.
And I have. And the people in it.
He also told me that this industry was like a big family — it has it spats and we compete fiercely, but when it counts, we all pull together. I experienced this not long afterward when I was visiting a diamond office in Singapore and when the conversation finished, the dealer rose from his chair, waved his hand toward himself and said, “Come.”
I asked where to.
“Come take Shabbat with us.”
“You want me to come to your home?”
“When you’re here, you’re family,” he said.

Russell Shor examines a frieze made from photos and materials from the ancestral home of Ashok Virani during a visit to his home in Surat, India on Brothers’ Day, 1997. Photo taken by Mark Boston and provided by Russell Shor/GIA.
And a few years after that, I found myself in Surat, India on “Brothers’ Day,” when most diamond offices close for the holiday. The owner of a diamond manufacturing operation came to the hotel where my colleague, a De Beers’ broker, and I were staying and took us to his home where his four brothers were waiting.
“You are like brothers,” he told us and made us feel like it the rest of the day, even though we had not met very often before then.
Perhaps such incidents happen in other industries, but I like to think they are part of the special nature of our industry.
And, of course beyond the people, there are the gems themselves. I’ve been privileged to hold and examine the 910 carat (ct) diamond from Letseng; a 15 ct Kashmir sapphire with such a velvety blue glow, it made the rest of the world seem dull by comparison; a large drop pearl worn by Queen Marie Antoinette; a 70 ct emerald that had been part of Catherine the Great’s jewels; the Fancy Deep blue Heart of Eternity diamond; a jade necklace whose intense green stopped me in my tracks at a crowded trade show — and so many others.
The amazing thing is that they are all beautiful accidents of nature — a convergence of random forces and materials that crystalized into magical forms. These are privileges no other livelihood can offer.
Of course, the gem and diamond industry has seen transformational changes in the years since I entered it. Mr. Rosenthal still had an old diamond scale that balanced little brass weights on his desk when I met with him. The digital revolution had just begun.

To review the changes that have enveloped the diamond and gem industry in the past 40 years would be too space-consuming and superfluous — we hear every day how the internet has changed everything and is still changing things; how women have taken their rightful place in business life, but there’s still a way to go; how corporate responsibility and ethical sourcing are gaining ground, though perhaps too slowly for some; and the end of De Beers’ rule of the diamond trade.

Russell Shor with Barbara Masekela, chief of staff to Nelson Mandela. Johannesburg, 1999. Photo provided by Russell Shor/GIA.
No matter what you might thing about the “old” De Beers, it maintained order in the market that kept diamond businesses from going too far off the path. Unfortunately in the past decade, a number of diamond firms abandoned the best practice principals that made the trade work for many years. Now the entire trade is suffering from their transgressions, especially inflating their creditworthiness, after huge defaults prompted the major banks to pick up and leave.
Looking forward, there are some serious headwinds facing the diamond industry. China has seen a lot of growth, but it is not the omnivorous panacea predicted by Bain & Co. early in the previous decade. And the financial challenges facing millennials — rising housing costs, medical care and debt — will consume their discretionary incomes in ever-increasing amounts.
In such a stressed economic environment, laboratory-grown diamonds may look ever more attractive to some buyers who are still fascinated by the beauty of their fire and brilliance. Diamond mining companies, in cooperation with their clients, are addressing this by developing the fascinating stories that appeal to millennial consumers. They hope this will put natural diamonds higher on their priority list.
There have been attempts by some diamond dealers to tweak the growth process to make them more “natural” looking, then “testing” to see if gemological laboratories can catch them. Fortunately, because of the considerable resources GIA devotes to research and the expertise of the its staff, the Institute keeps ahead of such attempts and continues to be able to definitively recognize all laboratory-grown diamonds and known treatments.

Russell Shor holds the 910 Lesotho Legend in 2018. Photo provided by Russell Shor/GIA.
I’ve been proud and privileged to have been able to tell our industry’s story for 40 years and I believe it still has many good ones to tell. I hope to stay around for a bit to tell a few more and to play with a few more treasures.
One thing I hope never changes: the warm welcome for anyone who is ethical and has the right stones at the right price. @chapter:33


Publication Year: 2013 Title: Montana Moss Agate: Collectible Chalcedony from the Yellowstone River Abstract: The expansion of various mining projects in Canada’s North (Northwest Territories, Yukon, and Nunavut) is set to lead the country in economic growth over the next two years. Spinoff activity that accompanies mine-related prosperity is also expected to increase based on pending mines in the assessment phases or preproduction stages, thus further boosting employment and local economic development. Production in these areas is expected to last well into the coming decades. Environmental groups and local residents are also interested in the impact on the Canadian North ecosystem as well as the long-term effects on the towns and industry when the boom is over.

Abstracted by Edward R. Blomgren @chapter:24


Publication Year: 2020 Title: Dutrowite: New Mineral Species of Tourmaline Abstract: Left: Professor Barbara Dutrow has been honored with the naming of the new mineral dutrowite. Photo by Kevin Schumacher. Right: Sample of dutrowite (brown) and dravite (blue) tourmalines in meta-rhyolite from Italy. Courtesy of Cristian Biagioni.
A newly discovered mineral species of the tourmaline group has been named in honor of Dr. Barbara Dutrow (see above, left). Dutrowite (above, right) was discovered in the Apuan Alps of Tuscany, Italy, and has been recognized by the International Mineralogical Association. The Austrian, Italian, and Swedish researchers who discovered the mineral named it in recognition of Dr. Dutrow’s teaching and research contributions, particularly on tourmaline and its formation. She is the Gerald Cire and Lena Grand Williams Alumni Professor in the Department of Geology and Geophysics at Louisiana State University in Baton Rouge. In 2007, she was a coauthor of the 23rd edition of Manual of Mineral Science, a standard reference textbook for the study of minerals. Since 2016, Dr. Dutrow has served on the GIA Board of Governors. @chapter:13


Publication Year: - Title: US Consumer Confidence Remains Strong; Alluvial Diamond Tracking and Illegal Gold Abstract: Operations at Alrosa’s Lomonosov deposit in Western Russia. Alrosa, along with De Beers, has drastically reduced sales of rough diamonds to deal with the supply overhang. Photo Russell Shor/GIA

Consumer confidence in the U.S. remained strong in August, despite the volatile stock market and increased costs stemming from the trade war with China, according to The Conference Board, which conducts the monthly Consumer Confidence Survey.
“Consumer confidence was relatively unchanged in August, following July’s increase,” said Lynn Franco, senior director of economic indicators at The Conference Board. “Consumer expectations cooled moderately, but overall remain strong. While other parts of the economy may show some weakening, consumers have remained confident and willing to spend. However, if the recent escalation in trade and tariff tensions persists, it could potentially dampen consumers’ optimism regarding the short-term economic outlook.”
Many economists believe that signs of a recession have been developing, but that positive attitudes of U.S. consumers and their spending, have kept the economy from sliding into it.
RETAIL NUMBERS

Some U.S. independent jewelers, notably at the higher end, have done well this year, but the chains continue to report lackluster results.
Signet group reported a 1% decline in same store sales for the second quarter of the fiscal year, with its Zale Corp. division posting a slight rise, while Kay Jewelers and Jared the Galleria of Jewelry posting respective declines of 3% and 4%. Sales at the Piercing Pagoda, the kiosks selling low-priced jewelry, rose 11% and its online sales, which comprise 12% of the company’s business, rose 4%.
Tiffany & Co. registered a 3% decline in same store sales worldwide and 5% in North America for the first half of the year, with Asia sales falling 1%. The company said it still expects sales will increase by single digits worldwide through the holiday period.
HONG KONG SHOW
The protests in Hong Kong have taken their toll on the region’s retail trade, particularly after the participants disrupted the airports and rail services. Sales of jewelry, watches and luxury goods are down 9% for the first seven months of the year, with steep declines in July – 24% for all retail.
The September Hong Kong Jewellery & Gem Fair will go on as scheduled, but several groups, including the Israel Diamond Manufacturers Association, have asked the organizers to postpone it. In response, the fair is offering hotel deals to lure buyers who may be hesitating to attend.
ROUGH DIAMONDS
Rough diamond sales continue to plummet in the wake of oversupplies and tight financing.
De Beers August cycle sales totaled $280 million – about 40% lower than the August 2018 cycle, but slightly higher than July’s allocation of $250 million – the smallest in four years. De Beers’ sales are down 44% from last year’s levels. In addition to purchase deferments, the company is also buying back certain goods from clients.
In a New York Times interview, De Beers’ CEO Bruce Cleaver called the situation “significant indigestion” caused by the banks’ credit squeeze and difficult geopolitics.
Alrosa was predicting that the market will stabilize once “inventories even out in accordance with market demand,” but its sales ran 35% down through the first seven months of the year; the July allocation was down 50% from the previous year while August rough sales were down 36% from the same period last year. Like De Beers, Alrosa is allowing clients to defer rough purchases until early next year.
The company announced it may trim rough sales 5% to 10% next year if market conditions persist.
ALLUVIAL DIAMOND TRACKING
Artisanal diamond miners in the West African nation of Guinea may see more returns from their diamond finds through a traceable supply initiative developed by a Belgian sustainable development organization in cooperation with the Antwerp World Diamond Center (AWDC). The diamonds produced under this program will be traced from individual miners through vetted supply chains and sold in Antwerp under the auspices of the AWDC.
Such programs are rare for miners of alluvial diamonds because the deposits tend to be spread over wide areas and are difficult to monitor. The deposits are located in the Banankoro region of the country and the Belgian organization, CAP Conseil, has been monitoring production to ensure it conforms to Maendeleo Diamonds Standards introduced by the Diamond Development Initiative (DDI) in April.
The Maendeleo Diamond Standards are made of eight specific principles covering legality, consent and community engagement, human and worker’s rights, health and safety, violence-free operations, environmental management, interactions with large-scale mining and site closure. Each of these principles is comprised of provisions defined by measurable requirements, concrete performance criteria and a list of acceptable audit evidence.
DDI developed the Maendeleo Diamond Standards in consultation with a wide range of stakeholders, including governments, industry and local civil society organizations, as well as artisanal and small-scale diamond miners in four countries of Africa and South America. DDI then conducted pilot projects in Sierra Leone in 2012 and 2013 to field-test the system, and expanded it into a full program in 2014.
ILLEGAL GOLD
Reuters has reported that Swiss gold refiners and a major financial house have identified counterfeit gold bars used in refining – kilo bars with forged Swiss bank markings – in their facilities. The bars are real gold of high fineness, but are believed to be from suspect sources, such as money launderers, criminals and sanctioned regimes.
The report estimates that at least $50 million worth of gold bars have been identified by the refiners and J.P. Morgan, but adds that it is likely that many more have slipped through the checks and into the system. Those who found the counterfeits told Reuters they are very professionally done so there are probably “way, way more” in circulation.
While there is no conclusive evidence of the source of the gold bars, authorities believe they are being made in China and sold to traders in Japan, Hong Kong and Thailand.
A second report, this from the New York Times’ “The Weekly” series, notes that illegally mined gold in Colombia is still entering the market as well. This issue was first reported four years ago. The report described the environmental and social cost of Colombia’s illicit gold mining and noted that two-third of the metal coming from the country went through illegal channels.
This issue is critically important because numerous surveys have shown that consumers increasingly care about the origins of the products they buy. At the GIA Symposium last year and at a GIA-sponsored seminar in Las Vegas last June, top executives from across the industry stressed that ethics and sustainability are now top priorities to maintain consumer trust in their brands and products. @chapter:27


Publication Year: 2017 Title: La Lechuga Monstrance Abstract: La Lechuga, a gold devotional artifact made for the church of San Ignacio de Bogotá, features nearly 1,490 Colombian emeralds. © Museo de Arte del Banco de la República.

The gold monstrance of the church of San Ignacio de Bogotá, with almost 1,490 Colombian emeralds, is one of the most remarkable examples of baroque artistry in devotional objects (see above). With its abundance of fine-color emeralds, the artifact was dubbed La Lechuga (Spanish for “lettuce”). It is now on a brief European tour until January 3, 2018.

In 1700, the first year of Philip V’s reign, Spanish goldsmith José Galaz went to the territory of Nueva Granada to create a unique monstrance for the Jesuit church of San Ignacio de Bogotá. From 1700 to 1707, he used solid gold, enamel, and fine gem materials to create what became one of the most magnificent baroque monstrances ever produced. The approximately 80-cm-tall artifact is embellished with diamond, ruby, sapphire, amethyst, citrine, and baroque white natural pearl, along with the fine-quality Colombian emeralds. Further research might shed light on the provenance of these emeralds, which are possibly from the Muzo, Chivor, and Coscuez mines. Most have exquisite color and clarity, and the profusion of these gemstones in the circular aura makes it distinctively green. An interesting feature is the use of pearls in the gold lunette, the container where the host for the Eucharist is kept. Normally these lunettes have a crescent shape and are set with diamonds or no gems at all.

This monstrance was purchased by the Banco de la República de Colombia in 1985 and is now part of its Museo de Arte Miguel Urrutia collection. As one of Colombia’s most important treasures, it almost never leaves the country. An exception was made in 2015 when it went to the Museo del Prado in Madrid, and in 2017 it has been on public display at the Museu Nacional de Arte Antiga in Lisbon (June 21–September 13) followed by an exhibition at the Louvre in Paris (until January 3, 2018). This tour offers a unique opportunity for visitors outside Colombia to experience this outstanding Iberian baroque monstrance and its important gemological content. @chapter:26


Publication Year: 1990 Title: Winter 1990 G&G Book Reviews Abstract: “Gem Testing, 10th Edition”
By Basil W Anderson, revised by E. Alan Jobbins, 390 pp., illus., publ. by Butterworths , London, 1990. US$49.95

“Engagement and Wedding Rings: The Definitive Buying Guide for People in Love”
By Antoinette Matlins, Antonio Bonanno, and Jane Crystal, 269 pp., illus., publ. by Gemstone Press, South Woodstock, VT, 1990. US$14.95

“Islamic Rings and Gems: The Zucker Collection”
Edited by Derek J. Content, 551 pp., illus., publ. by Philip Wilson Publishers, London, 1987. US$115.00

“The Diamond Ring Buying Guide: How to Spot Value and Avoid Ripoffs”
By Renee Newman, 140 pp., illus., publ. by International Jewelry Publications, Los Angeles, 1989. US$12.95

“Le Lapis Lazuli, Son Histoire, Ses Gisements, Ses Imitations (Lapis Lazuli, Its History, Deposits, and Imitations)”
By Claire do Cunha, 139 pp., illus., publ. by Le Rocher, Monaco, 1989.

To view the full section, download the PDF above. @chapter:26


Publication Year: 2017 Title: Japanese Jadeite Tables Abstract: Characteristic features of jadeite specimens from Japan and other sources, and analytical techniques used in this study.

	LA-ICP-MS chemical data for Jadeite from Japan, Myanmar, Guatemala, and Russia. @chapter:37


Publication Year: 2016 Title: CVD Synthetic Diamond Over 5 Carats Identified by GIA Abstract: Figure 1. This 5.19 ct CVD synthetic diamond (10.04 × 9.44 × 6.18 mm, with J-equivalent color and VS2-equivalent clarity) is the largest GIA has identified to date. Photo by Johnny Leung and Tony Leung.

Chemical vapor deposition (CVD) technology has accelerated over the last several years, and the rapidly improving techniques have produced large, high-quality near-colorless and colorless synthetic diamonds. Two samples over 3 carats were reported in early 2016 as the largest CVD synthetics. GIA recently tested a CVD-grown synthetic diamond that weighed over 5 carats, marking a significant milestone.

The 5.19 ct cushion modified brilliant measuring 10.04 × 9.44 × 6.18 mm (figure 1) was submitted to GIA’s Hong Kong laboratory for grading service. The stone was not disclosed as a synthetic diamond. Using the lab’s standard screening and testing processes, it was identified as CVD synthetic. Following examination, a GIA Identification Report was issued and the stone was inscribed on the girdle with the report number and the words “Laboratory Grown,” following GIA’s protocols for undisclosed synthetics.

This is the largest CVD synthetic diamond GIA has examined to date, and the largest reported in the jewelry industry. It had J-equivalent color grade and VS2-equivalent clarity, comparable to a high-quality natural counterpart. Natural-looking internal inclusions such as needles and clouds were the major features (figure 2). Strong graining and a fracture in the table were also clearly observed under the microscope. It is worth noting that black inclusions, often contained in synthetic diamond, were not found in this CVD specimen, which could have been mistakenly identified as natural based on microscopic examination alone. This case therefore highlights the importance of using advanced spectroscopic instruments as well as conventional gemological techniques to ensure an accurate identification.

Figure 2. Needles and pinpoints were the major internal features. Black inclusions, a
common feature of CVD synthetic diamond, were not observed. Photo by Billie “Pui
Lai” Law.
Viewing the sample under a binocular microscope with cross-polarized light revealed irregular birefringence patterns with high-order interference colors, a common feature of CVD synthetic diamond (figure 3). Fluorescence images under the short-wave UV radiation of the DiamondView showed strong red fluorescence with irregularly distributed areas of violet-blue (figure 4). The images also revealed a layered growth structure, indicating a start-stop cycling growth process typical of CVD synthesis. Up to six growth layers basically parallel to the table were identified from the fluorescence features. These multiple growth segments make it possible to grow such a thick sample.

Figure 3. Microscopic examination between crossed polarizers revealed high-order
interference colors, attributed to strong lattice dislocation. Photo by Billie “Pui Lai” Law.

Figure 4. Fluorescence imaging from the DiamondView showed strong red fluorescence
with bundles of violet-blue. Up to six growth layers basically parallel to the table were
revealed. Photo by Billie “Pui Lai” Law.
Infrared absorption spectroscopy identified the sample as type IIa. Except for a very weak absorption at 1332 cm–1, no other absorption features (such as hydrogen-related defects) were detected. Photoluminescence (PL) spectra were collected at liquid nitrogen temperature with various excitation wavelengths. The SiV– doublet at 736.6 and 736.9 nm, a common feature of both CVD and HPHT synthetics and only rarely seen in natural diamond, was observed using 457, 514, and 633 nm laser excitation, suggesting the sample’s synthetic origin. Spectra acquired with 514 nm laser excitation also showed emissions from NV centers at 575.0 nm (NV0) and 637.0 nm  (NV–), with the NV0 center dominating in intensity (figure 5). The occurrence of a weak emission pair at 596.5 and 597.2 nm, in combination with the absence of H3 emission, unequivocally identified this as an as-grown CVD synthetic diamond. No post-growth annealing had been applied to improve its color appearance.

Figure 5. The photoluminescence spectrum acquired with 514 nm laser excitation
revealed strong emissions from NV centers in addition to emissions from SiV–.
Emissions at 596/597 nm indicated that this synthetic diamond was not annealed
after growth.
CVD synthetics are available from several sources. The gemological and spectroscopic features of this 5.19 ct sample are very similar to those GIA has examined from Washington Diamonds (now known as WD Lab Grown Diamonds). As diamond growth techniques continue to advance, we expect to see more high-quality samples, both in size and clarity. @chapter:15


Publication Year: 2015 Title: Exceptional Red Spinels and Fine Aquamarine Abstract: Figure 1. Superb Tanzanian red spinel marquise of 61.29 ct. Photo courtesy of Henn Gems .

              At the GJX show, Axel Henn (Henn GmbH, Idar-Oberstein, Germany) showed a superbly colored 61.29 ct Tanzanian red spinel measuring 36.49 × 18.44 × 13.55 mm (figure 1), along with two pear-shaped gems cut from similar rough. Red spinels of this size, color, and quality are exceptionally rare. Indeed, stones of such deep, rich color larger than 50 ct are almost unheard of.

According to Henn, this gem was from a find of three exceptionally large spinel crystals (one larger than 50 kg) recovered from a dried riverbed in the mid-2000s. Henn heard of the discovery through a local Tanzanian contact. The crystals needed to be hammered and trimmed, but they still produced cuttable rough of significant size, including a suite of gems totaling 174.58 carats. In his opinion, the 61.29 ct marquise is the finest of the lot.

This is likely the same discovery as the widely reported 2007 recovery of four giant spinel crystals weighing 52, 28, 20, and 5.7 kg from a zone in the Ipanko ruby and spinel mining area known as the “Joel Box.” Reported as having a “vibrant orangy, pinkish red color,” the largest crystal was broken up for transportation away from the mining area. The outside portions of crystals had some superb cuttable material, but the cores were mostly lower quality. Although the eventual yield was said to be as low as 3%, the crystals had the potential to produce many thousands of carats of cut gems, including significant pieces of over 50 ct. The 61.29 ct marquise is likely part of this yield.

Henn also displayed a superb 450.08 ct rectangular (corners-on) step-cut aquamarine (figure 2). This gem possessed the coveted pure blue “Santa Maria” color, with no hint of green or yellow (this name refers to a mine near Santa Maria de Itabira in Minas Gerais, Brazil). The gem was of stunning clarity—this cutting style is very revealing of any imperfections—and was fashioned from rough recovered in 1927. Henn said he purchased the rough from an “old gemstone family,” and it had been “kept in the basement” for generations.

Figure 2. Among the many fine aquamarines at Axel Henn’s booth, the standout was this 450.08 ct square step-cut gem. Photo by Duncan Pay/GIA; courtesy of Henn Gems. @chapter:1


Publication Year: 2018 Title: Type IIa Diamond with Extraordinary Etch Channels Abstract: Figure 1. A rare 1.77 ct type IIa diamond with significant etch channels caused by dissolution along dislocations. Photo by Aurélien Delaunay.

Etch channels are rare inclusions in natural diamonds, both type I and type II (see T. Lu et al., “Observation of etch channels in several natural diamonds,” Diamond and Related Materials, Vol. 10, No. 1, 2001, pp. 68–75). Recently, the Laboratoire Français de Gemmologie received a 1.77 ct round brilliant-cut diamond containing numerous large etch channels, a feature appreciated by inclusion collectors. The gem had K color and I1 clarity due to the etch channels and their reflectors (figure 1). Infrared absorption spectroscopy revealed a type IIa diamond.

Figure 2. Etch channels with rhombic openings at the surface of the diamond. Photomicrograph by Aurélien Delaunay; field of view 2.22 mm.

Figure 3. Rare etch channel with a pyramidal termination in a 1.77 ct type IIa diamond. Note the lateral continuation of the dissolution. Photomicrograph by Aurélien Delaunay; field of view 1.39 mm.
Dissolution etch channels in diamond are rare but can have various forms (M. Philippe and E. Fritsch, “Dissolved dislocation: Inclusions not always easy to identify, part I,” Revue de Gemmologie, Vol. 200, 2017, pp. 11–22, in French). They are due to the dissolution of dislocations inside the crystal. These dislocations might be growth dislocations or caused by later deformation. One type of etch channel in diamond consists of regular and parallel lines related to diamond’s crystallographic structure. The other type, the kind exhibited in this diamond, is a worm-like ribbon due to crystallographic defects. All dissolution etch channels have rhombic openings at the surface of the diamond (figure 2); a few have a pyramidal termination and restart in another direction (figure 3). This is a rare occurrence and confirms that dissolution can be stopped—or slowed—by defects in the crystal structure. In addition, the dissolution can start in an easier direction, such as a dislocation.

Etch channels are rarely observed in cut gem diamonds. But when gemologists observe a specimen like this one, it is always a pleasure for the eyes and a curiosity of nature. @chapter:11


Publication Year: 1981 Title: Zabargad: The Ancient Peridot Island in The Red Sea Abstract: Reflecting on his 1980 visit to Zabargad, the author provides an update on this relatively unknown island and the beautiful peridots for which it has gained fame. He complements his discussion of the geology of Zabargad, the peridot occurrences, the mining techniques, and the characteristics of the gemstone with a look at the ancient history of the island and the etymological changes surrounding the stone's current name, peridot. Although somewhat low on the hardness scale, this magnificent gemstone has regained popular appreciation, and the crystals from Zabargad are still among the finest in the world. @chapter:3


Publication Year: 2021 Title: Star Rhodochrosite Abstract: Figure 1. This 19.44 ct orangy pink rhodochrosite contains a four-rayed star. Photo by Diego Sanchez.

The Carlsbad laboratory received a 19.44 ct semitransparent orangy pink round cabochon for identification (figure 1). With the unaided eye, a four-rayed star could be seen across the dome. Standard gemological properties, including a refractive index of 1.68–1.58 with a birefringence blink and a specific gravity of 3.71, were documented and consistent with the gem species rhodochrosite.

Figure 2. Fluid inclusions in a step-like pattern running parallel to the base of the rhodochrosite cabochon. Photomicrograph by Nicole Ahline; field of view 4.14 mm.
Asterism is created when light is reflected off well-aligned inclusions and returns as a star across the surface of the stone. Such stones are commonly cut as cabochons to properly display this phenomenon. The asterism seen in this rhodochrosite was created from fluid inclusions that run parallel to the base of the cabochon (figure 2). The fluid inclusions were rhomboid in shape, which caused the star to have four rays. It is worth noting that the rays of the star did not cross perpendicular to each other, and this is due to the rhomboid fluid inclusions intersecting at an angle not at 90°.
Many gemstone species display asterism, but this was the author’s first opportunity to see a star rhodochrosite. This 19.44 ct stone is a perfect example of why one should always keep an eye out for the unexpected. @chapter:19


Publication Year: 2016 Title: Imperial Flame Topaz Sculpture Abstract: Figure 1. The Imperial Flame, a magnificent natural-color Brazilian topaz, was cut from a 615 ct crystal recovered some 20 years ago. The finished 89.53 × 20.56 × 19.15 mm sculpture weighs 332.24 ct. Photo courtesy of Sonja Kreis Unique Jewelry.

	One of the 2016 Tucson show’s most noteworthy gems was a 332.24 ct freeform Imperial topaz (figure 1) at the GJX booth of gem cutter Alexander Kreis (Sonja Kreis Unique Jewelry, Niederworresbach, Germany). Topaz with this red, pink, or orangy yellow color component is rare and highly sought after in the trade. Named the “Imperial Flame” by the Kreis family, the crystal was reportedly recovered from Brazil’s Ouro Preto topaz mines two decades ago. Topaz has been known from this area of Minas Gerais since 1768 (P.C. Keller, “The Capão topaz deposit, Ouro Preto, Minas Gerais, Brazil,” Spring 1983 G&G, pp. 12–20).

	Although mining was extensive at Ouro Preto in the mid-1990s (D.A. Sauer et al., “An update on Imperial topaz from the Capão mine, Minas Gerais, Brazil,” Winter 1996 G&G, pp. 232–241), the Kreis family confirmed that there is currently no large-scale mining. They visited the area after a collector informed them of a 615 ct crystal with exceptional color and clarity (figure 2). According to their contact, the crystal is “old production” mined at least 20 years ago. After analyzing the rough over a period of four months, the family purchased it in December 2015 with the objective of cutting the largest, highest-quality Imperial topaz known.

Figure 2. The original 615 ct Imperial topaz crystal from which Alexander Kreis fashioned the 332.24 ct Imperial Flame. Photo courtesy of Sonja Kreis Unique Jewelry.

	Due to the gem’s perfect basal cleavage, cutters must avoid grinding the stone perpendicular to the cleavage plane, while also accounting for inclusions that might cause the stone to break on the wheel. According to Sauer et al. (1996), well-formed, largely inclusion-free crystals typically yield up to 2 ct per gram (5 ct), which is a 40% recovery rate. Cutting the Imperial Flame took approximately eight days, spread over a period of 3–4 weeks, to allow Kreis to make trial carvings with smaller Imperial topaz pieces to test his cutting concepts. The cutting process began with sawing off the included portions and grinding to shape the solid crystal (figure 3), followed by faceting and carving to produce the reflective, grooved surfaces. The fashioning process yielded a spectacular gem measuring 89.53 × 20.56 × 19.15 mm. At 332.24 ct, it had a finished yield of 54%.

Figure 3. After trimming away included portions of the crystal’s base, Alexander Kreis gently removes any surface-reaching inclusions and begins to shape the crystal to his own unique design. Photo courtesy of Sonja Kreis Unique Jewelry.

	Intended as an arresting gem sculpture for a connoisseur or high-end collector, the piece is for sale. @chapter:1


Publication Year: 1985 Title: A Status Report on Gemstones from Afghanistan Abstract: Although Afghanistan has historically been well known for its lapis lazuli deposits, significant amounts of fine emerald, tourmaline, kunzite, and some rubies are now emerging from that embattled nation. Emeralds come primarily from the Panjshir Valley, northeast of Kabul. Large amounts of green, blue, and pink tourmaline, as well as considerable quantities of kunzite and some aquamarine, have been taken from the pegmatites of the Nuristan region, east of Panjshir. Smaller quantities of fine ruby have been found in the Sorobi region, between Jalalabad and Kabul. The occurrence, mining, and distribution of these gem materials are summarized, as are their gemological properties. Lesser amounts of garnet, amethyst, spinel, and morganite have also been located. The prospects for future production of emeralds and pegmatite gems, in particular, are excellent. @chapter:1


Publication Year: 2023 Title: Cross in Natural Diamond Abstract: A cross pattern observed in this DiamondView image of a 0.31 ct D-color type IIa diamond. Image by Priyanka Kadam.
DiamondView imaging of the 0.31 ct D-color type IIa modified round brilliant diamond shown in the figure above revealed an interesting fluorescence pattern. The image displayed blue fluorescence as well as a darker pattern in the shape of a cross. One of the pavilion main facets was longer than the other three, producing this distinct cross pattern when the diamond was viewed through the table. Depending on the specific angle of the pavilion main facets, such a distinct pattern might not be visible in the DiamondView. @chapter:15


Publication Year: 1990 Title: Diamond Grit-Impregnated Tweezers: A Potentially Destructive Gemological Tool Abstract: The authors examined diamond grit-impregnated tweezers that reportedly were being marketed out of Japan. The tweezers were shown to damage virtually any type of gemstone with the possible exception of diamond; owners of these tweezers are advised to use caution. @chapter:29


Publication Year: 2023 Title: The history of gemstones in Chanthaburi_17 Abstract: In the later years, around the 5th reign, there are records from Herbert Warington Smyth's book "Five Years in Siam" that mention Gula(Kula) people from Shan State arriving in Siam with the Borneo Company as part of the mining community. Initially settling in Bangkok, they were preceded by skilled Thai gem traders who had moved to the capital before relocating to the Chanthaburi. Some were merchants specializing in gem selection, while others were involved in mining operations. @chapter:25


Publication Year: - Title: Summer 2019 G&G: Mozambican Ruby, Challenges in Pearl Identification, and an Opal Inclusions Chart Abstract: The Summer 2019 edition of Gems & Gemology opens with a look at the past decade of ruby production in Mozambique, now the world’s leading supplier. The issue also features an investigation into low-temperature heat treatment of Madagascar sapphire, information on a source of black nephrite in southern China, a pair of pearl studies, and an opal inclusions chart.
A Decade of Ruby from Mozambique: A Review
While gemstones have been known from Mozambique for some time, the country became a major player in the trade after facet-quality ruby was unearthed in Niassa and, more importantly, Montepuez in 2009. In the lead article, Wim Vertriest and Sudarat Saeseaw provide a snapshot of the first decade of Mozambican ruby. The authors review production from the deposits, the characteristics of the rubies, and their impact on the market.
Madagascar Sapphire: Low-Temperature Heat Treatment Experiments
African corundum makes an encore in the second article. Known for its fine blue sapphire, Madagascar also produces specimens that react well to heat treatment at low temperatures to lighten their color. E. Billie Hughes and Rosey Perkins perform heating experiments to separate heated from unheated blue Madagascar sapphires.
Black Nephrite Jade form Guangxi, Southern China
A nephrite deposit in the southern Chinese region of Guangxi, discovered in 2012, has produced black nephrite jade that is popular in the Chinese market. A team of authors led by Qian Zhong study the gemological characteristics of 12 rough nephrite specimens from this locality and find that high iron content is responsible for their color and high refractive index. The authors assert that Guangxi’s nephrite deposits are part of a larger jade formation belt in southern China.
Evidence of Rotation in Flame-Structure Pearls from Bivalves of the Tridacnidae Family
Non-nacreous pearls with flame structures from the Tridacnidae family may exhibit some distinctive properties, including pseudo-chatoyancy as well as spirals and or/blade impeller patterns at the apex or base. Jean-Pierre Gauthier and coauthors examine 37 pearls from the Tridacnidae family to understand their properties and formation. The patterns seem to suggest rotation of the pearls during formation or during the growth phase prior to harvesting.
A Pearl Identification Challenge
Nicholas Sturman and a team from three different research institutes investigate the properties of two pearls that were anything but routine. The researchers were unable to positively identify the pearls’ origin (natural or cultured), their growth environment (freshwater or saltwater), or the producing mollusk.
Inclusions in Natural, Treated, Synthetic, and Imitation Opal
The issue also contains the fifth in G&G’s series of inclusion charts. Nathan Renfro and coauthors present a chart of micro-features in natural, treated, synthetic, and imitation opal.
Lab Notes
GIA laboratory staff members present their latest findings in the Lab Notes section, including a resin-coated and clarity-enhanced aquamarine pendant, a rough diamond coated with fake green “radiation stains,” and a report on a color-change spessartine garnet.
Micro-World
The Micro-World section, dedicated to the inner world of gemstones, features a purple fluorite inclusion in a Russian emerald, a Mexican opal with a large fluid inclusion, and an inclusion-rich black topaz from Utah.
Diamonds from the Deep
In G&G’s newest section, Karen Smit and Steven Shirey look at the relationship between kimberlites and diamonds and provides an understanding of how diamonds travel to the earth’s surface after formation in the mantle.
Gem News International
Finally, GNI correspondents from around the world report on jadeite jade from the Polar Ural Mountains of Russia, rubies from the Rock Creek deposit in Montana, and the leveraging the tagua nut as a sustainable alternative to ivory in jewelry. @chapter:3


Publication Year: 1982 Title: Gem-Quality Grossular Garnets Abstract: The gemological classification and identification of gem grossular garnets is examined through the study of 105 gem-quality grossulars. These specimens were measured for refractive index, specific gravity, absorption spectrum, color, and chemical composition. From these data, the authors were able to reexamine the ranges of physical and optical properties that are characteristic of the gem species grossular. In addition, they discuss the problems encountered in defining the two gem varieties of grossular, tsavorite and hessonite. @chapter:6


Publication Year: 2023 Title: Yellow Zoning in Pink Diamonds Abstract: Fancy brownish pink pear and rectangular diamonds, each weighing 0.25 ct, shown in diffused light (A and C) and in long-wave UV light (B and D). Photos by Shiva Sohrabi.
Recently GIA’s Carlsbad laboratory received a few unusual natural, nitrogen-rich type IaA pink diamonds for color origin and identification service. The pink color of these diamonds is caused by the 550 nm visible absorption band, with the color concentrated within parallel narrow bands known as pink graining (S. Eaton-Magaña et al., “Natural-color pink, purple, red and brown diamonds: Band of many colors,” Winter 2018 G&G, pp. 352–377). In diffused light, they displayed faint yellow color zoning (see above, A and C). Further inspection under long-wave UV revealed strong yellow fluorescence confined to areas with yellow color zoning (see above, B and D).
Photoluminescence (PL) spectra (excited by 514 nm laser) collected from the area with yellow zoning show a broad band centered at ~710 nm. This broad emission band and corresponding strong yellow fluorescence are typically observed in yellow or orange diamonds colored by the 480 nm visible absorption band (C.M. Breeding et al., “Naturally colored yellow and orange gem diamonds: The nitrogen factor,” Summer 2020 G&G, pp. 194–219). These gemological and spectroscopic features suggest that separate color centers produce pink and yellow colors within these diamonds, though the 480 nm visible absorption band cannot be detected with ultraviolet/visible/near-infrared (UV-Vis-NIR) spectroscopy (possibly due to the fact that the yellow color zone is volumetrically small compared to the rest of the diamond, and that the UV-Vis-NIR absorption spectroscopy is a bulk analysis technique).
The mechanism of the formation of these unusual pink diamonds has not been determined and to the authors’ knowledge, such diamonds showing localized regions colored by the 550 nm band and 480 nm band have not yet been documented. Since we know very little about the physics of the 480 and 550 nm visible absorption bands, their co-occurrence within single diamonds might help us to better understand the structures of defects that are related to these features. By paying careful attention to the details of color and fluorescence zoning, more of these unusual rare pink diamonds may be identified. @chapter:11


Publication Year: 2013 Title: Large Synthetic Moissanite with Silicon Carbide Polytypes Abstract: Figure 1. This 29.73 ct synthetic moissanite (left) was submitted as a black diamond. Surface-breaking graphite inclusions were easily observed, including the largest one at the upper left table edge. The mosaic patterns on the table surface became distinct when viewed under a Raman microscope (right). Photos by Sood Oil (Judy) Chia, left, and Kyaw Soe Moe, right.

Silicon carbide (SiC) is composed of a carbon atom surrounded by four silicon atoms in a tetrahedral form. Colorless synthetic moissanite is pure silicon carbide; the incorporation of impurities produces colors, including black. Its high hardness (second only to diamond) and thermal conductivity make it a convincing diamond simulant. Both transparent and opaque synthetic moissanites have been submitted to GIA’s laboratory over the past two decades. In this report, we examine a 29.73 ct synthetic moissanite submitted as a black diamond (figure 1, left).
An uneven surface and surface-breaking black inclusions were visible with the unaided eye. Mosaic patterns of light and dark gray regions were observed under a microscope and became distinct in the Raman image (figure 1, right). Small cavities and polish lines in different directions were present on the table surface, and a granular texture was observed in a large cavity on the girdle. Raman spectroscopy identified the dark gray regions as silicon carbide.

Interestingly, each random testing spot showed mixed bands of silicon carbide polytypes (i.e., identical chemical composition but a slightly different crystal structure). The polytype 6H-SiC (6 = the number of stacking sequences, H = hexagonal, and SiC = silicon carbide) was detected by Raman bands at 789.6, 765.0, and 148.0 cm–1. Other polytypes were also distinguished by Raman bands: 3C-SiC (C = cubic) at 970.1, 968.4, 797.8, 795.4, and 788.2, cm–1; 4H-SiC at 785.7 cm–1; and 15R-SiC (R = rhombohedral) at 768.4 cm–1 (figure 2; see also P. Colomban, “SiC, from amorphous to nanosized materials, the example of SiC fibers issued of polymer precursors,” in M. Mukherjee, Ed., Silicon Carbide—Materials, Processing and Applications in Electronic Devices, InTech, 2011, pp. 161–186). In addition to these bands, a sharp Raman band assigned to silicon was detected at 520.2 cm–1 at a few spots. Bands corresponding to 6H-SiC at 238.8 and 148.0 cm–1 could not be detected at all measurement locations. Light gray regions were identified as silicon at 520.0 cm–1 (figure 2, left inset). Black inclusions, both eye-visible and microscopic, were confirmed as graphite. As figure 3 illustrates, the micro-image of a graphite inclusion showed an amorphous graphite vein (broad Raman bands at approximately 1561.0 and 1339.0 cm–1) inside a crystalline graphite matrix (sharp bands at 1580.0 and 1350.0 cm–1)

Figure 2. Each random spot showed mixed Raman bands of silicon carbide polytypes: 6H-SiC at 789.6, 765.0, and 148.0 cm–1; 3C-SiC at 970.1, 968.4, 797.8, 795.4, and 788.2 cm–1; 4H-SiC at 785.7 cm–1; and 15R-SiC at 768.4 cm–1. Silicon was also found at 520.2 cm–1 in spots 2 and 3. Bands at 238.8 cm–1 (possibly related to 6H-SiC) and 148.0 cm–1 (6H-SiC) were missing at spot 3. Light gray regions with a band at 520.0 cm–1 (left inset) were identified as silicon; the black regions were identified as graphite. The spectra have been shifted vertically for clarity. Photo by Kyaw Soe Moe (right inset).

Figure 3. Micro-imaging of a graphite inclusion (inset) showed a vein in matrix. The matrix was composed of crystalline graphite, as suggested by sharp Raman bands at 1580.0 and 1350.0 cm–1. The vein was identified as amorphous graphite by broad bands at approximately 1561.0 and 1336.0 cm–1.  Photo by Kyaw Soe Moe (inset).
During SiC growth, rotation along the covalent bond generated alternate stacking layers of Si and C atoms along the c-axis with different structural sequence, which is noticeable in the (1120) plane but not along the basal plane. This rotation can occur at very low energy. Since constant growth energy is difficult to control, two or more silicon carbide polytypes can form simultaneously during the growth process; this phenomenon is called polytypism. Raman spectroscopy has been used to detect these polytypes. Although there are more than 250 known polytypes, SiC can be classified as either beta (β) or alpha (α) type. The beta type crystallizes in cubic lattice symmetry (e.g., 3C-SiC), the alpha type in hexagonal symmetry (e.g., 6H-SiC).
Traditional growth methods for silicon carbide involve sintering and hot pressing, and there are also newer techniques. Reaction-bonded silicon carbide can form when liquid silicon reacts with porous graphite. This silicon carbide contains both pure silicon (as a bonding component), and graphite. Earlier studies have suggested that black synthetic moissanite containing silicon inclusions could be grown by the physical vapor transport (PVT) method (see Winter 2009 GNI, p. 308; Spring 2011 Lab Notes, pp. 54–55). Using PVT, researchers have grown large silicon carbide bulk crystals up to 50 × 25 mm at a rate of 1.2 mm per hour at 10 kPa pressure (Q.-S. Chen et al., “Growth of silicon carbide bulk crystals by physical vapor transport method and modeling efforts in the process optimization,” Journal of Crystal Growth, Vol. 292, 2006, pp. 197–200). Nevertheless, Raman analysis at several testing points confirmed only the 6H-SiC polytype.
This sample was submitted for a Colored Diamond Identification and Origin Report, but one should always pay close attention to surface features, such as the mosaic pattern of light and dark gray regions in reflected light, together with surface-breaking black inclusions not observable in black diamond. @chapter:11


Publication Year: 2017 Title: Suggested Reading on Rubies and Their Inclusions Abstract: Anderson B.W. (1949) Reconstructed rubies. G&G, Vol. 6, No. 6, pp. 187–190.

Bowersox G.W., Foord E.E., Laurs B.M., Shigley J.E., Smith C.P. (2000) Ruby and sapphire from Jegdalek, Afghanistan. G&G, Vol. 36, No. 2, pp. 110–126, http://dx.doi.org/10.5741/GEMS.36.2.110

Chapin M., Pardieu V., Lucas A. (2015) Mozambique: A ruby discovery for the 21st century. G&G, Vol. 51, No. 1, pp. 44–54, http://dx.doi.org/10.5741/GEMS.51.1.44

Dirlam D.M., Misiorowski E.B., Tozer R., Stark K.B., Bassett A.M. (1992) Gem wealth of Tanzania. G&G, Vol. 28, No. 2, pp. 80–102, http://dx.doi.org/10.5741/GEMS.28.2.80

Emmett J., Scarratt K., McClure S.F., Moses T., Douthit T.R., Hughes R., Novak S., Shigley J.E., Wang W., Bordelon O., Kane R.E. (2003) Beryllium diffusion of ruby and sapphire. G&G, Vol. 39, No. 2, pp. 84–135, http://dx.doi.org/10.5741/GEMS.39.2.84

Gübelin E.J. (1940) Characteristics of Ceylon rubies. G&G, Vol. 3, No. 8, pp. 121–124.

——— (1940) Differences between Burma and Siam rubies. G&G, Vol. 3, No. 5, pp. 69–72.

——— (1944) Gemstone inclusions - Ruby. G&G, Vol. 4, No. 11, pp. 158–163.

——— (1949) Observations on reconstructed rubies. G&G, Vol. 6, No. pp. 186–187.

——— (1960) More light on beryls and rubies with synthetic overgrowth. G&G, Vol. 10, No. 4, pp. 105–113.

——— (1982) New synthetic rubies made by Professor P.O. Knischka. G&G, Vol. 18, No. 3, pp. 165–168, http://dx.doi.org/10.5741/GEMS.18.3.165

Gübelin E.J., Meyer H.O.A. (1981) Ruby in diamond. G&G, Vol. 17, No. 3, pp. 153–156, http://dx.doi.org/10.5741/GEMS.17.3.153

Hänni H.A., Schmetzer K. (1991) New rubies from the Morogoro area, Tanzania. G&G, Vol. 27, No. 3, pp. 156–167, http://dx.doi.org/10.5741/GEMS.27.3.156

Hänni H.A., Schmetzer K., Bernhardt H.J. (1994) Synthetic rubies by Douros: A new challenge for gemologists. G&G, Vol. 30, No. 2, pp. 72–86, http://dx.doi.org/10.5741/GEMS.30.2.72

Holmes R.J. (1947) The new Linde Stars man-made star rubies and star sapphires. G&G, Vol. 5, No. 11, pp. 452–456, 478–479.

Howell D.H. (1936) The ruby mines of Burma - Part 1 and 2. G&G, Vol. 2, Nos. 1/2, pp. 3–6, 31–34.

Huong L.T.T., Häger T., Hofmeister W., Hauzenberger C., Schwarz D., Long P.V., Wehrmeister U., Khoi N.N., Nhung N.T. (2012) Gemstones from Vietnam: An update. G&G, Vol. 48, No. 3, pp. 158–176, http://dx.doi.org/10.5741/GEMS.48.3.158

Kammerling R.C., Keller A.S., Scarratt K.V., Repetto S. (1994) Update on mining rubies and fancy sapphires in Northern Vietnam. G&G, Vol. 30, No. 2, pp. 109–114, http://dx.doi.org/10.5741/GEMS.30.2.109

Kane R.E. (1979) Synthetic rubies. G&G, Vol. 16, No. 7, pp. 206–207.

——— (1983) The Ramaura synthetic ruby. G&G, Vol. 19, No. 3, pp. 130–148, http://dx.doi.org/10.5741/GEMS.19.3.130

——— (1984) Natural rubies with glass-filled cavities. G&G, Vol. 20, No. 4, pp. 187–199, http://dx.doi.org/10.5741/GEMS.20.4.187

——— (1985) A preliminary report on the new Lechleitner synthetic ruby and synthetic blue sapphire. G&G, Vol. 21, No. 1, pp. 35–39, http://dx.doi.org/10.5741/GEMS.21.1.35

Kane R.E., Kammerling R.C. (1992) Status of ruby and sapphire mining in the Mogok Stone Tract. G&G, Vol. 28, No. 3, pp. 152–174, http://dx.doi.org/10.5741/GEMS.28.3.152

Kane R.E., McClure S.F., Kammerling R.C., Khoa N.D., Mora C., Repetto S., Khai N.D., Koivula J.I. (1991) Rubies and fancy sapphires from Vietnam. G&G, Vol. 27, No. 3, pp. 136–155, http://dx.doi.org/10.5741/GEMS.27.3.136

Keller P.C. (1982) The Chanthaburi-Trat gem field, Thailand. G&G, Vol. 18, No. 4, pp. 186–196, http://dx.doi.org/10.5741/GEMS.18.4.186

——— (1983) The rubies of Burma: A review of the Mogok Stone Tract. G&G, Vol. 19, No. 4, pp. 209–219, http://dx.doi.org/10.5741/GEMS.19.4.209

Kissin A.J. (1994) Ruby and sapphire from the Southern Ural Mountains, Russia. G&G, Vol. 30, No. 4, pp. 243–252, http://dx.doi.org/10.5741/GEMS.30.4.243

Koivula J.I., Johnson M.L. (1996) Rubies from Madagascar. G&G, Vol. 32, No. 2, pp. 133–135.

Koivula J.I., Kammerling R.C. (1988) Gem News: Ruby receives highest price at auction. G&G, Vol. 24, No. 4, pp. 252.

——— (1988) A gemological look at Kyocera’s new synthetic star ruby. G&G, Vol. 24, No. 4, pp. 237–240, http://dx.doi.org/10.5741/GEMS.24.4.237

Liddicoat R.T. (1969) Kashan flux grown rubies. G&G, Vol. 13, No. 1, pp. 30–34.
McClure S.F., Kammerling R.C., Fritsch E. (1993) Update on diffusion-treated corundum: Red and other colors. G&G, Vol. 29, No. 1, pp. 16–28, http://dx.doi.org/10.5741/GEMS.29.1.16

McClure S.F., Smith C.P., Wang W., Hall M. (2006) Identification and durability of lead glass-filled rubies. G&G, Vol. 42, No. 1, pp. 22–34, http://dx.doi.org/10.5741/GEMS.42.1.22

Meyer H.O.A., Gübelin E.J. (1981) Ruby in diamond. G&G, Vol. 17, No. 3, pp. 153–156, http://dx.doi.org/10.5741/GEMS.17.3.153

Muhlmeister S., Fritsch E., Shigley J.E., Devouard B., Laurs B.M. (1998) Separating natural and synthetic rubies on the basis of trace-element chemistry. G&G, Vol. 34, No. 2, pp. 80–101, http://dx.doi.org/10.5741/GEMS.34.2.80

Nassau K. (1981) Heat treating ruby and sapphire: Technical aspects. G&G, Vol. 17, No. 3, pp. 121–131, http://dx.doi.org/10.5741/GEMS.17.3.121

Peretti A., Schmetzer K., Bernhardt H.-J., Mouawad F. (1995) Rubies from Mong Hsu. G&G, Vol. 31, No. 1, pp. 2–26, http://dx.doi.org/10.5741/GEMS.31.1.2

Pham V.L., Pardieu V., Giuliani G. (2013) Update on gemstone mining in Luc Yen, Vietnam. G&G, Vol. 49, No. 4, pp. 233–245, http://dx.doi.org/10.5741/GEMS.49.4.233

Schmetzer K., Peretti A. (1999) Some diagnostic features of Russian hydrothermal synthetic rubies and sapphires. G&G, Vol. 35, No. 1, pp. 17–28, http://dx.doi.org/10.5741/GEMS.35.1.17

Schmetzer K., Schupp F.J. (1994) Flux-induced fingerprint patterns in synthetic ruby: An update. G&G, Vol. 30, No. 1, pp. 33–38, http://dx.doi.org/10.5741/GEMS.30.1.33

Schmetzer K., Hänni H.A., Jegge E.P., Schupp F.J. (1992) Dyed natural corundum as a ruby imitation. G&G, Vol. 28, No. 2, pp. 112–115, http://dx.doi.org/10.5741/GEMS.28.2.112

Schmetzer K., Hänni H.A., Schwarz D. (1996) Trapiche rubies. G&G, Vol. 32, No. 4, pp. 242–250, http://dx.doi.org/10.5741/GEMS.32.4.242

Schmetzer K., Steinbach M.P., Gilg H.A., Blake A.R. (2015) Dual-color double stars in ruby, sapphire and quartz: Cause and historical account. G&G, Vol. 51, No. 2, pp. 112–143, http://dx.doi.org/10.5741/GEMS.51.2.112

Schwarz D., Pardieu V., Saul J.M., Schmetzer K., Laurs B.M., Giuliani G., Klemm L., Malsy A.K., Erel E., Hauzenberger C., Du Toit G., Fallick A.E., Ohnenstetter D. (2008) Rubies and sapphires from Winza, central Tanzania. G&G, Vol. 44, No. 4, pp. 322–347, http://dx.doi.org/10.5741/GEMS.44.4.322

Shor R., Weldon R. (2009) Ruby and sapphire production and distribution: A quarter century of change. G&G, Vol. 45, No. 4, pp. 236–259, http://dx.doi.org/10.5741/GEMS.45.4.236

Smith C.P. (1996) Introduction to analyzing internal growth structures: Identification of the negative d plane in natural ruby. G&G, Vol. 32, No. 3, pp. 170–184, http://dx.doi.org/10.5741/GEMS.32.3.170

——— (2002) Diffusion ruby proves to be synthetic ruby overgrowth on natural corundum. G&G, Vol. 38, No. 3, pp. 240–248, http://dx.doi.org/10.5741/GEMS.38.3.240

Smith C.P., Gübelin E.J., Bassett A.M., Manandhar M.N. (1997) Rubies and fancy-color sapphires from Nepal. G&G, Vol. 33, No. 1, pp. 24–41, http://dx.doi.org/10.5741/GEMS.33.1.24

Sorokina E.S., Litvinenko A.K., Hofmeister W., Häger T., Jacob D.E., Nasriddinov Z.Z. (2015) Rubies and sapphires from Snezhnoe, Tajikistan. G&G, Vol. 51, No. 2, pp. 160–175, http://dx.doi.org/10.5741/GEMS.51.2.160

Spaulding D.L. (1956) The ruby mines of Mogok, Burma. G&G, Vol. 8, No. 11, pp. 335–342.
Vertriest W., Pardieu V. (2016) Update on gemstone mining in northern Mozambique. G&G, Vol. 52, No. 4, pp. 404–409, http://dx.doi.org/10.5741/GEMS.52.4.404 @chapter:0


Publication Year: 1994 Title: Winter 1994 G&G Lab Notes Abstract: Light Yellow Color-Treated Diamond
Carved Emerald Fetish
Feldspar: Separating Alkali from Plagioclase Species
Grossular-Andradite Garnet from Mali, West Africa
Bleached and Impregnated Jadeite Jade with Distinctive Surface Features
Imitation and Natural Spotted Malachite
Abalone "Mabe" Pearl
Non-Nacreous Cultured "Pearl"
Sapphire of Unusual Color
Synthetic Sapphire: Striae Resolution Technique

To view the full section, download the PDF above. @chapter:17


Publication Year: 2017 Title: Pyrope-Spessartine Color-Change Garnet with a High Grossular Component Abstract: Top: Photos of three garnet wafers under incandescent light and fluorescent light (a daylight-equivalent imitation). Bottom: Calculated color panels of three garnet wafers under CIE A illumination and CIE D65 illumination. Photos by Ziyin Sun.
During the 2016 Tucson Gem and Mineral Show, Jeff Aylor provided several transparent rough garnets, reportedly from Sri Lanka, to GIA for scientific examination. We noticed that the rough garnets showed obvious color change from yellow-green under daylight equivalent lighting to orange under incandescent illumination. Three rough garnets were polished into wafers and analyzed to fully understand the chemistry and color behavior of the material.

Standard gemological testing of three garnet wafers .revealed a refractive index (RI) from 1.76 to 1.77; hydrostatic specific gravity (SG) ranged from 3.93 to 4.00. Fluorescence was inert to long-wave and short-wave UV light. The stones did not show any pleochroism when utilizing the dichroscope. Using a handheld spectroscope, absorption lines in the blue and violet section, and very weak absorption bands at 520 and 573 nm, were observed. Microscopic examination showed intersecting long and short needles throughout. Graphite and quartz inclusions were also observed. All of these properties are consistent with garnet.

The chemical composition for each wafer was obtained with a ThermoFisher iCAP Q ICP-MS coupled with a New Wave Research UP-213 laser ablation unit. We concluded that this type of material contains 39.79%–52.66% spessartine, 21.71%–32.03% pyrope, 3.17%–7.28% almandine, 16.87%–22.46% grossular, 0.38%–0.72% goldmanite, and 0.11%–0.19% uvarovite (table 1). Based on the garnet classification from Stockton and Manson (“A proposed new classification for gem-quality garnets,” Winter 1985 G&G, pp. 205–218), this material should be classified as pyrope-spessartine. The V2O3, MgO, and MnO oxide wt.% are similar to the group 5 color change garnets previously reported (K. Schmetzer et al., “Color-change garnets from Madagascar: Variation of chemical, spectroscopic and colorimetric properties, Journal of Gemmology, Vol. 31, No. 5–8, 2009, pp. 258–259). However, these garnets contain a much higher grossular component (16.78%–22.46%) than those reported by Schmetzer et al. (3.02%–10.23% grossular). To our knowledge, the chemical composition of this type of color-change garnet has never been reported before.
The color of the three wafers was quantitatively calculated by using the visible spectra (Z. Sun et al., “Vanadium and chromium bearing pink pyrope garnet: characterization and quantitative colorimetric analysis,” Winter 2015 G&G, pp. 348–369). The color of each wafer can be presented by using CIE L*a*b* and RGB color coordinates, as seen in table 2. The calculated color panels of three wafers under daylight-equivalent lighting (CIE D65 illumination) and incandescent lighting (CIE A illumination) are shown in the bottom row of the figure above. The three wafers were also photographed under both fluorescent light and incandescent light to compare with the panels in the top row.

Table 1: Chemical composition of pyrope-spessartine garnet.

Samples
Wafer 1
Wafer 2
Wafer 3

Path length
3.553 mm
3.138 mm
3.284 mm

Carat weight
2.851 ct
3.706 ct
3.908 ct

Oxide wt.% (1)

CaO
8.46%
7.49%
5.98%

MgO
5.88%
8.25%
7.35%

MnO
25.11%
18.04%
22.73%

FeO
1.53%
3.34%
1.61%

Al2O3
21.72%
22.71%
22.39%

V2O3
0.23%
0.13%
0.24%

Cr2O3
0.06%
0.04%
0.08%

SiO2
36.66%
39.77%
39.11%

TiO2
0.28%
0.13%
0.18%

Total
99.93%
99.90%
99.67%

Cations (2)

Ca
0.7117
0.6074
0.4904

Mg
0.6881
0.9305
0.8387

Mn
1.6688
1.1560
1.4746

Fe2+
0.1003
0.2116
0.1032

Total dodec.
3.1689
2.9055
2.9070

Al
2.0085
2.0248
2.0209

V
0.0146
0.0078
0.0146

Cr
0.0038
0.0023
0.0048

Total oct.
2.0269
2.0348
2.0403

Si
2.8760
3.0094
2.9950

Ti
0.0164
0.0075
0.0102

Total tet.
2.8924
3.0169
3.0052

End member mol.%

Goldmanite
0.72%
0.38%
0.72%

Uvarovite
0.19%
0.11%
0.24%

Spessartine
52.66%
39.79%
50.73%

Pyrope
21.71%
32.03%
28.85%

Almandine
3.17%
7.28%
3.55%

Grossular
21.55%
20.41%
15.92%

Total
100.00%
100.00%
100.00%

1 Average composition of 3 analyses each
2 Calcutated on the basis of 12 oxygens

One way to judge the quality of a color-change stone is to plot the color pair in the CIE 1976 color circle. Good color-change pairings show a large hue angle difference, small chroma difference, and large chroma values (see table 2). The color coordinates of the three wafers were plotted in the CIE 1976 color circle (see below). The color change of this material is not very significant, but is definitely observable.

Table 2: Color-change measurements of pyrope-spessartine garnet.

CIE A illumination
CIE D65 illumination

Wafer 1
			3.553 mm
L*
a*
b*
L*
a*
b*

70.10
6.67
26.35
69.17
-5.26
29.38

R
G
B
R
G
B

199.81
165.74
123.90
178.67
170.09
115.32

Wafer 2
			3.138 mm
L*
a*
b*
L*
a*
b*

74.34
9.98
23.73
72.95
1.23
24.59

R
G
B
R
G
B

216.09
175.18
139.86
197.89
176.80
134.24

Wafer 3
			3.284 mm
L*
a*
b*
L*
a*
b*

69.96
6.90
20.65
69.24
-4.94
23.80

R
G
B
R
G
B

196.99
165.53
134.00
176.48
170.38
125.84

Colorimetric Parameters of Three Garnet Wafers in The CIELAB 1976 Color Circle @chapter:10


Publication Year: 2022 Title: Rare Orange Benitoite Abstract: Figure 1. The size and bright color of this 2.29 ct orange benitoite are exceptionally rare. Photo by Nathan Renfro.
A bright orange benitoite (figure 1) weighing 2.29 ct was recently examined at the Carlsbad laboratory. Standard gemological testing revealed a refractive index of 1.756 to over the limit (OTL) and a specific gravity of 3.68. The fluorescence reaction was strong orange in long-wave ultraviolet light and medium blue in short-wave UV (figure 2). The benitoite was slightly color-zoned orange and blue; the blue portion’s pleochroism was very light blue and darker blue, while the orange portion’s pleochroism was orangy yellow and dark orange. Microscopic examination showed altered crystals with discoid fractures (figure 3) and strong doubling. The discoid fractures were consistent with heated benitoite.

Figure 2. The orange benitoite’s response to long-wave (left) and short-wave UV (right). Photos by Nathan Renfro.

Figure 3. The orange benitoite contained several discoid fractures with healed fringes, consistent with heat-treated benitoite. Photomicrograph by Nathan Renfro; field of view 2.33 mm.
Benitoite is a barium titanium silicate (BaTiSi3O9) known as the California state gem, and it only occurs in gem quality in San Benito County, California. The New Idria District produces medium to medium-dark blue and lighter blue colors. According to a previous study published in G&G, pink and colorless examples are considered rare. In addition, heat treatment of lighter-color or colorless benitoite may result in an orange color. Since only a small portion of the treated material successfully changes color, orange benitoite is considered rare (B.M. Laurs et al., “Benitoite from the New Idria District, San Benito County, California,” Fall 1997 G&G, pp. 166–187).
This benitoite was faceted by Bill Vance of Vance Gems, who stated that the rough was colorless prior to heat treatment. The bright orange color and large size make this an exceptional example of orange benitoite. Very few of these have been examined at GIA, and this 2.29 ct gemstone is the largest example we have observed. @chapter:5


Publication Year: 1992 Title: Spring 1992 Gem News International Abstract: TUCSON ‘92
Diamonds
            Colored Diamonds
Colored Stones
            Unusual Fire Agate
            Fine Amazonite from Brazil
            Baltic Amber More Plentiful
            Faceted Apatites from Madagascar
            African Aquamarine
            Axinite from Russia
            Beryl from Russia
            Chrysocolla-Colored Chalcedony from Mexico
            Commercial "Fantasy" Cuts
            Cat's-Eye Emerald
            Moldavite Plentiful
            Eire Opal from Mexico
            Update on Peridot
            Pietersite from Namibia
            Rubies and Sapphires from Vietnam
            New Ruby Deposit in Namibia
            Australian Ruby
            Rubies and Pink Sapphires from Azad Kashmir, Pakistan
            Ruby in Zoisite
            Chinese Blue Spinel
            Tourmaline from Paraiba, Brazil
            Fine Tourmalines from Africa
            Green Zoisite from East Africa
            Rare Gemstones from Mont St. Hilaire
Enhancements
            Update on Diffusion-Treated Sapphires
            Blue Enhanced Opal
            Irradiated Green Topaz
Synthetics and Simulants
            Synthetic Alexandrite Gets New Name
            More on Hydrothermal Synthetic Beryls
            Colored CZ Plentiful
            Rare Laboratory-Grown Crystals
            Magnetic "Pierceless Earrings"
            Another Chatoyant Glass
            Novel Crystal Opal Imitation
            Faceted Synthetic Quartzes
            Knischka Synthetic Rubies
            Synthetic Blue and Green Sapphires Grown by Czochralski Pulling
            Titanium-Doped Synthetic Pink Sapphire
            Imitations of Sugilite and Other Nontransparent Gems
            Faceted Colored YAG
            YAG as an "Ornamental" Material
Instrumentation
            Instrument for Detecting Diffusion Treatment

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Publication Year: - Title: Celebrating G&G’s 80th Year and the Artistry of Harold and Erica Van Pelt Abstract: View Gallery

	Opening reception for the G&G museum exhibit
On June 11, G&G contributors, supporters, and staff toasted the opening of the new GIA Museum exhibit, “The Beauty of Science: Gems & Gemology Celebrates 80 Years, Featuring the Artistry of Harold and Erica Van Pelt.” The exhibit spotlights gems and jewelry featured on selected G&G covers since 1981. The cover photos are the work of the Van Pelts, the husband-and-wife team who contributed nearly three decades of photography to the journal’s pages. In addition to gathering treasures from the Smithsonian and other sources, the collection offers intriguing examples of cutting-edge research, locality reports, and industry coverage over the years. The exhibit runs through December 14. @chapter:26