# Publication Year: 2020
# Title: Sunstone Plagioclase Feldspar from Ethiopia
# Abstract: Figure 1. Left: Forty-four Ethiopian rough sunstones exhibiting different colors and clarities. The largest stone weighs 54.41 ct. Right: Four Ethiopian rough sunstones ranging from 9.92 to 35.42 ct. All 48 rough stones were identified as labradorite by LA-ICP-MS, except for one spot as bytownite. Photos by Diego Sanchez (left) and Shunsuke Nagai (right).
Ethiopia, traditionally known for opal, has become an important source for emerald and sapphire. After these significant discoveries, a new type of Cu-bearing sunstone feldspar, first shown in 2015 to Tewodros Sintayehu (Orbit Ethiopia Plc.), was discovered in the Afar region (L. Kiefert et al., “Sunstone labradorite-bytownite from Ethiopia,” Journal of Gemmology, Vol. 36, No. 8, 2019, pp. 694–695). This material made its way to the jewelry market last year in Tucson.
To fully characterize this new production, GIA obtained 48 Ethiopian sunstones for scientific examination. Among them, 44 rough stones (figure 1, left) were borrowed from Stephen Challener (Angry Turtle Jewelry), who acquired them from an Ethiopian gem dealer in Tucson in February 2019. Another four rough stones (figure 1, right) were purchased by author YK from Amde Zewdalem (Ethiopian Opal and Minerals) and Benyam Mengistu, who facilitates mining and exporting samples from Ethiopia, at the Tokyo International Mineral Association show in June 2019. Prior to this discovery, the only verified occurrences of Cu-bearing feldspar were from Lake and Harney Counties in Oregon (e.g., the Dust Devil and Ponderosa mines). However, more than a decade ago there was a controversy about Cu-bearing feldspar on the market purportedly from Asia or Africa with an undetermined color origin, presumably Cu-diffused (G.R. Rossman, “The Chinese red feldspar controversy: Chronology of research through July 2009,” Spring 2011 G&G, pp. 16–30; A. Abduriyim et al., “Research on gem feldspar from the Shigatse region of Tibet,” Summer 2011 G&G, pp. 167–180). Gemological testing and advanced analytical methods helped distinguish this new Ethiopian material from the Oregon material and the controversial feldspar of questionable color origin mentioned above in order to ensure GIA’s accurate reporting of the natural origin of Cu-bearing feldspar.

Figure 2. Left: Clouds of copper platelets were observed in numerous Ethiopian sunstones. Field of view 3.13 mm. Center: Dense networks of reddish wispy dislocations were seen in some Ethiopian sunstones, along with a slightly greenish blue bodycolor. Field of view 2.72 mm. Right: Yellowish crystals of what are likely fayalite were seen in one Ethiopian feldspar. These inclusions have also been documented in Oregon sunstone. Field of view 2.82 mm. Photomicrographs by Nathan Renfro.
Two polished rough Ethiopian samples gave RI readings of nα = 1.562 and nγ = 1.571 and birefringence of 0.009. Optic signs were biaxial positive. Hydrostatic SG measurements were 2.70 and 2.72. These RI and SG ranges overlapped with Oregon sunstone (RI—nα = 1.560–1.570, nγ = 1.568–1.579; birefringence—0.006–0.012; SG—2.70–2.72) but were significantly higher than other Cu-bearing feldspars with undetermined natural or treated color origin (nα = 1.551–1.559, nγ = 1.559–1.566; birefringence—0.004–0.010; SG—2.68–2.69). A total of 18 Ethiopian sunstones were tested under a desktop UV lamp. Eleven showed very weak orange fluorescence, while seven were inert under long-wave UV. All showed very weak red fluorescence under short-wave UV. Under magnification, many showed dense clouds of reflective copper platelets, much like those observed in material from Oregon (figure 2, left). Some stones also showed an interesting wispy network of reddish dislocation stringers with a greenish blue bodycolor in transmitted light (figure 2, center). Another example revealed several yellow crystals of what appeared to be fayalite, an inclusion also observed in Oregon sunstone (figure 2, right).

Figure 3. Chemical comparison of Oregon and Ethiopian sunstone and Cu-bearing feldspar with undetermined color origin. Mg (A and C) is the key trace element that separates Ethiopian from Oregon sunstone. The unknown Cu-bearing feldspar has a much higher Cu and Sr concentration than other natural untreated sunstones (A, D, E, and F). For major elements, Ethiopian sunstone overlaps with Oregon sunstone, with a slight lower Ca concentration (B and D). The unknown Cu-bearing feldspar contains more Na and less Ca than other natural untreated sunstones (B, D, and F).

Figure 4. Illustration of solid solution in the feldspars, modified after Deer et al. (Rock-Forming Minerals, Volume 4: Framework Silicates, 1963). The nomenclature of the plagioclase series and the alkali feldspars is also shown. All 48 Ethiopian rough stones (yellow dots) were classified as labradorite except one bytownite. Forty-five Oregon sunstones (blue and green dots) were classified as labradorite-bytownite. Twenty Cu-bearing feldspars with undetermined color origin (red dots) were classified as andesine-labradorite. Ethiopian sunstones are less calcic than Oregon sunstones. Variation of refractive indices ng and specific gravity with composition of feldspars were plotted in the ternary plot as pink and blue straight lines, respectively. Note: nγ = gamma, the highest RI of a biaxial crystal, light vibrating parallel to the Z optical direction.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was used to measure the chemistry of all 48 Ethiopian sunstones, 26 Dust Devil sunstones, 19 Ponderosa sunstones, and 20 Cu-bearing feldspars with undetermined color origin. NIST 610 and USGS GSD-1G and GSE-1G glasses were used as external standards. 29Si was used as an internal standard. Ponderosa and Dust Devil sunstones yielded an end member composition of Ab28–32An67–72 Or0.3–0.4 and Ab28–36An64–72Or0.3–0.8, respectively (table 1). They are classified as labradorite-bytownite using an albite-anorthite-orthoclase (Ab-An-Or) ternary diagram (figures 3B and 4, blue and green dots). Ethiopian sunstones yielded an end member composition of Ab30–39An60–70 Or0.4–1.4, which is generally similar but less calcic than Oregon sunstones (table 1). All analyses of Ethiopian material indicated classification as labradorite except one spot that gave bytownite (figure 3B and figure 4, yellow dots). The Cu-bearing feldspar with undetermined color origin yielded an end member composition of Ab46–51An46–51Or2–3 (table 1). They were classified as andesine-labradorite, distinct from the Oregon and Ethiopian material (figure 3B and figure 4, red dots). In addition to the differences with major elements Na, Ca, and K, the analyses revealed that the trace elements Mg, Cu, Ga, and Sr were the four best discriminators providing clear separations among Oregon and Ethiopian sunstone and Cu-bearing feldspar with undetermined color origin. All Ethiopian sunstone had a lower Mg concentration (261–686 ppmw, table 1) than Oregon sunstone (>810 ppmw, table 1) (figure 3A). The Cu-bearing feldspar with undetermined color origin had a higher Cu (>405 ppmw) and Sr (>1120 ppmw) concentration than Oregon and Ethiopian sunstone (figure 3, A, D, E, and F). Interestingly, Ponderosa samples (figure 3, C and E) had a lower Ga concentration (<14.0 ppmw) than the Ethiopian sunstone and Cu-bearing feldspar with undetermined color origin. A group of Dust Devil stones with higher Mg, Ga, and Sr concentrations were separated from all other sources in figures 3A and 3C, further differentiating them from Ponderosa stones.
Copper-bearing sunstones from different sources are visually indistinguishable from one another. Gemological properties are usually sufficient to separate Ethiopian and Oregon sunstones from these Cu-bearing feldspars with undetermined color origin. However, accurate major and trace element chemical analysis obtained by methods such as LA-ICP-MS, XRF (Ga and Sr were first identified as reliable discriminators for separating Ethiopian from Oregon sunstones using XRF by author GRR before this work), or electron microprobe is critical to separating Ethiopian, Oregon, and Cu-bearing feldspar with undetermined color origin. @chapter:14 @chapter:0 @chapter:14


# Publication Year: 2019
# Title: Color-Change Spessartine Garnet: A First Report
# Abstract: Figure 1. Color-change phenomenon was observed in this 2.11 ct octagonal mixed-cut spessartine. The left image, with a dark green color, was taken using an LED light source with 6500K color temperature (a daylight-equivalent light simulator). The right image, showing a dark red color, was taken with an LED light source with 2700K color temperature (an incandescent light simulator). Photos by Robison McMurtry and Diego Sanchez.

GIA’s Carlsbad laboratory recently examined a 2.11 ct faceted stone (figure 1) that showed strong color change from dark green under daylight-equivalent lighting to dark red under incandescent illumination. Standard gemological testing revealed a refractive index that was over the 1.80 RI limit of the GIA desktop refractometer. This was the first example of a color-change garnet with an over-the-limit RI reading examined by GIA. Fluorescence was inert to long-wave and short-wave UV light. The stone did not show any pleochroism with the dichroscope. Using a handheld spectroscope, we observed a cutoff at about 460 nm and a broad band centered at about 575 nm. Microscopic examination revealed only a small fracture and strong internal strain. High-order interference colors were observed in cross-polarized light from the strain along grain boundaries.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) results showed that the stone was composed predominantly of spessartine (80.37 mol.%), with minor contributions from other end members of the garnet species (see supplementary table 1). It is classified as a spessartine garnet based on the criteria in the pyrope-spessartine-almandine ternary diagram (figure 2, left) modified from Stockton and Manson (“A proposed new classification for gem-quality garnets,” Winter 1985 G&G, pp. 205–218). The RI and SG could also be calculated based on chemical composition (W.A. Deer et al., Rock-Forming Minerals: Orthosilicates, Vol. 1A, Geological Society of London, 1982, pp. 485–488). The calculated RI and SG—plotted in figure 2, right—were 1.797 and 4.182, respectively. The calculated RI value was consistent with the measured RI value. In 2001, Krzemnicki et al. reported a garnet composed of 76.9 mol.% spessartine and 4.2 mol.% goldmanite with a color change from orange-yellow under daylight-equivalent lighting to reddish orange under incandescent illumination based on the colorimetric data in the article, although color change from brownish green to brownish was observed visually (“Colour-change garnets from Madagascar: Comparison of colorimetric with chemical data,” Journal of Gemmology, 2001, Vol. 27, No. 7, pp. 395–408). The high spessartine and goldmanite composition of the stone is similar to our stone reported here, but with much weaker color change.

Figure 2. Left: Three LA-ICP-MS data points, calculated based on molecular percentages for pyralspite garnet, were plotted in a pyrope-spessartine-almandine ternary diagram (modified after Stockton and Manson, 1985). Refractive index and spectral boundaries were used to distinguish among the six proposed garnet gem species labeled in the diagram. Right: The same data points were further plotted in the pyrope-spessartine-almandine RI-SG diagram (modified after Deer et al., 1982) to validate the measured over-the-limits RI.
To understand why this spessartine garnet showed a color-change phenomenon, we collected an ultraviolet/visible/near-infrared (UV-Vis-NIR) spectrum (the visible portion of the spectrum is shown in figure 3), which was then used to quantitatively calculate the stone’s colorimetric coordinates (L*, a*, and b*; see table 2 at www.gia.edu/gems-gemology/summer-2019-labnotes-color-change-spessartine-garnet-icp-table2.pdf) under different lighting conditions. The strong absorption below 450 nm is caused by Mn2+ (R.K. Moore and W.B. White, “Electronic spectra of transition metal ions in silicate garnets,” Canadian Mineralogist, Vol. 11, No. 4, 1972, pp. 791–811). A wide absorption band centered at about 585 nm is caused mainly by V3+ (C.A. Geiger et al., “Single-crystal IR- and UV/VIS-spectroscopic measurements on transition-metal-bearing pyrope: the incorporation of hydroxide in garnet,” European Journal of Mineralogy, Vol. 12, No. 2, 2000, pp. 259–271), which produced two transmission windows: one in the blue-green part of the spectrum (figure 3, window A) and the other in the red (figure 3, window B). This was the cause of the color change in this spessartine garnet, as incandescent illumination highlighted the red transmission window and daylight-equivalent lighting highlighted the blue-green window. Color pairs under CIE D65 illumination (representing daylight-equivalent lighting) and CIE A illumination (representing incandescent illumination) were calculated and are shown in figure 3, above transmission window A and B. The darker color pair (top row), directly calculated from the measured UV-Vis-NIR spectrum, closely matched the dark appearance of the stone (again, see figure 1) with L*(lightness) around 14.5. It was the strong absorption generated by very high Mn and V concentration, along with the stone’s relatively large size, that produced a long light path length. To better observe the saturation and hue of the color pair, the authors changed the L*to 50 and reproduced the color pair with the same a*and b*values (bottom row). The hue difference of the color pair is easier to see with increased lightness.

Figure 3. In the visible absorption spectrum of the stone, transmission window A is centered at 510 nm, while transmission window B is between 630 and 650 nm. The strong absorption below 450 nm is caused by Mn2+; a wide absorption band between 550 and 650 nm is caused mainly by V3+. The stone had so much Mn that the detector of the instrument was saturated below 440 nm. Calculated color pairs, representing the color of the stone seen under CIE D65 illumination and CIE A illumination, are shown above the two transmission windows. The human eye is not color sensitive above 650 nm or below 420 nm (both represented in the graph by the gray color zoning). The transmission in these wavelength ranges cannot be perceived effectively.

One way to judge the quality of a color-change stone is to plot the color pair in the CIELAB 1976 color circle. Good color-change pairings show a large hue angle difference, small chroma difference, and large chroma values (Z. Sun et al., “How to facet gem-quality chrysoberyl: Clues from the relationship between color and pleochroism, with spectroscopic analysis and colorimetric parameters,” American Mineralogist, Vol. 102, No. 8, 2017, pp. 1747–1758). The color coordinates L*, a*, and b*(again, see table 2) of the stone under CIE D65 illumination and CIE A illumination were plotted in the CIELAB 1976 color circle in figure 4. The spessartine showed a low saturation under CIE A illumination.

Figure 4. In the CIELAB 1976 color circle, the color of the stone changes from medium saturated green under CIE D65 illumination to low saturated orangy red under CIE A illumination, with a hue angle difference of 79.11°, a chroma difference of 9.25, and a color difference of 15.82. Full sets of L*, a*, b* and RGB color coordinates are shown in table 2.
Color change has been reported previously in pyrope-spessartine (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. 235–282), in pyrope (Z. Sun et al., “Vanadium- and chromium-bearing pink pyrope garnet: characterization and quantitative colorimetric analysis,” Winter 2015 G&G, pp. 348–369), and in grossular (Spring 2018 GNI, pp. 233–236). To the authors’ knowledge, this was the first color-change spessartine reported. @chapter:26 @chapter:0 @chapter:26


# Publication Year: 2019
# Title: Resin-Coated and Clarity-Enhanced Aquamarine Pendant
# Abstract: Figure 1. This 34.24 ct light greenish blue free-form aquamarine pendant, measuring 33.40 × 25.75 × 6.40 mm, was seen in the Carlsbad laboratory. Photo by Robison McMurtry. Stone courtesy of Stephen Challener.

The Carlsbad laboratory received a 34.24 ct light greenish blue free-form pendant (figure 1) measuring 33.40 × 25.75 × 6.40 mm. One side of the pendant was flat and polished, and the other side had a rough surface. Standard gemological testing gave a refractive index (RI) of 1.570–1.580. The pendant had the same reaction to long-wave and short-wave UV light: blue fluorescence in the center and green fluorescence around the edges of the stone. Examination with a standard gemological microscope revealed a blue and orange flash effect most clearly visible from the flat side (figure 2, left), which is diagnostic of clarity enhancement. Ultraviolet/visible/near-infrared (UV-Vis-NIR) spectra were consistent with natural aquamarine, with absorption peaks at 370 and 425 nm and an absorption band at ~830 nm (figure 2, right). Raman spectroscopy showed the presence of polymer on the rough side of the stone and aquamarine on the polished flat side. Although emeralds are the variety of beryl most commonly associated with clarity enhancement, filled aquamarine has previously been reported in the Chinese market (J. Li et al., “Polymer-filled aquamarine,” Fall 2009 G&G, pp. 197–199).

Figure 2. Left: The orange and blue flash effect seen in a clarity-enhanced fracture of the aquamarine. Photomicrograph by Michaela Stephan; field of view 4.24 mm. Right: The UV-Vis-NIR spectrum, with absorption peaks at 370 and 425 nm and an absorption band at ~830 nm, is consistent with natural aquamarine.

Figure 3. Left: Gas bubbles and high luster on the aquamarine’s resin-coated rough surface, shown near the drill hole. Photomicrograph by Michaela Stephan; field of view 7.19 mm. Right: The FTIR spectrum shows polymer peaks at ~3100–2850 cm–1. The dotted line is the spectrum of an untreated aquamarine, shown for reference.
Only one side, the rough side, was coated with polymer resin. Viewed in the microscope, this side appeared to have a thin transparent layer on the surface. Trapped air bubbles were visible with magnification (figure 3, left), and areas with the coating had a higher luster than the polished flat side. Fourier-transform infrared (FTIR) spectroscopy taken from the rough side revealed strong diagnostic peaks at ~3100–2850 cm–1 (figure 3, right).
Although clarity enhancement and coating of beryl gemstones are not uncommon, this material is rarely seen in a gemological laboratory. Both treatments are readily identified, but careful examination of every stone is important to identify them. @chapter:19 @chapter:0 @chapter:19


# Publication Year: 2018
# Title: Futurescape Forum
# Abstract: The 2018 Symposium’s finale, the Futurescape Forum, brought together six industry leaders in a panel discussion moderated by Dr. David Ager, managing director of executive development at the Harvard Business School. The panelists were Bruce Cleaver, CEO of the De Beers Group; Gina Drosos, CEO of Signet Jewelers; Jason Goldberger, CEO of Blue Nile; Andy Johnson, CEO of Diamond Cellar Holdings; Rahul Kadakia, international head of jewelry at Christie’s; and Kent Wong, managing director of Chow Tai Fook.
The forum began with an industry forecast via video from Scott Galloway of the NYU Stern School of Business. The discussion centered around several key points:

Technologically driven changes in retailing and trading, and continued consolidation across the value chain. These market shifts include challenges from giants such as Amazon and an increase in manufacturers selling direct to consumers, bypassing traditional retail channels.
Evolving consumer tastes and desires, including concerns over gem sources and sustainable production
The need to appeal to a rapidly changing workforce
Disruption caused by laboratory-grown diamonds, both in the marketplace and in laboratory testing and identification

Bruce Cleaver of the De Beers Group listens as Signet Jewelers’ Gina Drosos explains the importance of omni-channel retailing. Photo by Denise Conrad/GIA.
TECHNICAL CHALLENGES
There was broad agreement that retailers must adapt to technology, not just in sales channels, but in ways it can help individualize each customer.
Drosos explained that omni-channel retailing is a necessity because customers routinely cross channels in their shopping experience, starting online and ending in the store. Online channels can enhance the in-store experience by making it possible for customers to make appointments online—90% of such appointments result in a sale, she noted.
Wong said that 15% of Chow Tai Fook’s sales by volume are done online, but mainly in small gold items and in charms such as Hello Kitty and Disney characters. At the high end, Kadakia said that 90% of Christie’s auction business is still done by traditional bidding, but the remainder is online, mainly from younger clients buying pieces under $10,000. “This is how we target younger customers,” he said.
A CHANGING WORKFORCE
The changing workforce was a key discussion point in the session. Businesses must adapt to a millennial workforce comprised of people who switch careers because they value diverse experiences and often do not want to stay with a company over the long term.
Goldberger told the audience that organizations should not become too insular and that people with diverse backgrounds bring new thinking. He added, “The reality of today is that tech people move every two or three years, so we have a choice: Do we lose them entirely or benefit from their talent while they are here?”

An audience member poses a question for the panel at the Futurescape Forum. Photo by Denise Conrad/GIA.
Cleaver noted that there are excellent opportunities to diversify the traditionally conservative diamond industry, while Wong said his company brings in gifted designers by offering them a platform to create and sell their designer pieces. “Talented people need that freedom,” he pointed out. Johnson added that not everyone wants to switch careers, and businesses must adapt to workers who cannot be on hand full-time.
NATURAL AND LABORATORY-GROWN DIAMONDS
Laboratory-grown diamonds occupied a great deal of discussion in the Futurescape Forum. Panelists agreed that while they have a place in the market, natural diamonds will still be the choice to celebrate life’s landmark occasions. Kadakia was confident that natural diamonds will remain the consumer choice because they will always have value, while synthetics will not hold value over time.
Goldberger noted that while today’s engagement ring buyers invariably prefer natural diamonds, we cannot take this for granted in the future. He cited the example of consumers who in the 1990s loved to browse bookstores but then deserted them for online channels. Cleaver said that synthetic diamonds’ place in the market was firmly in the “fun and fashion” side.
GEMSTONE SOURCING AND PRODUCTION
Cleaver also related the economic and political success of Botswana, once one of the world’s poorest nations. Diamond revenues, coupled with good governance, helped transform Botswana into one of Africa’s most prosperous countries.
As Cleaver noted, “It’s a story not always told—the good that diamonds can do in employing people and development.” Drosos said customers are interested in knowing the origins of their diamonds and that Signet is working to familiarize all employees with its corporate social policies regarding sourcing.

Kent Wong discusses Chow Tai Fook’s approach to attracting talented designers while David Ager (left) and Rahul Kadakia (right) look on. Photo by Denise Conrad/GIA. @chapter:32 @chapter:3 @chapter:32


# Publication Year: 1982
# Title: Gemstones of Pakistan: Emerald, Ruby, and Spinel
# Abstract: Only during the last few years have the gem riches of Pakistan become known to the rest of the
world. This article reports on three gem materials currently being mined: emerald, corundum (most importantly, ruby), and spinel. Intensely colored emerald crystals occur in dolomitic talc schists in the Swat Valley. Unusually high optical properties and density serve to distinguish these emeralds from those found elsewhere. Numerous gas-liquid inclusions are also typical. In the Hunza Valley, specimen and gem-quality crystals of corundum and spinel occur in beds of marble enclosed in gneisses and mica schists. The gemological properties of the Pakistan rubies and sapphires vary only slightly within normal limits. @chapter:1 @chapter:0 @chapter:1


# Publication Year: -
# Title: Photoluminescence Review and Gem Material from Unusual Locales in the Spring 2016 G&G
# Abstract: This issue features G&G’s coverage of the 2016 Tucson gem and mineral shows. The cover photo shows Brian Cook’s Wheel of Light numinous pendant, which received first place in the AGTA Spectrum Awards’ Fashion Forward category. To create the pendant, Mr. Cook drilled a channel into the apex of an 825 ct quartz disk and inserted rough crystals of Paraíba tourmaline, haüyne, ruby, and spessartine garnet. The colors of these crystals are seen as concentric rings. A 24K gold setting, braided leather straps, a rutilated quartz length adjuster, and fire agate beads complete the piece. Photo by Robert Weldon/GIA, courtesy of Brian Cook (Nature’s Geometry).

	The Spring 2016 issue of Gems & Gemology explains the relevance of photoluminescence to the diamond trade and reports on Australian chrysoberyl, emerging production of Italian serpentine and Tajik variscite, the treatment processes used to create “pistachio” cultured pearls, and the recent Tucson gem shows.

	An Introduction to Photoluminescence Spectroscopy for Diamond and Its Applications in Gemology

	The lead article in this issue, by GIA’s Christopher M. Breeding and Sally Eaton-Magaña, reviews the physics and methodology of photoluminescence. This analytical technique is increasingly important in the separation of treated and synthetic diamonds from natural material, and the authors explain how it helps ensure proper disclosure of growth processes and treatments within the trade.

Diamonds can show a wide range of hues and fluorescence colors. GIA regularly uses photoluminescence spectroscopy to confirm the natural origin of such diamonds. Photoluminescence is a sensitive technique that allows one to characterize the atomic-level lattice defects that act as a fingerprint of the growth and possible treatment history of diamonds; this method is based on similar principles as the observed fluorescence. Photos of a portion of the Aurora Butterfly of Peace by Robert Weldon.

	Chrysoberyl Recovered with Sapphires Related to Tertiary Volcanics in the New England Placer Deposits, New South Wales, Australia

	German researcher Karl Schmetzer and his coauthors investigate chrysoberyl crystals from the sapphire placer deposits of Australia’s New England gem fields. Using various chemical and mineralogical properties to divide the materials into four specific subgroups, the authors explore various aspects of the material, including its unique sectorial color zoning, pleochroism, and chatoyancy.

	While some of the chrysoberyl research samples from the sapphire placer deposits in the New England area were faceted, others were cut as cabochons, showing chatoyancy. The cat’s-eye cabochons range from 1.34 ct (6.5 × 5.9 mm) to 0.64 ct (5.1 × 4.7 mm). Photo by K. Schmetzer.

	Gem-Quality Serpentine from Val Malenco, Central Alps, Italy

	A team of researchers, led by Ilaria Adamo of the Italian Gemological Institute in Milan, examines serpentine obtained from Pizzo Tremogge  a source located in the Central Alps of Italy. Spectroscopy and chemical analysis confirm the main phases of the serpentine group. In particular, the presence of antigorite indicates metamorphism at high temperatures, providing insight into the geological and petrological history of the Val Malenco region.

	Identification of “Pistachio” Colored Pearls Treated by Ballerina Pearl Co

	Chunhui Zhou and his GIA colleagues perform a number of experiments on cultured pearls from P. margaritifera treated by Ballerina Pearl Co. to mimic the pistachio hue that naturally occurs in some specimens. The authors look for indicators to separate naturally colored from treated material and eliminate bleaching as a possible treatment process.

Eight natural-color pistachio pearls ranging from 9.70 × 9.40 mm to 15.00 × 12.30 mm, produced by black-lipped pearl oysters, were examined in this study. Photo by Sood Oil (Judy) Chia.

	Variscite from Central Tajikistan: Preliminary Results

	Researchers led by Andrey Litvinenko (Russian State Geological Prospecting University, Moscow) investigate the production of cabochon-grade variscite from a relatively unknown deposit in Tajikistan. While further study is required, initial results reveal the presence of relatively high levels of arsenic and sulfur that may link this source to an inactive antimony deposit located nearby.

	Lab Notes

Lab Notes in the Spring issue include a report on the largest blue HPHT synthetic diamond examined at a GIA lab, an unusual emerald/emerald doublet submitted to the Tokyo lab, and the first mounted CVD synthetic melee diamond identified by GIA.

	Micro-World

Micro-World continues to reveal the inner mysteries of gemstones through photomicrography. The section features pieces on svanbergite inclusions in dolomite from British Columbia, orange platelets creating iridescence in scapolite, and visible phase changes in a Sri Lankan sapphire.

	Gem News International

G&G’s annual coverage of the Tucson gem shows, featuring fine colored stones from around the world, kicks off this issue’s Gem News International section. Other entries cover colorless HPHT synthetic diamonds weighing to up 3.5 ct from China, polymer-treated hessonite, and a new sapphire rush near Vohitany, Madagascar.

	This 31.34 ct bicolor tourmalines pin, which contains gemstones exclusively from the Stewart Lithia mine in San Diego County, has an emotional connotation for the artist. Photo by Robert Weldon/GIA; courtesy of Paula Crevoshay.

	Also in this issue are the winners of the Dr. Edward J. Gübelin Most Valuable Article Award, along with the 2016 Gems & Gemology Challenge quiz. Response cards and online entries for the Challenge must be submitted by Friday, August 5, 2016. @chapter:52 @chapter:1 @chapter:52


# Publication Year: 2023
# Title: Bright Orange Sapphire from Greenland
# Abstract: Figure 1. A 1.28 ct heated pink round brilliant sapphire. Photo by Robert Weldon; courtesy of Greenland Ruby.
The Aappaluttoq mine in Greenland is home to the oldest known ruby-bearing rocks on Earth. These host rocks are nearly three billion years old (A. Polat et al., “New age (ca. 2970 Ma), mantle source composition and geodynamic constraints on the Archean Fiskenæsset anorthosite complex, SW Greenland,” Chemical Geology, Vol. 277, No. 1-2, 2010, pp. 1–20). This deposit was initially known for producing translucent to opaque ruby and pink sapphire, much of it cut into cabochon form. However, transparent material has always been found in this mine and makes up about 5–10% of the production.

Figure 2. A 0.89 ct heated orange oval brilliant sapphire. Photo by Robert Weldon; courtesy of Greenland Ruby.
At the AGTA show, Greenland Ruby displayed many examples of attractive transparent ruby and pink to orangy pink sapphire, including several fancy-color sapphires in sizes greater than one carat (figure 1; see also a color study of fancy sapphire from Greenland in this issue). These fancy colors are achieved by heat treating nearly colorless to slightly pink transparent material. A transparent bright orange sapphire weighing 0.89 ct and measuring 6.41 × 5.02 mm (figure 2) immediately caught our eye. Martin Viala, product manager for Greenland Ruby, shared with us a video of the original 1.07 g sapphire rough (see below). This unusual stone was mined in late 2019 and heated in May 2022. Viala noted that it was a textbook example of a chromium trapped-hole (h●–Cr3+) chromophore (E.V. Dubinsky et al., “A quantitative description of the causes of color in corundum,” Spring 2020 G&G, pp. 2–28).

	Orange Sapphire Rough from Greenland Ruby @chapter:5 @chapter:0 @chapter:5


# Publication Year: 2015
# Title: Crimson Prince Ruby from Namya
# Abstract: The 3.32 ct Crimson Prince ruby was cut from a 1.2 gram rough. Both the color and the clarity make this stone extremely rare. Photo by Robert Weldon/GIA, courtesy of Jeffery Bergman.

Mogok, Myanmar is considered the source of the finest rubies on Earth. In 2000, an exciting new ruby discovery was made in Namya, located in the Kachin state approximately 300 km north of Mogok and east of the jade mine at Hpakant (figure 1). While known mostly for its vibrant pink and red spinels, Namya also produces fine rubies, typically of medium saturation. Due to the remarkably similar geology of the two deposits, it is often impossible to separate Mogok rubies from Namya material.

Figure 1. The Namya mining area is about 300 km north of Mogok. Namya, Mogok, and
Mong Hsu together form a “ruby triangle” in northern Myanmar, as these three locations
have produced high-quality ruby. Adapted from R. Hughes, Ruby & Sapphire: A Collector’s
Guide, 2014, Gem and Jewelry Institute of Thailand, Bangkok, p. 132.
In the spring of 2014, a rough stone with strong red color and unusually fine clarity weighing approximately 1.2 grams was discovered in Namya. The stone was entrusted to a skilled and experienced ruby cutter, who finished it as a 3.32 ct roundish cushion measuring 7.99 mm in diameter. The color, clarity, and cutting are so unusual for a ruby that on initial casual observation, most experts have mistaken it for a spinel.

In December 2014, Richard Hughes of Lotus Gemology examined the stone, commenting on its “pigeon’s blood” color. Additionally, he remarked that its clarity was “extraordinary,” mentioning that only “a light dusting of silk is evenly distributed across the stone” and noting that it was “obvious that the lapidary took great care in its fashioning, befitting a gem of such high value….”

This exceptional ruby deserved a befitting name. Several ideas were put forward; calling it a “King” seemed grandiose, and it was too vividly saturated to be a “Princess.” In March 2015, the Crimson Prince ruby found a fitting new home at a prestigious haute joaillerie on Place Vendôme in Paris. @chapter:51 @chapter:0 @chapter:51


# Publication Year: 1994
# Title: Fall 1994 G&G Lab Notes
# Abstract: Ceramic Statue
Large "Knot" in Citrine
Americium-Treated Green Diamond
Unusual Triangular Inclusion in a Diamond
Grossular-Diopside Rock
Iron-Rich Hornblende
Exceptionally Translucent Jadeite Jade Necklace
Jadeite Jade with Impregnating Substance in Drill Hole
"Banded" Natural-Colored Natural Pearl
Color-Treated Cultured Pearl
Natural-Color Sapphire with Unusual Fluorescence
Color-Zoned Synthetic Sapphire
Serpentine and Forsterite Rock
Detecting Impregnated Turquoise

To view the full section, download the PDF above. @chapter:18 @chapter:0 @chapter:18


# Publication Year: 2022
# Title: Large Faceted Pallasitic Peridot
# Abstract: Figure 1. The face-up view of a 2.32 ct faceted pallasitic peridot, the largest extraterrestrial peridot seen at GIA to date. Photo by Diego Sanchez.

Figure 2. Left: Planar, brownish red thin films are a distinctive inclusion in pallasitic peridot; field of view 1.26 mm. Right: Coarse fingerprints are a common inclusion in both terrestrial and extraterrestrial peridot; field of view 1.99 mm. Photomicrographs by Britni LeCroy.
Peridot, the green gem variety of the mineral olivine, is a relatively common gemstone known for forming as irregular nodules in lava flows or as large crystals within pockets of solidified rock throughout many areas of the world. Rarely, this stone can also be sourced from stony iron meteorites that have survived their flaming passage through Earth’s atmosphere. These peridot-containing meteorites are known as pallasite, and the gems they contain are known as pallasitic peridot. Due to the extreme conditions endured by extraterrestrial stones, examples of faceted pallasitic peridot usually weigh less than half a carat (A.H. Shen et al., “Identification of extraterrestrial peridot by trace elements,” Fall 2011 G&G, pp. 208–213). A recent submission to the Carlsbad laboratory saw the largest client-submitted example to date at 2.32 ct (figure 1). The gem possessed characteristic inclusions such as thin, stacked red platelets (figure 2, left) and coarse, high-relief fingerprints (figure 2, right).

At GIA, extraterrestrial peridot is distinguished from the terrestrial variety by either energy-dispersive X-ray fluorescence or laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis of the trace elements vanadium, lithium, nickel, manganese, zinc, and cobalt (Shen et al., 2011). LA-ICP-MS analysis of these elements in the stone was diagnostic of pallasitic peridot when compared to published terrestrial and extraterrestrial data (Shen et al., 2011) (table 1).
Pallasite is named in honor of geologist Peter Simon Pallas, who first documented a stony iron meteorite with “rounded and elongated drops of a very brittle but hard, amber-yellow, transparent glass” discovered in Krasnoyarsk, Siberia, in 1749. At the time, suggestion of an extraterrestrial origin was daring. However, this theory gained support, and by 1794 additional scientific publications accepted the idea (J. Sinkankas et al., “Peridot as an interplanetary gemstone,” Spring 1992 G&G, pp. 43–51). Today, pallasite is believed to have formed within asteroids containing an iron-nickel core and a silicate mantle (R.T. Dodd, Meteorites: A Petrologic-Chemical Synthesis, Cambridge University Press, Cambridge, UK, 1981, 368 pp.). @chapter:0 @chapter:0 @chapter:0


# Publication Year: 2013
# Title: Scheelite and Hübnerite Inclusions in Quartz from China
# Abstract: Figure 1. Quartz with scheelite and hübnerite inclusions from China, 2.3 cm wide, in daylight (left) and under short-wave UV light (right). Photos by Jaroslav Hyršl.

              Scheelite, a very popular mineral among collectors, is very rarely found as an inclusion in quartz (J. Hyršl and G. Niedermayr, Magic World: Inclusions in Quartz, Bode Verlag, Haltern, Germany, 2003, p. 147). One such quartz specimen, measuring 4.5 cm high and with very high luster (figure 1, left), was collected in 2010 from the famous tungsten deposit at Yaogangxian in Hunan Province, China.

	Figure 2. Two scheelite crystals in quartz, image width 2 mm. Photomicrograph by Jaroslav Hyršl.
The specimen contained about 25 small pseudo-octahedral crystals up to 2 mm with an adamantine luster. Most of the crystals were black, but some were colorless. Under long-wave UV light, both crystal types are inert;  under short-wave UV light, the colorless crystals showed a strong bluish fluorescence, indicating scheelite (figure 1, right). Nevertheless, the black crystals were not fluorescent and their edges were red-brown, a typical color for Mn-rich members of the wolframite group, (Fe, Mn)WO4. Raman testing (by Prof. Albert Gilg, Technical University of Munich) identified colorless crystals as scheelite (figure 2) and black crystals as the mineral hübnerite (figure 3), with the strongest peak at 877 cm–1. Their pseudo-octahedral form confirmed their origin as a pseudomorph after scheelite.

	Figure 3. This group of scheelite crystals in quartz was partially replaced by hübnerite.  Photomicrographs by Jaroslav Hyršl; image width 3 mm. @chapter:15 @chapter:0 @chapter:15


# Publication Year: 1998
# Title: Summer 1988 G&G Book Reviews
# Abstract: “American Jewelry”
By Penny Proddow and Debra Healy, 208 pp., illus., publ. by Rizzoli, New York, 1987. US$75.00

“Introduction to Lapidary”
By Pansy Kraus, 196 pp., illus., publ. by Chilton Book Co., Radnor, PA, 1987. US$19.95

“Jet”
By Helen Muller, 149 pp., illus., publ. by Butterworths, Great Britain, 1987. US$29.95

“Amber”
By Helen Fraquet, 176 pp., illus., publ. by Butterworths, Great Britain, 1987. US$29.95

To view the full section, download the PDF above. @chapter:25 @chapter:2 @chapter:25


# Publication Year: 2023
# Title: Luminescent Synthetic Garnet-Like Crystals
# Abstract: Figure 1. Yellow to greenish yellow faceted cerium-doped YAG “lumogarnets” ranging from 4 to 12 ct apiece. Photo by Lisa Kennedy; courtesy of Turtle’s Hoard.
At the 22nd Street show, the author spoke with Tim Challener of Turtle’s Hoard (Raleigh, North Carolina), who was selling some unique rough and faceted luminescent synthetic garnet-like crystals, which he referred to as “lumogarnets.” After 12 years in the gem business, Turtle’s Hoard began selling only laboratory-made materials in March 2022. Challener noted that their best-selling gemstone is Ce:LuAG, lutetium aluminum garnet (Lu3Al5O12) doped with cerium. This material was introduced to the optics industry in the late 1990s and acts as a scintillator, a fluorescent crystal that absorbs high-energy radiation such as X-rays or gamma rays and reemits them as lower-energy visible light that is much easier to detect. LuAG is closely related to YAG electronically and both have the same garnet structure, yielding a gem with similarly excellent optical and gem properties (see figure 1).
Yttrium aluminum garnet, known as YAG (Y3Al5O12), a lab-grown crystal that crystallizes in the cubic garnet structure, was one of the most popular diamond simulants from the 1960s to the mid-1970s due to its relatively good hardness (about 8.25 on the Mohs scale) and brilliance. Cartier’s replica of the 69.42 ct Taylor-Burton diamond famously used YAG. Gadolinium gallium garnet, known as GGG (Gd3Ga5O12), was the next garnet-like material to be used as a diamond simulant. GGG is slightly more brilliant and dispersive than YAG but scratches fairly easily due to its lower hardness (about 6.5 to 7.5 on the Mohs scale).
Most of these garnet-like crystals are doped with various rare earth elements such as neodymium, erbium, cerium, and ytterbium. These dopants not only increase the materials’ value in the optics industry but also yield the variously colored synthetic garnet-like crystals seen in the gem and jewelry industry today.

Figure 2. The top of a YAG boule doped with cerium and neodymium and produced by the Czochralski method, measuring approximately 36 mm in diameter and 45 mm tall. Parts of the boule that cannot be used for scientific purposes can be sold to the gem and jewelry trade for faceting. Photo by Lisa Kennedy; courtesy of Turtle’s Hoard.
These synthetic garnet-like crystals are most commonly produced by the Czochralski method, also known as the pulling method. In this melt process, the boule (a cylindrical synthetic crystal produced by a melt process) grows from a thin cylindrical seed crystal that is dipped into a melt of the desired garnet composition. The seed is rotated and then lifted very slowly at a controlled rate, allowing the melt to crystallize onto it. The material produced is extremely pure, with few inclusions or none at all. However, the material is not actually made for the gem and jewelry industry; rather, those in the industry can only purchase some of the less-perfect material and off-cuts of the boules to facet and sell (figure 2).
Challener explained, “They are lab-created, but each one has its own history beyond its use as a gem. And while there have been conflicting messages about whether some lab-grown stones, particularly lab-grown diamonds, are truly eco-friendly, the materials we work with are an inevitable byproduct of necessary crystal growth. Our modern lives rely on these materials being grown—we can’t have cell phones without lithium niobate or modern PET scanners without scintillators—so there isn’t really any additional waste associated with them.”

Figure 3. Greenish blue rough and cut ytterbium-doped YAG. The cabochon in front is 14 × 10 mm. Photo by Lisa Kennedy; courtesy of Turtle’s Hoard.
Turtle’s Hoard offered a variety of “lumogarnets,” including rough and faceted luminescent yellow and yellowish green cerium-doped GAGG (gadolinium aluminum gallium garnet, Gd3Al2Ga3O12), cerium-doped LuAG, and cerium-doped YAG (see again figure 1). In addition, they displayed rough grayish purple neodymium-doped YAG, rough and cut greenish blue ytterbium-doped YAG (figure 3), rough pinkish orange erbium-doped YAG, and rough and faceted green chromium-doped YAG, a green stone with strong red fluorescence showing simultaneous flashes of green and red based on lighting, dubbed “Christmas garnet.” Although synthetic and possessing a garnet-like structure, YAG, GGG, LuAG, and GAGG are not synthetic garnet, since they lack the chemistry of any garnets known in nature. @chapter:18 @chapter:1 @chapter:18


# Publication Year: -
# Title: Man-made Diamonds: Questions and Answers
# Abstract: A natural faceted diamond, on the left, and a man-made faceted diamond on the right. Photo by GIA

If it looks like a diamond and sparkles like a diamond, it’s a diamond – right?
These days it’s not so easy to pick out a natural diamond from among the assortment of colorless, shiny stones on display at a jewelry counter. Synthetic diamonds (also known as man-made and lab-grown) and imitation gem materials may also have a spot among the natural diamonds mined around the world. It can be confusing to know what you are looking at and what best fits what you want in a piece of jewelry.
Natural diamonds are one of nature's wonders. They can be several billions of years old, made of a single element (carbon), and are formed deep in the earth under extreme pressure and high temperature. These intense geological conditions produce the physical properties – transparency, optical appearance and hardness – valued in a cut and polished diamond.
“When it comes to a natural diamond, we are looking at something that is really a rarity and a treasure from Earth,” says Brenda Harwick, manager of on campus and lab gemology instruction for GIA. “But man-made diamonds have a place in the market as long as consumers know exactly what it is that they are buying. There are other synthetics out there – such as synthetic ruby, emerald and sapphire – so it’s not something new for the jewelry industry to have a synthetic alternative.”

A factory in Shandong, China, is producing a large number of colorless HPHT man-made diamonds for the jewelry industry. These colorless crystals are up to 3.5 carats. Jinan Zhongwu New Materials Company Ltd. Shandong, China. Photo by Jian Xin Liao/GIA
The jewelry industry uses special terms for manufactured and look-alike materials: synthetic (man-made, lab-grown or lab-created) and imitation (simulants).
Man-made diamonds are grown in a laboratory or factory. Their growth structure and atomic level defects allowing them to be readily separated from natural diamonds by a well-equipped laboratory such as GIA. Because natural diamonds and man-made diamonds have some of the same physical and other properties, even a skilled jeweler or trained gemologist cannot distinguish them by sight alone. It takes specialized equipment and trained staff in a gemological laboratory for a conclusive identification.

Cubic zirconia can be created as colorless or with color, such as these large pieces. From left: 44.49 cts, 29.86 cts and 56.60 cts. Photo by Tino Hammid
Diamond imitations only mimic the look of natural diamonds. Common simulants include colorless sapphire, colorless zircon, synthetic cubic zirconia (zirconium oxide, CZ) and synthetic moissanite (silicon carbide). Cubic zirconia and synthetic moissanite are the most important in the market. They may be natural or made in a lab, but do not share the chemical composition or physical properties of natural or man-made diamonds. Because simulants do not share those properties with diamond, they are more easily distinguished by gemologists.

Near-colorless synthetic moissanite is marketed for jewelry purposes as a diamond imitation. The faceted pieces shown here, weighing from 0.09 to 0.57 ct, illustrate the appearance of this material. Photo by Tino Hammid.
Man-made diamonds are a more common topic of discussion at the jewelry counter these days because they are being used more frequently in jewelry.
“They may be an option for some jewelry buyers as long as they are correctly identified,” says Dr. James Shigley, a long-time member of GIA’s research team who has studied and published research on man-made diamonds for decades.
It is important that you have some basic information about man-made diamonds and know what questions to ask before you shop.
What are man-made diamonds? Are they real diamonds?
Man-made diamonds have been produced for industrial purposes since the 1950s and are used in a wide variety of applications: telecommunications, laser optics, healthcare and more. In 1970, researchers at General Electric created the first, small, gem-quality synthetic diamonds that could be faceted as gems. By the mid-1980s, other manufacturers were able to grow them. Initially, they were mostly small and yellow, but the quality steadily improved, and today both colorless and colored gem-quality man-made diamonds are available to use in jewelry.

The identification of natural, man-made and treated diamonds has been the principal focus of the gem research program at GIA for more than 60 years. This is a group of natural colored diamonds (0.38 to 1.04 cts). Photos by Robert Weldon, composite by Kevin Schumacher/GIA
Robert Crowningshield, one of the pioneers of GIA’s research on diamonds and vice president of GIA for many years beginning in 1950, was able to examine some of GE’s man-made diamonds in 1970. He reported on them in a Gems & Gemology article titled “General Electric’s Cuttable Synthetic Diamonds” in 1971.
“Based on his examination of a few of these first experimentally grown synthetic diamonds, it’s amazing to me that he was able to recognize some of the distinctive visual gemological properties of synthetic diamonds – and that those are the same visual features we look at today to identify them,” Shigley says.
The material ‘diamond’ is defined as carbon atoms in a cubic structure; both natural and synthetic diamonds are made of this material.
“The vastly different conditions under which natural diamonds and synthetic diamonds form result in differences in their growth structure and in atomic level defects, so to say that they are identical is misleading,” says Tom Moses, executive vice president and chief laboratory and research officer for GIA. “If they were identical, we would not be able to tell them apart.”
But because they share essentially the same physical and optical characteristics of natural diamonds, man-made diamonds have the shine and sparkle of a natural diamond when fashioned as gems.
“One of the beautiful aspects of a polished diamond is the way light interacts with it, and it has superior hardness on the Mohs scale (which means that polished surfaces are not easily scratched or damaged),” Harwick says. “A synthetic diamond has those properties as well.”
What are they called?
Many different terms are used to describe diamonds grown artificially. Look for the use of the terms synthetic, man-made, laboratory-grown or laboratory-created. These and other terms are listed in the Federal Trade Commission (FTC) guidelines on diamonds.
“The industry uses many terms to describe them, so if you see any of these terms it’s an indication that it is synthetic,” Harwick says. “But they likely won’t use the term synthetic.”

In HPHT synthesis, a press (left) applies extremely high pressures and temperatures to a central growth chamber that contains the necessary ingredients. This results in synthetic diamond crystals with combinations of cubic and octahedral faces (center and right). Illustrations: Peter Johnston/GIA. Photo copyright: GIA & Tino Hammid
How are they made?
Man-made diamonds are produced in two ways:
High Pressure, High Temperature (HPHT): A man-made diamond is produced in a laboratory or factory by mimicking the high-pressure, high-temperature conditions that form natural diamonds in the Earth. Within a growth chamber, a source of carbon dissolves in a molten metal, and carbon atoms travel through the metal to a small man-made or natural diamond seed to produce a distinctively shaped man-made diamond crystal.
Chemical Vapor Deposition (CVD): A man-made diamond is produced in a laboratory utilizing carbon-rich gas (such as methane) in a vacuum chamber. The CVD process involves breaking down the molecules of methane gas into carbon and hydrogen atoms, which then are deposited on diamond seeds to produce a square-shaped, tabular man-made diamond crystal.
Like natural diamonds, synthetic diamonds can be subjected to treatments to change their color, or to improve their face-up appearance and clarity,” Shigley says.

In CVD synthesis, microwaves split apart the hydrocarbon molecules fed into the reactor (left). These fragments migrate down to the colder diamond seed and attach to the growing diamond surface.. The synthetic diamond grows in thin layers, and its final thickness depends on the amount of time allowed for growth. This results in flat, tabular crystals (center and right) with exteriors coated in black graphite. Illustrations: Peter Johnston/GIA
How long does it take to make a diamond?
It typically takes a few weeks to make a man-made diamond in the laboratory. This is a much shorter period than a natural diamond spends in the Earth, which can be millions or billions of years.
Where are they made?
“We believe that commercial production of synthetic diamonds for jewelry use is taking place in China, Ukraine, Russia, Japan, the United States, and perhaps elsewhere,” Shigley says.
What’s the difference?
Natural diamonds display differences in their properties from man-made diamonds due to the different growth conditions in which they form.
Crystal Shape: The temperatures for natural diamond crystal growth and diamonds made in the laboratory are similar, but diamonds grow as octahedral (eight equilateral triangular faces) crystals and man-made diamonds crystals grow with both octahedral and cubic (six equivalent square faces) crystals.

Natural and man-made growth environments result in diamond crystals with distinctive shapes. From left is a comparison of CVD, HPHT and natural diamonds. Octahedral faces are shown as yellow and cubic faces blue. Most natural diamonds grow as octahedral (right), but HPHT diamonds (center) typically show a combination of cubic and octahedral faces. Octahedral faces are completely absent in CVD diamonds (left). Directions of crystal growth are shown by arrows. Dotted lines represent the position of the seed crystal in the HPHT diamond and the edges of the crystal in the CVD diamond. Illustration by Peter Johnston.
“Cube faces grow more quickly than octahedral faces," Shigley says. “They are preserved on synthetic diamonds, but they are not preserved on natural diamonds.”
Diamonds grow differently, depending on the growth environment:

Natural diamonds grow outward on the octahedral faces
HPHT synthetic diamonds grow outward on the octahedral and cube faces
CVD synthetic diamonds grow mainly upward in one direction (a cube face)

A comparison of rough diamonds shows a 0.83 ct natural diamond crystal on the left and a 1.02 ct HPHT crystal on the right. Both crystals are from the GIA Research Collection. Photo by Orasa Weldon.
Inclusions: Natural and man-made diamonds can exhibit various inclusions (fractures, breaks, other crystals, hollow tubes) so they are not always diagnostic tools for gem identification, Shigley says.
Color: Man-made diamonds are commonly colorless, near-colorless, light to dark yellow or yellow-brown; they are less commonly blue, pink red or green. Man-made diamonds can be subjected to the same color treatments as natural diamonds, so any color is possible.
Clarity: Man-made diamonds can be from low to high clarity.
Cut: The cut of a man-made diamond is the same as a natural diamond – any cut is possible. Round brilliant is the most common shape and cutting style of colorless man-made diamonds.
Colored man-made diamonds and larger man-made diamonds are more often fashioned into a fancy shape to retain more weight from the original crystal. The shape of the crystal also influences the choice of faceting styles.
How big are they?
Man-made diamond producers are capable of growing all different sizes, from melee up to 10 carats or more, Harwick says. Typically, most commercial sizes are less than 2 carats, except for melee-size, which can be abundant.
Man-made polished diamonds fall into three size categories, according to Shigley:

Large size (approximately 5-10 carats or more): These cut stones attract media attention, but they are quite rare and are likely to have been examined and correctly identified by a gem-testing laboratory.
Commercial size (approximately 0.25 to 2.5 carats): These cut stones are more abundant, but again, they are likely to be submitted to a gemological laboratory for evaluation where they should be recognized.
Small or melee size (approximately 0.10 carats or smaller): These cut stones are the most abundant, and because of their small size, they will be more difficult to detect and are not often tested – this is the real identification challenge facing the jewelry industry

A variety of large, commercial and melee cut man-made gemstones are available in the market. These HPHT diamonds, from left, are 0.41 ct, 0.31 ct and 0.50 ct. and three melee-sized stones. Photo by Orasa Weldon/GIA
How does GIA identify and grade man-made diamonds?
Man-made gem diamonds have been extensively studied by gemological researchers for the past 30 years, and much is known today about how they are grown and how they can be identified (there is a lot of published information that has been widely distributed).
“Synthetic diamond identification means distinguishing a natural diamond that formed over a long time, and very long ago, from a synthetic diamond that formed very quickly and very recently,” Shigley says.
GIA has screened every diamond submitted to its laboratory for grading for more than a decade to determine if it is natural or potentially man-made or treated. Following the initial screening, any diamond that is potentially man-made or treated undergoes rigorous examination to confirm if it is natural or man-made, and what treatments – if any – have been applied.
GIA can definitively identify both HPHT and CVD-created man-made diamonds.

All items submitted to GIA for diamond grading services are examined using the GIA DiamondCheck™ to determine if the material is a natural diamond; a diamond that may require further testing for treatments or may be man-made; or non-diamond material. Photo by Jian Xin Liao/GIA.
What will a GIA grading report tell me?
GIA began to offer a report service for synthetic diamonds in 2006. These Synthetic Diamond Grading Reports, which GIA continues to offer, are distinct from GIA grading reports for natural diamonds in both their appearance and the information provided. They clearly identify that the diamond is man-made or laboratory-grown, and they evaluate color and clarity using descriptive ranges rather than the specific grades of the color and clarity scales.
“When these reports were introduced, there was a range of opinion in the trade about GIA grading synthetic diamonds,” Shigley says. “Since synthetic diamonds continue to be rare, and to differentiate them from what is reported on grading reports for natural diamonds, only color and clarity ranges are used.”
In addition, the man-made diamond’s girdle is laser inscribed with its report number and a statement that the stone is laboratory- grown. GIA does this for every man-made diamond identified in its labs.
“The inscription on the girdle can be key to its identification,” Harwick says.
The reports also use the other Federal Trade Commission (FTC) approved terms – man-made and lab-grown – for synthetic diamonds.

There are legal and ethical requirements that a jeweler must disclose a gem’s identity at the time of sale. This helps ensure consumer confidence in what they are purchasing.
Considering a man-made diamond … what to expect?
Make sure you go to a reputable jewelry store with professionally educated gemologist to purchase any diamond jewelry. They can act as your guide as you look at natural and man-made diamonds.
“A sales associate should articulate or represent and disclose accurately what they are presenting to you. If they are calling it ‘diamond,’ you are assuming it is natural,” Harwick says. “[If it’s not natural] they need to be forthcoming in their description and are required by the FTC to call it laboratory-created, synthetic, laboratory-grown or manufacturer-created.”
Ask the sales associate if it is a natural or man-made diamond and how they know this information.
“Synthetic diamonds may be difficult to recognize by a jeweler or a trained gemologist, but they do not present an identification challenge for GIA,” Shigley says. “There are a variety of instruments being offered to jewelers so they can check for synthetic diamonds, but GIA does not use them so it is not appropriate for us to comment on their operation or accuracy.”
Ask for a diamond grading report from a recognized gemological laboratory – these clearly disclose the identity of the diamond. GIA reports for natural and synthetic diamonds look very different.
“When you’re making an investment in something as precious as this, you should ask for a grading report,” Harwick says.
How much do man-made diamonds cost in relation to their natural counterparts?
Russell Shor, senior industry analyst for GIA, says that producing man-made diamonds, either by HPHT or CVD methods, is quite costly.
“The fact they can be sold for a third or less than a natural diamond suggests they are often priced relative to natural diamonds, rather than priced in a way that reflects a true market for synthetics,” Shor says. Like most technologies, however, he notes that innovations may bring down production costs and, accordingly, the demand for them will increase.

These colorless CVD-grown synthetic diamonds can appear the same as natural diamonds to the unaided eye, making proper identification by a gemological laboratory important. Photo by Jian Xin (Jae) Liao/GIA
What is the future potential of man-made diamonds?
No one knows for sure if man-made diamonds will become a popular choice for shoppers long-term. There are personal choice issues for each buyer to consider before they purchase one.
“It is up to the preference of the consumer whether they purchase a natural or synthetic diamond, however, proper disclosure about the nature of their stone is paramount,” says Wuyi Wang, director of GIA’s research and development. “As long as the origin of the diamonds is fully disclosed, consumers and the market will determine the future for synthetic diamonds.” @chapter:41 @chapter:1 @chapter:41


# Publication Year: 1989
# Title: The Characteristics and Identification of Filled Diamonds
# Abstract: The filling of surface-reaching cleavages, fractures, and other separations in diamonds has generated a great deal of concern during the last two years. This article reports on the study of six diamonds both before and after a filling treatment and the examination of 12 additional filled stones. Microscopy provides the best means of identifying that a stone has been filled. Chemical and other analyses indicate that the filling material is a type of glass. The filling will not withstand all standard jewelry manufacturing and repair procedures. @chapter:41 @chapter:1 @chapter:41


# Publication Year: -
# Title: Fall 2023 G&G Available Now
# Abstract: The Fall issue of Gems & Gemology has a wide range of colored stone topics in store, from the cause of color in yellow sapphire to the characterization of Oregon sunstone, Ukrainian beryl, and British Columbian iolite. In addition to the four feature articles and our quarterly sections, we see the return of Diamond Reflections and the 2023 G&G Challenge results.
YELLOW SAPPHIRE: NATURAL, HEAT-TREATED, BERYLLIUM-DIFFUSED, AND SYNTHETIC
Dr. John Emmett and fellow researchers share their in-depth study of the various chromophores responsible for color in natural, heat-treated, beryllium-diffused, and synthetic yellow sapphire. Their results reveal that Fe3+, a trapped hole associated with iron (h•-Fe3+), or a combination of the two are involved in the coloration of natural and treated yellow sapphire, while color in synthetic yellow sapphire is attributed to the Ni3+ chromophore or a combination of Ni3+ and Cr3+.
SPECIAL COLORS AND OPTICAL EFFECTS OF OREGON SUNSTONE: ABSORPTION, SCATTERING, PLEOCHROISM, AND COLOR ZONING
Dr. Shiyun Jin and colleagues investigate the special colors and optical effects caused by metallic copper inclusions in Oregon sunstone using samples from various mines. Their study covers the absorption and scattering of light as well as pleochroism and color zoning in this increasingly popular gemstone from the United States.
ETCH PITS IN HELIODOR AND GREEN BERYL FROM THE VOLYN PEGMATITES, NORTHWEST UKRAINE: A DIAGNOSTIC FEATURE
The Volyn pegmatite field in Ukraine is known for the production of green beryl and the yellow beryl variety heliodor. Led by Dr. Gerhard Franz, researchers present their study examining the dissolution features of Ukrainian heliodor and green beryl and offer criteria to distinguish them from samples found in other localities.
IOLITE FROM THE THOR-ODIN DOME, BRITISH COLUMBIA, CANADA: GEOLOGY, CHEMICAL COMPOSITION, INCLUSIONS, AND CAUSE OF CHATOYANCY
Dr. Philippe Belley reports on gem-quality cordierite from two recently discovered occurrences in British Columbia—Blue Arrow and Blue Bear. The paper details the geological setting and gemological properties of this violet-blue iolite and notes the potential for future discoveries in the area.
LAB NOTES
GIA’s global laboratory staff share their latest findings in the Lab Notes section, including two traditional Indian pearl submissions to the Mumbai lab—a Bombay pearl bunch and two pearl nose rings—and a ruby filled with zinc glass examined in the Carlsbad lab.
MICRO-WORLD
The Micro-World section continues to highlight fascinating gem inclusions with an intricate moiré pattern in purple spinel, blade-like magnetite inclusions in peridot, brown matrix in an Armenian turquoise sphere mimicking planet Earth, and more.
DIAMOND REFLECTIONS
Diamond Reflections returns to explore diamonds formed within eclogitic mantle host rocks and what they reveal about Earth’s dynamic processes.
GEM NEWS INTERNATIONAL
Finally, GNI contributors report on new occurrences of basalt-related gems in southeast Vietnam, an assessment of responsible pearl farming in Australia, the opening of the Gübelin Gem Museum in Switzerland, and more. @chapter:13 @chapter:0 @chapter:13


# Publication Year: 2014
# Title: Books: In Praise of Hands: The Art of Fine Jewelry at Van Cleef & Arpels
# Abstract: By Franco Cologni, 199 pp., hardcover, illus., publ. by Marsilio Editori, S.p.a. Venice, 2012, $90.00.

              Van Cleef & Arpels, born from the matrimonial alliance of two prominent Dutch jewelers’ families in 1895, opened their boutique in Paris’s Place Vendôme in 1906 and quickly gained international acclaim. Over the years, the maison created iconic jewelry pieces, such as invisibly set floral brooches, fashionable minaudières and cigarette cases, Ludo Hexagone bracelets, and zipper necklaces. One of the forces behind the firm’s meteoric rise was its excellence in design and craftsmanship. As part of its public relations and branding strategy, Van Cleef & Arpels emphasizes quality craftsmanship and respect for traditional techniques. In Praise of Hands embodies this branding effort. This luxurious book, titled in honor of art historian Henri Focillon’s 1943 philosophical essay on how hands shape art, celebrates Van Cleef & Arpels’s Mains d’Or, or most skilled craftspeople.

The book’s first eleven chapters correspond to various specialized crafts: “The Designer,” “The Mock-Up Maker,” “The Jeweler,” “The Setter,” “Mystery Setting,” “The Stone-Cutter,” “The Diamond-Cutter,” “The Polisher,” “The Smelter,” “The Sculptor-Engraver,” and “The Boîtier.” Each explains, in great detail, a given stage of the design and manufacturing process. Some chapters are of particular interest for jewelers, such as “The Designer,” “The Smelter” and “The Polisher.” These craftsmen are instrumental in creating and giving shape to all jewelry pieces, so it is important to have them featured. For gemologists, “The Stone-Cutter” and “The Sculptor-Engraver” are extremely informative, providing great detail on both processes. The most stimulating and revealing chapters to jewelry enthusiasts are “The Mock-Up Maker,” “Mystery Setting,” and “The Boîtier.” These allow the reader to uncover some of Van Cleef & Arpels’ manufacturing secrets and better fathom its high level of craftsmanship. For instance, the systematic use of mock-ups, made of alloy and rhinestones, demonstrates the utmost attention to detail and practicality. This rendering technique is poles apart from today’s abstract 3D CAD/CAM projections. It allows design and production teams to spot potential technical problems and even provides for price estimates of jewelry pieces at an early stage.

One of the book’s strong points is its display of artful color jewelry renderings. Given the Place Vendôme’s world of secrecy, it is worth noting that some of the sketches feature serial numbers, names of patrons, and details on gemstone costs and corresponding vendors. This type of information is useful to anyone involved in jewelry pricing.

The book is selectively illustrated with three categories of photos. The first type consists of original color sketches with corresponding magnified shots of antique pieces, many of them from the jewelry house’s archival collection. The second type consists of black-and-white photos, using the chiaroscuro technique, of the Mains d’Or craftspeople at work. The third type, appearing at the end of each chapter, features a general shot of a recent piece alongside a detailed photo (showing individual gemstones in some cases). The opening and ending chapter photos are well suited to the chapters’ topics, proving that the craftsmanship inherent in past masterpieces is still alive.

On the down side, there is a relative disconnect between the photos of artisans’ hands and the contemporary jewelry pieces shown at the ends of sections. There would have been greater impact if the book had shown the same piece twice, once between the hands of a jeweler during its making and once completed. The photos of jewelers’ hands, though certainly a strong homage to their skills and dedication, are a superficial representation. At best, these pictures convey the contrast between rugged hands and delicate jewelry components in various stage of completion, as well as the artisans’; strength and dexterity. Yet focusing on their hands is too restrictive, and does not convey the physicality involved in jewelry making. The process is not limited to the hands; rather, it is a constant connection between hands, eyes, and brain, which is difficult to capture in photos. The concluding chapter, “The Crafts,” presents photos of all the craftsmen’s hands. This allows the reader to envision the actual handling of a piece through the different steps.

The text is extremely informative and detailed on all the phases of jewelry manufacturing. It does not shy away from technical descriptions—including an impressive list of tool names—while remaining inviting and accessible. It gives way, however, to the repetition of clichés, such as the poetic vision of the maison’s single-minded pursuit of perfection, beauty, and total control over its whole manufacturing process.

Despite these few shortcomings, the book is a must-have for jewelry students, bench jewelers, and gem experts who wish to become more familiar with this exclusive brand. Cologni describes a level of craftsmanship and organization that is almost extinct in the industry today. Van Cleef & Arpels’s variety of inspirations, design creativity, and manufacturing quality are among the very highest, and this opus is a beautiful tribute. @chapter:20 @chapter:2 @chapter:20


# Publication Year: -
# Title: Visit to the China Diamond Exchange Center
# Abstract: Shanghai, one of the world’s financial capitals, is home to the China Diamond Exchange Center. Photo courtesy of China Diamond Exchange Center.

                      In July 2013, a GIA team visited the China Diamond Exchange Center in Shanghai during an extensive trip undertaken to document China’s gem and jewelry industry. The trip was arranged by Dr. Tao Hsu, technical editor for Gems & Gemology, and the Exchange was an important part of the itinerary.

	The Diamond Exchange in Shanghai is home to dealers, government agencies, a lab,
	and shipping services. It is the central location for all of China's diamond imports and
	exports. Photo courtesy of China Diamond Exchange Center.
The China Diamond Exchange Center is home to the Shanghai Diamond Exchange (also known as the Diamond Exchange). Before it was established in October 2000, taxation—including import tariff, value added tax (VAT), and sales tax on imported diamond—was around 35 to 40 percent. Diamond taxation policy is now very favorable in China, with a VAT of only 4 percent. (In reality, all goods imported into China are charged 17 percent VAT, but 13 percent is refunded for diamonds, leaving the net VAT charge on diamond at 4 percent.) This lowered taxation came about due to input from the Diamond Exchange, and it was instrumental in greatly reducing the quantity of diamonds smuggled into the country to avoid the higher taxes.

	The Shanghai Diamond Exchange was established in October 2000. Photo courtesy of China Diamond Exchange Center. .

	The Exchange’s Influence
The Chinese diamond industry benefited greatly from the formation of the Diamond Exchange. Before it was established, official annual diamond import value was about US$1 million. By 2011, import value had reached over US$5 billion, of which $2 billion was imported solely into mainland China. While imports dropped by 10 percent in 2012 due to worldwide economic conditions, indications for 2013 are that the import figure will be higher.

The Diamond Exchange joined the World Federation of Diamond Bourses in 2004, and hosted the 33rd World Diamond Conference in Shanghai in 2008.

	The 33rd World Diamond Conference was held at the Diamond Exchange in 2008. Photo courtesy of China Diamond Exchange Center.

	The Mission of the Exchange
The Diamond Exchange is China's only legal location for diamond import and export. Set up by the central government, its mission is to make trade more convenient by simplifying diamond import and export procedures.

According to Chinese law, all imported diamonds must go through the Exchange and several procedures must be followed. One of those is that diamonds imported into China must be declared and sealed in customs, or they are considered illegally smuggled. The diamonds are unsealed, inspected, and assessed by an expert at the Exchange before taxation is imposed.

	All diamonds entering China, both rough and cut, must come through the China
	Diamond Exchange. Photo courtesy of China Diamond Exchange Center.

	Kimberley Process Certificates
Kimberley Process certificates must accompany rough diamonds. Their mandatory inspection is strictly carried out in China. A special department in the Diamond Exchange  is set up for inspecting and registering Kimberley Process certificates. Once the certificates pass inspection, the rough can be sold in the domestic market. China was elected as the Deputy Chairman Country of the Kimberley Process in 2013. In 2014 China became the Chairman Country and one officer of the National Bureau of Quality Inspection will took the Chairman position.

	Kimberley Process certificates for rough diamond are inspected and registered in a specialized department of the Diamond Exchange. Photo courtesy of China Diamond Exchange Center.

	Open Platform
The China Diamond Exchange Center is a totally open platform that welcomes diamond dealers from all over the world. It has more than 350 members, among which 67 percent are overseas members from Israel, Belgium, Great Britain, France, the United States, Japan, Africa, and other countries. There are 114 member diamond companies from mainland China, 62 from Hong Kong, 50 from India, 32 from Israel, 23 from Belgium, and the rest from other countries.

	The China Diamond Exchange is one of the world’s leading diamond exchanges and attracts industry leaders from all over. Photo courtesy of China Diamond Exchange Center.

	Membership Requirements
A diamond company that wants to be a member of the China Diamond Exchange has to meet certain requirements. The first requirement is that the company must have been engaged in the industry for at least three years and must be familiar with its operation. Secondly, the company must be introduced by two registered members of the China Diamond Exchange. A new member has to go through a one-year probationary period.

The third is a financial requirement: a mandatory US$20,000 one-time admission fee. The fee is refundable if a member wants to withdraw from the Exchange as a result of unsuccessful business endeavors or some other reason.

Another important condition is that a diamond company operating in China must be approved by the Diamond Administration of China (DAC) and registered according to Chinese law. After approval and licensing by the DAC, a company is allowed to engage in import and export business and take part in customs, tax administration, and Kimberley Process procedures.

	Diamond-trading information from the China Diamond Exchange attracts many dealers who want to do business in this fast-growing market. Photo courtesy of China Diamond Exchange Center.

	Main Functions of the DAC
The DAC and other government organizations jointly control everyday diamond imports and exports across the country as well as trade within the China Diamond Exchange.

The main functions of the DAC are administration and statistical analysis of national diamond imports and exports under normal trade conditions; examination and verification of transactions under rules of the Diamond Exchange, as well as supervision of the Exchange’s operations; and  coordination with other government officials inside the Exchange regarding issue relating to the diamond trade. The DAC also conducts examination and approval of the establishment of foreign-invested diamond companies, and daily regulation of their operations. It participates in the formulation of regulations and policies concerning diamond import and export and other diamond transactions, and provides  services to the Exchange and to domestic and foreign diamond companies.

	Building and Departments
The tower that houses the China Diamond Exchange Center is an impressive structure in Shanghai that covers an area of 49,000 square meters. The building is designed to be a one-stop shop for the diamond trade and boasts the latest in security, communications, and technology. The DAC is located in the tower, along with other diamond-related government organizations.

	The Diamond Exchange is a one-stop shop for all diamond trading needs, from taxation requirements to shipping. Photo courtesy of China Diamond Exchange Center.
Supporting businesses include banking, a grading lab, shipping companies, training organizations, diamond associations, and security escorts.

Customs
Customs is in charge of handling the declaration of diamond import and export, the checking of diamonds passing through the Exchange, the collection of diamond import tax, supervision of the trade and storage of diamonds inside the Exchange, and checking of diamonds going out of the Exchange for processing.

Inspection and Quarantine Administration
The Inspection and Quarantine Administration is responsible for Kimberley Certificate verification and issuance. It also checks rough import and export under normal trade in China and under subcontracted trade in Shanghai.

The Taxation Office
The Taxation Office is in charge of the administration of taxes for Exchange members’ domestic trade. The Pudong branch of the taxation office is in charge of handling VAT for member enterprises.

The Industrial and Commercial Office and Foreign Exchange Office
The Industrial and Commercial Office is in charge of diamond-related industrial and commercial administration, while the Foreign Exchange Office is in charge of diamond-related foreign exchange administration.

	Government departments within the Diamond Exchange handle all the legal aspects of dealing in diamonds in China. Photo courtesy of China Diamond Exchange Center.

	China Diamond Industry Development
Diamond jewelry entered the mainstream Chinese market in the 1980s. Along with rapid economic and social development, the continual improvement of people’s living standards, and the fast rise of consumerism, diamond jewelry sales have been increasing at a rate of 15 to 20 percent a year. China is now the world’s second largest consumer market for diamonds, overtaking Japan.

China’s diamond-polishing industry also started to grow significantly in the early 1980s, and growth became more rapid in the 1990s. Currently, China is the second largest diamond-polishing country, after India. China polishes over six million carats of diamonds annually and employs over 50,000 polishers in more than 80 medium and large factories. Most of the factories are located in Guangdong, Shandong, and Shanghai. China has developed a niche for high-quality precision cutting and marketed their product as China Cut.

	China has a thriving diamond-polishing industry. Photo courtesy of China Diamond Exchange Center.
Most of the diamond polishing in China is subcontracted work for foreign clients, who hire domestic firms to polish their diamonds. There are also numerous jewelry manufacturing firms producing diamond jewelry for export.

All of this phenomenal growth is due in part to the policies and organization of the China Diamond Exchange Center in Shanghai. @chapter:37 @chapter:3 @chapter:37


# Publication Year: 2024
# Title: “Cyber” Butterfly
# Abstract: The rectilinear zigzag-patterned fingerprint and the negative crystal in the center are reminiscent of a beautiful “cyber” butterfly trapped in this 2.56 ct purple sapphire. Photomicrograph by Yuxiao Li; field of view 2.60 mm.
The author recently examined a 2.56 ct purple octagonal step-cut sapphire. This sapphire contained a negative crystal with a sharp rectilinear zigzag-patterned fingerprint, providing strong evidence that no heat treatment took place. Under fiber-optic illumination, the fingerprint displayed vibrant colors due to thin-film interference. The combination of the fingerprint and negative crystal created an image reminiscent of a digital butterfly (see above). Both the negative crystal and the unique fingerprint were caused by the natural healing of a surface-reaching fracture in the sapphire host. The healed areas parallel to the c-axis displayed rectangular outlines, resulting in the “cyber” appearance of the wings. @chapter:43 @chapter:1 @chapter:43


# Publication Year: -
# Title: Tanzanite Quality Factors
# Abstract: Tanzanite is one of the most popular colored gemstones in the world.- Courtesy Tanzanite Foundation ™

Tanzanite is a versatile gemstone that comes in a variety of sizes and cutting styles. Although it was only discovered in the late 1960s, it has quickly established itself as one of the premier gemstones in the world.

Color
Tanzanite is a pleochroic gem, which means it can show different colors when viewed in different crystal directions. This makes cutting a crucial element in determining the color the consumer sees when the stone is cut and set in jewelry.

Tanzanite’s color can be a very bright, intense blue.
In exceptional tanzanites, the color is an intense violetish blue with red flashes of pleochroic color coming from within the stone. Due to the gem’s strong pleochroism, fashioned examples typically show a mix of both blue and violet colors in a wide range of tones. As with most colored gemstones, paler colors are more available and affordable than saturated ones.

In this crystal direction, this tanzanite's violet-to-purple pleochroic color is evident. - Jeff Scovil
Untreated, tanzanite is typically brownish. Most blue tanzanites for sale today owe their color to heat treatment, which is what reveals the gem’s attractive pleochroic blues and violets. The blue crystals originally discovered by Masai tribesmen were an exception because they’d probably been exposed to a natural heat source within the earth at some point.

As trade professionals assume the majority of the tanzanite on the market has been heated in some way, there’s little effect on pricing. In many cases, it’s challenging for gemological laboratories to determine whether a tanzanite has been heated.

Clarity
Much of the tanzanite sold for jewelry has inclusions that can be seen only under magnification, so any eye-visible inclusions cause a drop in value.  Also, any inclusions that might pose durability problems, such as fractures, lower tanzanite value greatly.

Most tanzanites cut as faceted gemstones for use in jewelry contain no inclusions that are visible to the eye. - Courtesy Tanzanite Foundation ™

Rarely, tanzanite can contain inclusions that cause a cat’s-eye effect.
Cut
Cutting plays an important role in tanzanite’s color display. Because of its pleochroism—the ability to show different colors when viewed in different crystal directions—cutting direction determines the gem’s overall face-up color.

This award-winning jewelry piece features two triangular tanzanites set back to back. The stones were cut with the proper orientation and proportions to allow maximum enjoyment of their deep violet blue color. - Courtesy Tanzanite Foundation ™
Cutters consider financial realities when they decide how to cut tanzanite. As with other gems, weight lost is profit lost. Cutting a tanzanite to emphasize the violet-to-purple color usually wastes less rough than cutting it to get a violetish blue color. That's part of the reason face-up violet-purple tanzanites are more plentiful than specimens with a stronger blue color component.

Tanzanite is sometimes cut in designer fantasy styles. - Courtesy Mark Schneider
But this decision must be balanced against the higher per-carat price that the finer violetish blue color might bring. The cutter essentially makes a choice between a smaller top-color gem and a larger violet-purple one.

Carat Weight
Tanzanite is available in a wide variety of sizes, shapes, and faceting designs. The finest and deepest colors are usually seen in sizes over 5 carats. Smaller stones are often less intense in color.

Tanzanite can be found in large sizes for jewelry use. This is a square-cut 37.07-carat stone - Courtesy Robert Kane, Fine Gems International

This suite of tanzanite jewelry has a total weight of 500 carats. - Courtesy Intercolor @chapter:0 @chapter:0 @chapter:0


# Publication Year: 1991
# Title: Summer 1991 G&G Lab Notes
# Abstract: Amber Damaged in Cleaning
Large Electron-Treated Diamond
Electron Treated Diamond in Period Jewelry
Fracture Filled Diamond
Green Surface-Colored Rough Diamond Fashioned to a Fancy Light Yellow
Green Diamond with Radiation Stains in Etch Channels
Pearl Cultured "Demi-Pearl"
Freshwater "Rosebud" Pearls
Rare Assembled Cultured Blister Pearls
An Early (?) Flux-Grown Synthetic Ruby
Spinel with Unusual Green Fluorescence
Cobalt-Colored Synthetic Spinel with Unusual Inclusions
Dark Blue Topaz Damaged by Treatment
Radioactive Zircon

To view the full section, download the PDF above. @chapter:43 @chapter:1 @chapter:43


# Publication Year: 2019
# Title: Unique Orange Sapphire with Golden Sheen Effect Reportedly from Kenya
# Abstract: Figure 1. This 4.34 ct transparent oval-cut orange sapphire displayed an attractive golden sheen effect. Photo by Tasnara Sripoonjan.

Golden sheen sapphires from Kenya have been reported in this journal and elsewhere (e.g., T.N. Bui et al., “From exsolution to ‘gold sheen’: A new variety of corundum,” Journal of Gemmology, Vol. 34, No. 8, 2015, pp. 678–691; N. Narudeesombat et al., “Golden sheen and non-sheen sapphires from Kenya,” The Gem and Jewelry Institute of Thailand, July-August 2016, pp. 282–288). Those sapphires, however, were the cabochon-quality blue-green-yellow stones that exhibited a shimmering golden effect caused by the light reflection from hematite platelets and needle-like inclusions. No faceted transparent stones have been mentioned in the previous literature. Recently the Gem and Jewelry Institute of Thailand’s Gem Testing Laboratory in Bangkok encountered a faceted orange sapphire with an attractive golden sheen effect that was reportedly from Kenya.
The sample was a transparent, 4.34 ct faceted mixed-cut stone of orange hue with attractive golden sheen effect almost throughout the crown facets (figure 1). Standard gemological testing revealed a refractive index (RI) of 1.765 to 1.775, a birefringence of 0.01 with a uniaxial negative optic sign, and a hydrostatic specific gravity (SG) of 3.98. The stone exhibited brownish orange and greenish yellow pleochroism and was inert to both long- and short-wave UV radiation. Microscopic observation revealed abundant metallic hematite platelets and rutile needles (figure 2, left), confirmed by Raman spectroscopy, that were situated along the basal pinacoid face. A cluster of zircon crystals, as suggested by its crystal morphology, could also be found in the specimen (figure 2, right).

Figure 2. Internal features of the orange golden sheen sapphire: abundant metallic hematite platelets and rutile needles (left) and a cluster of zircon crystals (right). Photomicrographs by Saengthip Saengbuangamlam; field of view 3.00 mm.
In previous studies, the golden sheen sapphires from Kenya were translucent to opaque, with yellow and blue bodycolor (Bui et al., 2015; Narudeesombat et al., 2016). They contained abundant internal features, such as exsolved intergrowth Fe-Ti oxide phases of hematite platelets and short ilmenite needles that gave the sheen effect, as well as inclusions of goethite, boehmite, and diaspore needles. They also had large surface-reaching cracks. The stone in this investigation is orange, transparent, and without surface-reaching cracks, though it also possesses a significant number of hematite platelets that are in part responsible for its golden sheen effect.

Figure 3. UV-Vis spectra of the orange golden sheen sapphire showing Fe3+ - and Cr3+-related absorption peaks and bands.
The polarized ultraviolet-visible (UV-Vis) spectra of the specimen displayed predominantly Fe3+-related absorption bands at 378, 388, and 450 nm that are responsible for its yellow hue (e.g., J. Ferguson and P.E. Fielding, “The origins of the colours of natural yellow, blue and green sapphires,” Australian Journal of Chemistry, Vol. 25, No. 7, 1972, pp. 1371–1385), whereas the absorption band at around 557 nm (also at ~410 nm) is caused by a Cr3+ transition contributing to the reddish hue (figure 3). As such, the stone coloration appears orange. R-line luminescence of Cr3+ near 693 nm also appears in the spectra. When compared to the more common non-sheen counterparts, the UV-Vis spectra yield only Fe3+- and Fe-Ti-related absorptions (Narudeesombat et al., 2016).

The energy-dispersive X-ray fluorescence (EDXRF) results of the orange sapphire showed very high content of Fe2O3 (1.94 wt.%) with moderate content of Cr2O3 (0.05 wt.%) and TiO2 (0.04 wt.%). Ga2O3 and V2O5 were equal at about 0.01 wt.%. This result (particularly the iron content) is somewhat similar to those of the common golden sheen and non-sheen stones from Kenya in the previous work (table 1), which also suggests a similar magmatic source. Nonetheless, the Cr2O3 content in this orange sapphire is particularly distinctive, since such an oxide is almost undetectable in most golden sheen sapphires.
While Kenya is known to supply large amounts of golden sheen sapphires, some rare orange sapphires with sheen effect such as this one are also being supplied to the market. Sheen effect makes the stone distinctive compared to common orange sapphire from other sources, for example, from Songea in Tanzania (cf., originating from a metamorphic source and having somewhat lower iron content). However, the owner informed us that this specimen might eventually be subjected to heat treatment at a relatively low temperature to remove some silk-like inclusions and make it more transparent. Nevertheless, careful examination yielded no indication that this stone was heated. Its unique characteristics—heavily included hematite platelets and rutile needles that give rise to the golden sheen effect plus its high iron content—suggest a Kenyan origin. @chapter:10 @chapter:0 @chapter:10