Publication Year: 2016 Title: Blue Sapphires From a New Deposit Near Andranondambo, Madagascar Abstract: Figure 1. These three rough unheated sapphire crystals, weighing (from left) 9.98, 14.56 and 7.7 ct, are reportedly from Madagascar’s newest rush area. Beside them are heat-treated faceted sapphires believed to be from the old deposits around Andranondambo. The pear-shaped faceted stone weighs about 4.17 ct. Photo by Vincent Pardieu/GIA.

In January 2016, author VP was informed by Nirina Rakotosaona (Societe Miniere du Cap, Madagascar) and Jack Mampihao of a sapphire rush in the south of the island near Andranondambo. The blue sapphires (figure 1) are reportedly from a primary deposit and similar to those produced near Andranondambo, the region that put Madagascar on the map as a world-class sapphire source two decades ago (D. Schwarz et al., “Sapphires from the Andranondambo region, Madagascar,” Summer 1996 G&G, pp. 80–99). Details emerged as miners returned from the rush in February. According to these firsthand accounts, the new mines are located near Vohitany, north of Tiramena (figure 2). They are only accessible by foot, and it takes about a day of walking from Tiramena to reach the area.

Figure 2. According to miners, the new deposit is located near Vohitany, north of Tiramena.
This remote area is only accessible by foot.
The author’s contacts in Madagascar did not consider it safe to travel to that area, which is known to be a haven for bandits, called malaches or dahalo. In early February, the author learned from Karim Guerchouche (Premacut, Bangkok) that a 1 kg parcel of the new material had arrived in Thailand. The owner, Isaac Stern, wanted to perform some heat treatment experiments with Premacut. This offered us a chance to conduct a preliminary study of the material before visiting and collecting samples at the site.

Most of Mr. Stern’s parcel consisted of rough weighing between 1 and 4 ct. The largest stone was an etched crystal weighing nearly 15 ct (again, see figure 1). The parcel was composed of attractive, well-formed crystals still associated with kaolin. Out of more than 300 stones studied, only one showed some indication of weathering. This suggests that the material is from a primary deposit. The stones were euhedral transparent crystals with strong blue color zoning. Overall, the material was very similar to the specimens the author collected in Andranondambo and Tiramena during visits in 2005, 2008, and 2010.

Sixty-three stones from the original parcel (mainly clean and milky specimens) were selected for a heat treatment experiment. Fifteen other stones, most of which hosted inclusions, were studied at GIA’s Bangkok lab (figure 3). The study confirmed their similarity to GIA reference samples from Andranondambo; details will be published in a News from Research entry on the GIA website.

Figure 3. A detailed view of the 15 unheated samples selected for a preliminary study. The stones were placed on a light box and are seen here using bright diffused light. Under such conditions, the strong color zoning is obvious. Photo by Sasithorn Engniwat/GIA.
The new stones showed a medium to high iron content (between 300 and 1100 ppma), consistent with the classic Andranondambo material. Strong blue color zoning and an abundance of negative crystals dominated the inclusion scene (figure 4). Many stones contained bands of minute particles, thin needles, and growth tubes. Calcite mineral inclusions were common; we also identified mica and apatite crystals.

Figure 4. A blue sapphire from Madagascar’s newest deposit hosts this group of negative crystals. Some crystals host white hairlike diaspore needles, identified using Raman spectroscopy. Photo by Victoria Raynaud/GIA; field of view 1.2 mm.
The heat treatment experiment was successful. The light-colored, slightly milky material turned into fine transparent, deep blue stones after heat treatment under reducing conditions for seven hours at approximately 1600°C. Most of the included stones broke during the experiment, probably due to the presence of negative crystals.

This exciting discovery suggests that the Andranondambo sapphire deposit is much larger than originally expected. The main challenges are the security issues and the nature of the deposit itself, as the rocks hosting the sapphires are very difficult to work. @chapter:37


Publication Year: 2017 Title: Flux-Grown Pink Synthetic Sapphire with Unusual Crystal Inclusions Abstract: Figure 1. This pink stone proved to be a flux-grown synthetic sapphire with unusual crystal inclusions. Photo by Robison McMurtry.

The Carlsbad laboratory recently received a saturated pink cushion mixed cut, mounted in a ring, that measured 14.02 × 10.35 × 6.24 mm (figure 1). Standard gemological testing yielded a refractive index of 1.760–1.768 and a weak ruby spectrum using a handheld spectroscope, properties consistent with pink sapphire. The stone displayed a strong orange fluorescence under long-wave UV and an odd chalky orangy yellow fluorescence under short-wave UV. While orange fluorescence is not unusual in pink sapphires, the intensity and the chalky yellow reaction were suspicious.

Microscopic examination revealed a single hexagonal, dark reflective platelet (figure 2); numerous transparent, colorless tabular to rounded doubly refractive crystals (figure 3) that showed interference colors under crossed polarizers; and a small fingerprint composed of elongated tubules. Observation in immersion showed some weak, straight orange and pink zoning. This inclusion scene could easily be mistaken for natural as the transparent crystals bore a certain resemblance to zircon, a common inclusion in natural sapphires and particularly pink sapphires from Madagascar. The dark reflective platelet, which was presumably platinum, and odd fluorescence prompted further investigation.

Figure 2. This dark reflective platinum platelet observed in the pink synthetic sapphire is a common inclusion in flux-grown synthetic corundum. Photo by Nathan Renfro; field of view 1.82 mm.

Figure 3. The abundance of transparent crystals and crystal clusters could easily be mistaken for a natural inclusion scene in a pink sapphire from Madagascar. Photo by Nathan Renfro; field of view 1.79 mm.
The synthetic nature of the sapphire was confirmed using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). High amounts of Pt were detected, which would support a flux synthetic growth process. Small amounts of Fe and Be were present; Ga, Ti, and V were not detected. This chemical profile also supports synthetic sapphire.

Transparent crystals of possible chrysoberyl (BeAl2O4) have been previously cited in flux-grown synthetic corundum (R.E. Kane, “The gemological properties of Chatham flux-grown synthetic orange sapphire and synthetic blue sapphire,” Fall 1982 G&G, pp. 140–153). In that case, Chatham stated that heavy concentrations of beryllium were added to the original aluminum oxide formula, which would explain the presence of those crystals. In our pink sapphire, none of the crystals reached the surface, so we were unable to identify them with Raman spectroscopy. Small amounts of beryllium were detected, so chrysoberyl could be a possibility in this case as well.

The presence of these natural-looking crystals combined with the general lack of other inclusions for a stone of this size, particularly diagnostic flux fingerprints, could make correct identification very difficult for gemologists without access to advanced instrumentation. This is one case where advanced testing in a well-equipped gemological laboratory was necessary to make a conclusive identification. @chapter:12


Publication Year: - Title: Trade Hopes for a Bright 2019 Vegas Show Abstract: Business at the May 9-12 GemGenève show was soft reflecting a slowdown in the luxury market. Photo by Russell Shor/GIA

All eyes are on the upcoming jewelry sales events in the U.S. – the Luxury and JCK shows in Las Vegas – as business slows in other parts of the world.
Diamond dealers and jewelry manufacturers are expecting decent sales, based largely on demand this spring from diamond and gemstone wholesalers. U.S. retailers have been buying diamonds up to 1.5 ct and colored gems in the under-$1,000 range, and dealers expect this to continue in Vegas.
A strong turnout will help the middle of the diamond pipeline, which has been beleaguered by high inventories (causing prices to soften in most size and quality categories, especially at the lower end) and ever-tightening credit. Some dealers expect a larger-than-usual pre-show deal dash from those buying bargains from other exhibitors who need cash to pay bankers before the show opens. Colored stone dealers said demand has been improving for popularly priced stones that offer a distinctive look without an extremely high price tag.
Buyers attending the Las Vegas shows will likely see additional suppliers of laboratory-grown diamonds. The number of producers has expanded and demand has reportedly grown – with a number of mainstream jewelers offering them – and prices have reportedly dropped significantly since last year’s show.
Dealers base their optimism on the strong U.S. economy, but there are significant issues affecting the retail business: lack of wage growth among large numbers of consumers; competition from online sales; trends away from luxury items among younger buyers; and the decline of shopping centers, which have depressed sales to the point where some major retailers are in financial difficulty. Of the publicly traded retail jewelers, Tiffany & Co. reported that same-store sales were up 5%, while Signet Corp. (Kay, Zales, Jared, Piercing Pagoda) posted a sales decline of 2% in their most recent quarters.
China, however, continues to slow and the country’s government is trying to reduce the flow of funds out of the country as it grapples with the U.S. trade war. Dealers say the move has deterred many Chinese buyers from acquiring high-ticket luxury goods, including large diamonds and major gemstones. It is also hampering Chinese wholesalers who buy significant numbers of diamonds, gems and jewelry pieces from overseas suppliers.
In addition, Hong Kong banks are adopting stricter credit and money transfer regulations, according to traders based there. They say that these rules, coupled with the general slowdown, have caused a number of large gem companies to downsize and have forced some smaller ones out of business.
Exhibitors at the May GemGenève show, which was geared mainly toward the luxury market, found these headwinds in evidence. Few Asian buyers attended the show and demand came mostly from other dealers looking to acquire large diamonds, fancy colored diamonds and major gemstones.
Despite the slow market, dealers maintained they could afford to hold the line on prices, especially for fancy colored diamonds.
The impending closure of Australia’s Argyle mine, an important source for fancy pink diamonds, is giving dealers of these goods an added incentive to keep prices high.
“Once we sell them, we know we’ll never be able to replace them,” said one dealer, who believes it will bring a fundamental shift in the fancy colored diamond market. “In the past 15 years or so, we have seen many new people come into fancy colors, despite their rarity. But as this source disappears, a lot of these new people will have to change their business model or disappear.”
The increasing numbers of larger, fancy yellow diamonds from Russia and Canada is another worrisome trend for fancy colored diamond traders.
“These always provided a good cash flow (from retailers and consumers), which has allowed us to hold on to the really rare colors,” explained one exhibitor. “But with prices softening for the yellows, we may have to sell the rarer colors.” @chapter:30


Publication Year: 2023 Title: Synthetic Color-Change Wakefieldite Abstract: Figure 1. Faceted and rough synthetic wakefieldite in LED lighting with 6400K color temperature. The faceted stone is 5.04 ct. Photo by Adriana Gudino; courtesy of Arya Akhavan.
Author AA, a gemstone cutter and collector of rare synthetic gems, recently submitted one rough and one faceted stone to GIA for scientific examination. The material, sourced from RG Crystals in Bangkok, was stated to be Czochralski-pulled, neodymium-doped yttrium orthovanadate, which is commonly used in laser applications. It can also form naturally as the mineral wakefieldite-(Y), with an ideal chemical formula of YVO4. His first observation was a striking color change from pink or purple to a blue or even green color under various lighting conditions and viewing angles. The finished gemstone (figures 1 and 2) displayed strong fire due to the material’s very high dispersion.

Figure 2. The color change of the faceted synthetic wakefieldite, observed between daylight (left) and cool fluorescent light F10 (right). Photos by Aaron Palke; courtesy of Arya Akhavan.
Wakefieldite is a rare tetragonal mineral belonging to the xenotime mineral family with an ideal general formula of (REE)VO4, where REE = Y, La, Ce, and Nd among other rare earth elements. Its general physical and optical properties include a hardness of 5, specific gravity of 4.25, uniaxial + optic sign with refractive indices of nω = 2.000 and nε = 2.140, birefringence of 0.140, and dispersion of 0.084. With prominent, perfect cleavage and relatively low hardness, the material is difficult to polish. Natural wakefieldite occurs as very small, non-gem crystals unsuitable for faceting; Czochralski-pulled materials represent the only examples of faceted wakefieldite. In fact, this was the first faceted synthetic wakefieldite seen in a GIA laboratory. Chemistry and visible absorption spectra were collected to quantitatively study the striking color-change behavior.

Figure 3. The visible absorption spectra of neodymium-doped YVO4 are shown with the relative power distribution curves of CIE illuminants F10 and D65 and an Eiko warm white fluorescent bulb with color temperature of 2800K.
A polished wafer with 10.6 mm thickness was analyzed. Laser ablation–inductively coupled plasma–mass spectrometry revealed the material was composed of mostly yttrium and vanadium, with 2.2% neodymium by weight (0.03 per formula unit). Since Y3+ does not produce color on its own, the color must be derived from the addition of Nd3+ ions substituting for Y3+ ions in the crystal lattice. Figure 3 shows polarized absorption spectra in the visible range collected with an ultraviolet/visible/near-infrared spectrometer for both the ordinary ray (o-ray) and extraordinary ray (e-ray). The expected color was calculated from the absorption spectra based on the formula described by Z. Sun et al. (“Quantitative definition of strength of chromophores in gemstones and the impact on color change in pyralspite garnets,” Color Research and Application, Vol. 47, No. 5, 2022, pp. 1134–1154).

Figure 4. Color panels of the 10.59 mm wafer in six different lighting conditions were calculated for both the o-ray and e-ray. In the top row, A and D65 are CIE standard illuminants for incandescent light and daylight. Eiko is a fluorescent bulb with color temperature of 2800K, while F10 is a CIE standard narrowband fluorescent illuminant. Warm (2700K) and cool (6700K) LEDs represent the illuminants in the GIA standard viewing box.
As shown in figure 4, the material exhibited a general pink to purple to violet color in most illuminants except the Eiko warm fluorescent light and the o-ray of CIE standard illuminant F10, which represents a typical cool fluorescent light. In fact, the color-change behavior noticed by author AA could be replicated when comparing illuminant F10 to any of the other illuminants such as daylight or incandescent light. Switching between warm incandescent light and actual cool daylight did not produce a dramatic change of color. The emission spectrum of F10 fluorescent light is mainly composed of sharp peaks at 435, 545, and 610 nm (figure 3). Therefore, the color of the synthetic wakefieldite crystal under illuminant F10 is only determined by the small absorption features at ~435, 541, and 610 nm of the Nd3+ ions. Broadband emitters such as incandescent light and actual daylight (D65 in figure 3), on the other hand, do not have these sharp emission features, so the color was determined by the transmission windows in the spectrum (440–460, 490–500, 550–570, and 620–670 nm), which remain constant when switching between these illuminants. This was confirmed by observation of the stone in outdoor conditions, which produced the same pinkish purple color seen in incandescent light. The use of warm fluorescent light (Eiko fluorescent light in figures 3 and 4) with color temperature of 2800K also reproduced the greenish blue to blue color seen in cool fluorescent light (F10). It is also worth noting that the absorption features of Nd3+ ions at 541 and 610 nm were strongly dependent on the polarization of the light, resulting in a strong pleochroism (grayish purple for the o-ray and green-blue for the e-ray), only observed under F10 illuminant (figure 4).
The color panels under two LED illuminants in GIA’s standard viewing box were also calculated in figure 4. The two LED lights, warm and cool, closely imitate the CIE standard illuminants A and D65. The two sets of color panels (A = LED warm pair and D65 = LED cool pair) are extremely close to each other based on their L, C, and H (lightness, chroma, and hue) color coordinates. This study also illustrates the consistent results of GIA’s standard viewing box in grading gemstone color. @chapter:9


Publication Year: 2023 Title: Sustainability Conference at JCK Abstract: GIA participated in two panels on sustainability during the June 2023 JCK Las Vegas show. President and CEO Susan Jacques started the first panel by sharing with the audience the United Nations Brundtland Commission’s definition of sustainability: “Meeting the needs of the present without compromising the ability of future generations to meet their own needs.” A discussion covering GIA’s sustainability initiatives followed, highlighting the goal of building an inclusive and resilient future for people and the planet. These initiatives focus on social inclusion, environmental protection, and economic growth—all interconnected and crucial for the well-being of individuals and societies.
Sustainability has risen to the forefront of the gem and jewelry industry in the past ten years. A 2022 joint study by the Boston Consulting Group (BCG) and Comité Colbert estimated that 65% of consumers consider brands’ sustainability commitment when purchasing luxury products, and McKinsey & Company projected that sustainability-influenced fine jewelry sales will go from 5–10% in 2019 to 20–30% in 2025.
GIA uses scientific and research-based expertise to advance its crucial consumer-protection mission by driving transparency and bringing clarity to sustainability in the gem and jewelry value chain. In June 2023, GIA released its first sustainability report, developed in reference to the Global Reporting Initiative (GRI) framework and to the institute’s first sustainability strategy.
Looking ahead, GIA has outlined a sustainability strategy for the next two years. GIA’s 2025 sustainability strategy outlines the organization’s ambition for change, aiming to champion transparency by building resilience in the gem and jewelry sector through pioneering research and innovation, ultimately instilling greater confidence in GIA. The institute will drive change from the inside out by building an inclusive culture and reducing its climate impact. Drawing on a science-led approach, GIA plans to improve traceability through digital tools. Collectively, the institute will accelerate circularity, spearhead sustainability-related gemology research, and continue to raise awareness through responsible education programs. By working together to champion transparency and build all-important trust, GIA intends to spark real, sector-wide sustainable change.
The second panel gathered sustainability experts from across the industry: Sara Yood (Jewelers Vigilance Committee), Iris Van der Veken (Watch and Jewelry Initiative 2030), Josephine Silla-Afuwape (SCS Global Services), and consultant Christina Miller. The session began with various definitions of sustainability, followed by a discussion of how the industry collaborated on the Federal Trade Commission’s Green Guides. Panelists analyzed rising sustainability regulations in Europe and the U.S. and changing consumer behaviors. The presentation ended with key initiatives needed to start a sustainability journey. @chapter:33


Publication Year: 1991 Title: Emeralds from the Ural Mountains, USSR Abstract: Emeralds are again being mined in the historic district of the Ural Mountains. Physical, chemical, spectroscopic, and microscopic characteristics of stones from the recent production are presented and compared with data on older samples as well as those reported in the literature. Chemical analysis and visible and infrared spectroscopy provide information on crystal chemistry and color-causing trace elements that is useful both to characterize these stones and to separate them from their synthetic counterparts. A variety of mineral inclusions as well as liquid, two-phase, and three-phase inclusions were seen with magnification. All of the data are critically evaluated with respect to the confirmation of unknown samples as Uralian. @chapter:6


Publication Year: 2019 Title: CVD Layer Grown on Natural Diamond Abstract: Figure 1. Face-up image of the natural diamond with CVD synthetic diamond overgrowth. The blue color is due to the boron-doped CVD layer. Photo by Robison McMurtry.

A 0.64 ct Fancy grayish greenish blue cushion modified brilliant (figure 1) was recently found to be a composite of synthetically grown and natural diamond. During testing, the infrared spectrum showed both strong absorption of nitrogen and the absorption of uncompensated boron, features characteristic of type Ia and type IIb diamonds, respectively (figure 2). The UV-Vis-NIR spectrum showed “cape” peaks, which are nitrogen-related defects, but also a sloping absorption into the red portion of the spectrum caused by uncompensated boron. It is very unusual for boron- and nitrogen-related defects to be seen together in natural diamonds, though an example has been seen before (Spring 2009 Lab Notes, pp. 55–57). Mixed-type diamonds always call for additional scrutiny.

Figure 2. The infrared spectrum shows both nitrogen- and boron-related defects. This combination of defects is very unusual in natural diamonds and a cause for concern.
The DiamondView fluorescence image taken on the pavilion showed a blue hue, caused by luminescence from the N3 defect, and natural growth features. The image taken on the crown showed a greenish blue color common to boron-bearing diamonds and the dislocation patterns characteristic of CVD-grown diamonds. In the image taken from the side, a layer can be seen between the natural substrate and the CVD-grown addition (figure 3). These two distinct fluorescence patterns—the greenish blue from the CVD layer and the darker blue from the naturally grown layer—prove that a layer of CVD synthetic diamond was grown on a natural substrate. A wireframe model generated from a non-contact optical measurement device was uploaded to the DiamCalc diamond modeling program. Using the fluorescence images as a guide, we obtained a 3D section that represented only the CVD layer. From this, we calculated an approximate layer weight of 0.10 ct and a thickness of approximately 200 microns. A similar diamond previously reported was also a type IIb CVD layer grown on a natural Ia substrate (Summer 2017 Lab Notes, pp. 237–239). That composite was Fancy blue, weighed 0.33 ct, and had a CVD layer that was 80 microns thick.

Figure 3. A DiamondView image showing the separation plane. Image by Garrett McElhenny.
When viewed through a microscope, small pinpoint-like polish features were observed from facet to facet along with a faint line resembling surface graining. These polish features were visible along the entire area of this division and correlated with the separation plane seen in the fluorescence images. Examination with an electrical conductivity tester showed that the crown was conductive but not the pavilion. This is consistent with a type IIb crown and type Ia pavilion.

Figure 4. In immersion, the blue color of the CVD layer is clearly visible. Photo by Jonathan Muyal.
In immersion, the CVD layer was grayish blue whereas the natural substrate had a yellowish bodycolor (figure 4). The blue color in the CVD layer is from the uncompensated boron, and the yellowish color in the substrate is due to the “cape lines” in the visible spectrum. The final color, Fancy grayish greenish blue, is caused by the gray and blue components from the CVD layer and the yellow from the substrate. The resulting color was likely the main motivation for growing the CVD layer on top of the natural diamond, though the extra weight gained could also be a factor. Viewing under crossed polarizers in immersion revealed dislocation bundles that started at or near the interface and grew upward and outward (figure 5). This proves that it was a thick CVD layer and not a coating of CVD overgrowth.

Figure 5. Dislocation bundles in the CVD layer are visible under crossed polarizers in methylene iodide. Photo by Troy Ardon; field of view 1.90 mm.
In CVD-grown diamonds, there is some indication in PL spectra that the diamond has been grown in a laboratory—usually the presence of the silicon doublet peak at 736.5 and 736.9 nm or the 596/597 nm defect. Numerous PL spectra were collected in standard and confocal mode on both the crown and pavilion of the diamond in search of any indication of this synthetic overgrowth. In this case, neither of these CVD features were evident, likely due to the thinness of the layer.
With the second of these composites seen at GIA, this could be a new type of product entering the market. Earth-grown diamonds with synthetic diamond grown on the surface require extra scrutiny due to the presence of natural-looking features, both spectroscopic and gemological. Careful inspection still reveals the presence of synthetic indicators, which expose the true nature of the diamond. @chapter:11


Publication Year: 2014 Title: Natural-Color Tanzanite and Yellow Sapphire – Tucson 2014 Abstract: Figure 1. These large, reportedly unheated tanzanites possess fine color. Photos by Eric Welch; courtesy of Advanced Quality.

              At the GJX show, Kobe Sevdermish (Advanced Quality, Ramat Gan, Israel) displayed fine unheated tanzanite (figure 1), untreated yellow sapphire, and heated pink zircon.

While it is easier to buy unusual-colored tanzanite rough today, the material still is not available in abundance. Sevdermish informed us that what he calls “fancy-color” tanzanite comes from the same area as the familiar blue to bluish purple tanzanite. The rough pieces he displayed in Tucson had greenish, golden, green blue, pink, and purplish pink colors. The rarest are greens, followed by golden hues. These stones were best sellers for the company in 2013.

	Kobe SevdermishAdvanced Quality, Ltd.

	In these three videos, Israeli dealer Kobe Sevdermish introduces us to the subtle beauty of unheated tanzanite, bright yellow African sapphire much in demand among his clientele as a fancy color diamond substitute, and the rich earthy colors of heated zircon from Tanzania.
According to Sevdermish, the U.S. market is full of “regular” heated tanzanite, and people are looking for something unique. Clients are especially taken with sets where each stone displays a slightly different color. In his opinion, the luster of the unheated stones is significantly better. Sevdermish ensures that no heating is performed on any of the rough he selects. All stones are polished at the company’s factory in Bangkok.

After describing a large piece of highly transparent rough that took a week to purchase, Sevdermish showed us the two significant pieces cut from it: a 50.61 ct green-blue oval and a spectacular 19.80 ct greenish blue heart with arresting green and blue green pleochroism cut from the top part of the crystal.

	Figure 2. Precision-cut unheated yellow sapphire sold well to buyers looking for yellow diamond substitutes. Photo by Eric Welch; courtesy of Advanced Quality.
He called our attention to precision-cut unheated yellow sapphires (figure 2) arranged as sets or as precisely cut calibrated shapes, including ovals, pears, and princess cuts. Sevdermish described this corundum as a “true canary color,” which is unusual in a natural-color sapphire. He said most of the strong yellow sapphire on the market is either heated or beryllium-treated.

All the rough is carefully selected for color consistency in order to avoid greenish or grayish hues. Sevdermish estimated they select about 5% of the rough production, suitable for cutting into 2–5 mm finished stones, from a small mine in Africa. Material for 0.50 or 1 ct sizes is very rare. Sevdermish said his clients like the material because its clarity, color, and polish give it the look of fancy-color diamond.

	Figure 3. These heated Tanzanian zircons displayed a range of warm pinkish to yellowish brown colors. Photo by Eric Welch; courtesy of Advanced Quality.
Finally, Sevdermish showed us what he described as “fancy vivid” pink zircon from Tanzania (figure 3). The zircon was heat-treated, lightening the original color of the rough to reveal pinks with cinnamon tints. Further heating lightens the color a little more, producing very bright, lively stones. The only downside, Sevdermish remarked, is the name “zircon.” Customers tend to confuse the name with “cubic zirconia,” which makes them reluctant to purchase the gems until they understand that zircon is a natural stone. @chapter:1


Publication Year: 2016 Title: Hydrophane Opal Treatment Abstract: Figure 1. Top: These five opal slices of comparable thickness were cut from the same rough. They were semitransparent to translucent when viewed in daylight on a black background. Play-of-color was displayed with oblique lighting at certain angles. Bottom: The slices’ transparency improved after immersion in distilled water for approximately 20–30 minutes. Each slice absorbed water differently depending on its porosity. Photos by Nuttapol Kitdee.

Recently in GIA’s Bangkok lab, an approximately 4 cm piece of rough hydrophane opal was fabricated into five slices for various treatment experiments. Each slice was approximately 0.5 cm thick. Only clean tap water was used in the cutting process, and no other materials besides opal were involved. The opal slices showed a whitish, cloudy appearance in daylight and appeared light brown to brown in calibrated diffused light.

After the cutting step, all five slices underwent specific gravity testing, which gave SG values of approximately 1.93 ±0.03. While immersed in water, the slices displayed obvious weight gain and improved transparency, which indicated that the material was hydrophane opal (figure 1).

The water-absorbing ability of the opal was found to vary through the whole piece, resulting from its non-uniform porosity, and could be calculated as percentage weight changes in water, ranging from 5% to 13%. It took approximately one week to restore the opal’s original weight and appearance.

Two slices were then selected for oil and Opticon treatment experiments. The treatment procedures were identical. The pieces of opal were heated to approximately 80°C and then placed in warm oil or Opticon of the same temperature under vacuum conditions. They were heated continuously for 15 to 20 minutes, which was indicated by the presence of gas bubbles on the opal. Once the slices had fully absorbed the oil or Opticon, there were few, if any, gas bubbles. Afterward, the slices were removed, cleaned with a dry cloth, and left to air-dry overnight at room temperature.

Both treated opal slices were analyzed using a gemological microscope and advanced instruments. Oil treatment improved transparency but destroyed play-of-color (table 1, left). Opticon treatment enhanced transparency while preserving play-of-color (table 1, right). The FTIR spectrum of the oil-treated slice showed oil-related peaks at 5670, 5789, and 5860 cm–1, whereas the FTIR spectrum of the Opticon-treated slice displayed a series of related peaks in the 5600–5900 cm–1 range (figure 2). Raman spectra also demonstrated the presence of treatments. The oil-treated sample displayed peaks at 2929, 2897, 2873, 2851, and 2724 cm–1, while the Opticon-treated slice showed dominant peaks at 3071, 2931, and 2873 cm–1, and a series of smaller peaks in the 600–1600 cm–1 range (figure 3).

Figure 2. FTIR spectra of untreated, oil-treated, and Opticon-treated opal. The two treated
opals show characteristic FTIR peaks in the 5600–5900 cm–1 range, while untreated opal
does not show any peaks in this range.

Figure 3. Raman spectra of untreated, oil-treated, and Opticon-treated opal. The oil-treated
opal shows characteristic Raman peaks at 2929, 2897, 2873, 2851, and 2724 cm–1. The
Opticon-treated opal displays characteristic Raman peaks at 3071, 2931, and 2873 cm–1,
with a series of smaller peaks in the 600–1600 cm–1 range.
While oil and Opticon are not easily observed with the unaided eye or even with a microscope, they are readily detected by advanced instruments. Using Opticon, the process could be combined with other treatments, such as dyeing or sugar-acid treatment, to improve the durability and transparency of opal.

Acknowledgement: The authors thank Jeffery Bergman of Primagem, Bangkok for providing and performing treatment on the Ethiopian hydrophane opal samples examined in this Lab Note. @chapter:39


Publication Year: 2018 Title: Emeralds Filled with Epoxy Resin: DiamondView Observations Abstract: Figure 1. This 16.15 ct emerald was filled with epoxy resin. Photo by Lai Tai-An Gem Lab.

Emeralds from all sources routinely contain surface-reaching fissures, and as a result are subjected to clarity enhancement processes (oiling or resin filling) to improve their appearance. The quantity and variety of emerald-filling substances undoubtedly affects the final market value (M.L. Johnson et al., “On the identification of various emerald filling substances,” Summer 1999 G&G, pp. 82–107). Recently, the Lai Tai-An Gem Lab received a stone—reported as an emerald by the client—for identification services, with a request to focus on the degree of clarity enhancement. DiamondView imaging allowed us to visually explain the degree of filling in a way the client was quickly able to understand.

Figure 2. When viewed through a gemological microscope, “blue flashes” characteristic of resin-filled emeralds are clearly visible. Photo by Lai Tai-An Gem Lab; field of view 8.8 mm.

Figure 3. Characteristic epoxy resin peaks were detected at 3061, 3040, 2965, 2930, and 2870 cm–1 with FTIR spectrometry.
The transparent emerald-cut stone weighed 16.15 ct and measured 16.80 × 14.07 × 9.48 mm. It exhibited a light to medium green saturation and contained white hazy inclusions that were visible to the eye (figure 1). Standard gemological testing revealed an RI of 1.570–1.575, an SG of approximately 2.66, and a weak yellowish green reaction under long-wave ultraviolet radiation. Magnification with a gemological microscope revealed fluid and three-phase inclusions typical of natural emeralds. When turning the specimen, “blue flashes” characteristic of resin-filled material were seen within many of the fissures (figure 2). These results confirmed that the stone was a natural, clarity-enhanced emerald. Infrared spectrometry was subsequently performed to analyze the filling in more detail. Epoxy resin peaks at 3061, 3040, 2965, 2930, and 2870 cm–1 (figure 3) confirmed the epoxy resin treatment of the stone, as indicated by the initial microscopy.
Although it may not be difficult for experienced gemologists to identify various emerald-filling substances using high-end equipment like Fourier-transform infrared (FTIR) or Raman spectroscopy, we wanted to check on the suitability of another tool to assist in identifying fillers and to help see the extent and degree of filling applied. We turned to the DiamondView and obtained some interesting images for this clarity-enhanced emerald.

Figure 4. Surface-reaching fissures with greater concentrations reveal a stronger blue reaction when observed in different directions under the DiamondView’s visible light (left) and when exposed to the unit’s ultra-short-wave UV energy (right).
The stone’s surface was first observed in different directions under the DiamondView’s visible light source until obvious surface-reaching fissures appeared. Subsequent exposure to the unit’s ultra-short energy UV light clearly revealed the epoxy resin filler within the fissures as a series of blue lines extending over the entire surface against the beryl’s orange-fluorescing bodycolor. The more severe (quantity in relation to width and depth) the treated fissures were, the stronger the blue reaction (figure 4). The results of this simple test show how the DiamondView may be applied. Although the DiamondView cannot precisely identify the fillers, it does provide a means of detection that can be applied to a variety of gems. The option of ultra-short-wave radiation should be considered, as there may be concerns about the color and structural durability of host and fillers that have not been fully taken into account. @chapter:9


Publication Year: 2016 Title: Tucson: A Showcase of Colored Gemstone Innovation Abstract: Welcome to 2016’s first Gems & Gemology!

	The Tucson shows are renowned for showcasing nature’s finest gems and minerals. They’re also the venues to see imaginative use of gem materials in unfamiliar combinations. Our cover exemplifies this innovation with the “Wheel of Light”—a spectacular necklace featuring elements of sagenitic quartz, fire agate, Paraíba tourmaline, and braided leather, centered on a clear quartz disk wrapped with 24K gold. The rough gems and minerals placed inside the disk’s central axis reflect within the quartz to produce strikingly colored concentric bands. This piece amply demonstrates the ingenuity that makes the Tucson gem and mineral shows such refreshing and vital experiences. We hope you find this issue equally enjoyable.

	We offer five feature articles on diverse topics: photoluminescence (PL) spectroscopy, Australian chrysoberyl, Italian serpentine, Tajikistan’s variscite, and treated “pistachio” cultured pearls from Tahiti. You’ll also find our latest Lab Notes and Micro-World entries, along with in-depth coverage of the February 2016 Tucson shows in our Gem News International section.

	Drs. Sally Eaton-Magaña and Christopher M. Breeding of GIA’s Carlsbad lab are the authors of our lead article, which provides an overview of PL analysis and its increasing importance for detecting treatment, determining natural or synthetic origin, and verifying origin of color in type II diamonds. PL spectroscopy is now a vital tool for gemologists to authenticate the most valuable large or fancy-color gems.

		Photoluminescence spectroscopy is now a vital tool to authenticate the most valuable diamonds.

	In our second paper, a team of researchers led by Dr. Karl Schmetzer characterizes the gemological properties and growth structures of chrysoberyl recovered from the sapphire placer deposits in New South Wales, Australia.

	Two other articles cover ornamental gem materials: First, Dr. Ilaria Adamo and colleagues offer a detailed mineralogical and gemological investigation of serpentine with gem potential from Pizzo Tremogge in Val Malenco, Italy. Next, Dr. Andrey Litvinenko and his coauthors report on a largely untapped source of the ornamental mineral variscite in central Tajikistan.

	Finally, Dr. Chunhui Zhou and his team from GIA’s New York lab document the identification of treated pistachio-colored cultured pearls produced by the Ballerina Pearl Co.

	We also offer hearty congratulations to the winners of the 2015 Dr. Edward J. Gübelin Most Valuable Article Award. We’re delighted with the fantastic response to our reader ballot, which showed a significant increase in participation over last year—a big “thank you” to everyone who voted. Also, don’t forget to take this year’s G&G Challenge, our annual multiple-choice quiz.

	Please enjoy the Spring issue! @chapter:2


Publication Year: 2019 Title: Vlasovite Abstract: Figure 1. This 1.20 ct octagonal modified brilliant was identified as the rare gem vlasovite. Photo by Diego Sanchez.

The Carlsbad laboratory recently received for identification service a stone with properties that were not consistent with stones previously identified at GIA. This yellow octagonal modified brilliant (figure 1), measuring 6.41 × 5.26 × 4.68 mm, weighed 1.20 ct and had a specific gravity of 3.01. Microscopic features observed included distinct parallel twinning planes (figure 2), iridescent fractures, stringers, and fingerprints. Standard gemological testing revealed that it was doubly refractive, with a biaxial optic figure and a refractive index of 1.608–1.628. It fluoresced a very weak yellow under short-wave UV and had no reaction under long-wave UV. The Raman spectrum of the stone (figure 3) was matched to one in the RRUFF database, which confirmed the gem’s identity as vlasovite, an inosilicate mineral with the chemical formula Na2ZrSiO4O11 (rruff.info/vlasovite/R060913).

Figure 2. Colorful twinning planes were observed in the faceted vlasovite using polarized light. Photomicrograph by Jessa Rizzo; field of view 3.23 mm.

Figure 3. Raman spectroscopy confirmed the gem’s identity as vlasovite.
Vlasovite is known to be found in pegmatites in northern Russia, Canada, and Portugal. It was named after Kuzma Alekseevich Vlasov, who studied the region where vlasovite originated (handbookofmineralogy.com). Vlasovite is a rare mineral, and faceted stones are especially rare. This is the first faceted example examined at GIA’s Carlsbad laboratory. @chapter:13


Publication Year: 1957 Title: An Introduction to Spectroscopy in Gem Testing Abstract: When Isaac Newton first held a prism up to the sun, he scarcely could have imagined the influence of the spectroscope on modern gem testing. In the early 1950s, GIA’s Robert Crowningshield became expert at using this instrument to identify gems, including enhanced and imitation goods. This article shares Crowningshield’s methods, including several original drawings of spectral bands that reveal how certain gemstones selectively transmit or absorb light, yielding valuable clues to their identity. @chapter:23


Publication Year: 2017 Title: Tektite with a Large Fluid Inclusion Abstract: Figure 1. A large tektite (230.9 g) from Luc Yen, Vietnam, surrounded by six tektite samples from the GIA reference collection. Photo by Wim Vertriest.

Tektites are a form of natural glass related to extraterrestrial impact. When a meteorite hits Earth’s surface, the impact site is subjected to tremendous heat and pressure. This causes the rocks to instantly melt and quickly cool, creating a glass with a bulk composition similar to that of the original host rock. Only the most volatile elements will be removed, because their gaseous phases escape easily. This is the case for fluids and gases such as water and carbon dioxide, as well as certain metals. This melting and cooling results in a silica-dominated glass called tektite that is often very dark green to black.

Tektites are common in many parts of the world. The most famous type is probably moldavite, related to an impact in southern Germany. The world’s largest tektite area is the Australasian field, which covers Australia (australites), southeast Asia (indochinites), and most of the Indian Ocean. It is related to a single impact 790,000 years ago, although the impact crater has not been identified.

The gem mines in northern Vietnam around Thac Ba Lake, which are famous for ruby and spinel, also yield tektite from secondary deposits. Local dealer Geir Atle Gussiås (BalderGems) procured a large tektite weighing 230.9 g (figure 1) with a very large fluid inclusion. The inclusion contained a mix of gas and liquid, which could be seen under strong illumination (figure 2; see video at http://www.gia.edu/gems-gemology/tektite-inclusion). GIA’s Bangkok lab examined this unique piece by  comparing it to six tektite samples collected in the mines during several field expeditions to Vietnam.

Figure 2. A close-up view of the tektite sample using very strong backlighting reveals a curved black line, which is the liquid-gas contact. Photo by Wim Vertriest.
We examined the specimen and performed density measurements as well as chemical analysis to determine whether it was a real tektite. The surface features and overall shape of the large piece were very similar to the reference samples, although the reference samples were much smaller. The overall color was black, but when strong light was transmitted through the sample, a brown color was observed. The SG of the reference samples ranged from 2.01 to 2.42. This range can be explained by differences in chemical composition, mainly iron concentration, and the amount of gas bubbles in the matrix, which lowers the SG. The SG of the Vietnamese sample was 1.84, indicating an unusual abundance of fluid and/or gaseous inclusions in the sample. Because this tektite was too large to analyze using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), its chemical composition, along with those of the reference samples, was revealed with energy-dispersive X-ray fluorescence (EDXRF). The large tektite had Fe, Sr, Rb, and Zr contents that are comparable to the other Vietnamese tektites.

We then imaged the internal structure using real-time X-ray microradiography (RTX), a technique commonly used in pearl analysis. Because the device has a small  detector, we could not view the whole tektite in one image. The maximum resolution of 4 μm should have been sufficient to pick up any artificial structures such as drill holes. The RTX images show the irregular outline of the tektite’s surface and a large bubble with a smooth outline (figure 3). Several smaller negative inclusions are also visible as dark ovals. When the sample was moved under the RTX, the liquid-gas inclusion was clearly seen because of the motion of the liquid.

Figure 3. This RTX image shows the tektite’s irregular outline on the right side. The
very large negative inclusion has a smooth outline. Several other smaller negative
pockets can also be seen.
Since we did not find a drill hole or any signs of manmade glass, we assume that the liquid in the negative inclusion is a natural phenomenon. Since glass is not porous, it seems most likely that the liquid was included during the tektite's formation. Although this could not be proven, this tektite remains a unique specimen. @chapter:13


Publication Year: 1988 Title: Opals from Opal Butte, Oregon Abstract: Recent mining at Opal Butte in northeastern Oregon has produced a wide variety of large flawless opals. The most common gem-quality varieties are hyalite and rainbow opal, but the less common play-of-color varieties contra luz, hydrophane, and crystal opal are economically more important. Fire, blue, and dendritic opal are also found. The opal occurs in rhyolite geodes embedded in decomposed perlite. More than 100 kg of material was uncovered from November 1987 through November 1988. The opal varies greatly in stability, but the finest stable material makes excellent carvings, cabochons, and even faceted stones. @chapter:39


Publication Year: 2021 Title: A Unique Double Cat’s-Eye Emerald Abstract: Figure 1. In this 1.93 ct double cat’s-eye emerald, the chatoyant bands indicated by yellow arrows are observed from different angles of lighting. Photo by Makoto Miura.
Chatoyancy is generally produced by light reflection from numerous parallel needle-like inclusions or fibrous structures when a stone is skillfully fashioned as a cabochon. Stones such as emerald, chrysoberyl, and scapolite are known for the cat’s-eye effect (see Summer 2015 Gems News International, pp. 200–201). Recently GIA’s Tokyo laboratory examined a unique green marquise double-cabochon stone, weighing 1.93 ct and measuring 11.88 × 6.68 × 4.79 mm, that offered a particularly interesting example of chatoyancy (figure 1).

Figure 2. Emerald cabochon fashioned with a high-dome structure and ridgeline. The width of the stone is 6.68 mm. Photo by Makoto Miura.

Figure 3. Numerous parallel needles and tubes causing chatoyancy. Photomicrograph by Makoto Miura; field of view 1.75 mm.
This stone had a spot refractive index of 1.58 and a specific gravity of 2.74, and standard gemological properties indicated that it was emerald. The stone characteristically had a ridgeline and a high-dome structure (figure 2) containing numerous reflective oriented needles and tubes (figure 3) parallel to the width and perpendicular to the length of the stone. It was noteworthy that the light reflection from the inclusions created two distinct chatoyant bands along the length of the ridgeline (figure 1) under overhead light. These chatoyant bands were observed from different angles of lighting, as shown in figure 1. This double cat’s-eye effect might result from a combination of face angles, inclusions, and the high-dome cabochon structure and ridgeline.

Figure 4. The double cat’s-eye seen in the emerald results from the light reflection from oriented inclusions and the cutting style, as shown in this diagram.
Such an unusual cutting style could be responsible for creating this double cat’s-eye (figure 4). The principle of double cat’s-eye seen in this emerald is different from those of the dual-color double star effect rarely seen in ruby, sapphire, and quartz (e.g., K. Schmetzer et al., “Dual-color double stars in ruby, sapphire, and quartz: Cause and historical account,” Summer 2015 G&G, pp. 112–143). This is a unique example of an unusual optical effect due to the cutting style and inclusion scene. @chapter:19


Publication Year: 2009 Title: Ruby and Sapphire Production and Distribution: A Quarter Century of Change Abstract: During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges. This transformation was caused by the discovery of a number of large deposits and the development of treatment processes that enhanced the color and clarity of huge quantities of previously noncommercial sapphire and ruby. More recently, however, controversial treatments have undermined confidence and prices in some material, while political events and press scrutiny have affected the supply chain for rubies and sapphires from localities such as Myanmar and Madagascar. @chapter:22


Publication Year: 2015 Title: Letters: Trapiche Nomenclature Abstract: I wanted to offer hearty congratulations for the Fall 2015 issue. Robert Weldon’s cover is stunning, and the lead article on Colombian trapiche emeralds is a thought-provoking, important addition to crystallography and gemology.

I was interested in the authors’ trapiche nomenclature discussion in box A (p. 224). I understand the desire to distinguish sectoral zoning formed by inclusions or texture as “trapiche-like”; the trapiche pezzottaite reported in the Micro-World section of that same issue probably falls under that category (Skalwold and Koivula, 2015). I would argue that the cordierite-indialite intergrowths known as “cherry blossom stones,” described by the authors as “trapiche-like,” actually qualify as true trapiche growth on the basis that each sector is the result of individual crystal growth. These unique trapiches are the result of a very complex indialite-cordierite intergrowth phenomenon in which cordierite crystals grow epitaxially on the six prism faces of an indialite crystal. The latter’s remaining faces continue to grow and later alter to cordierite while grains of this intergrowth’s host accumulate along the sectors, forming the trapiche appearance. The indialite later alters to cordierite and eventually the entire intergrowth is replaced by muscovite, while retaining the outward appearance of the original mineral intergrowth (see Rakovan et al., 2006; Kitamura and Yamada, 1987).

Also, in Nassau and Jackson’s defense, I would add that later in 1970 they corrected the trapiche emerald locality information from their original American Mineralogist paper:
Based on information supplied by E.J. Tripp and L.H. Hernandez and E.J. Tripp (private communications) the actual origin of the trapiche emeralds previously attributed … to the Chivor mine is the Peña [sic] Blanca mine, near Muzo, Colombia. These have the clear center and are distinct from specimens from Muzo itself, which have a dark center. Most Peña Blanca trapiche emeralds were purchased and distributed by Mr. W.F. Bronkie, then manager of the Chivor mine, and were accordingly attributed to the Chivor locality (Nassau and Jackson, 1970). This erratum by the authors themselves is generally overlooked in articles that reference the original study.
Once again, congratulations on a superb paper, which is sure to be a classic reference across geological disciplines.

Elise A. Skalwold
Ithaca, New York
REPLY
We are glad you appreciated our work. Our judgment on “trapiche pezzottaite” can be based only on your account and not on a direct analysis of the sample. Looking at the accompanying figures, above all figure 7 on p. 327, we think that this pezzottaite sample can be classified as “trapiche-like” because the texture seems related to the zoning (probably sector zoning). There is another sample from Myanmar with similar features (http://www.mindat.org/photo-718381.html); thus, the zoning is likely due to the growth condition in this specific locality. Moreover, there are two other reasons to classify this sample as “trapiche-like”: The first is that the inclusions do not form sharp boundaries separating the equivalent sectors. The second is the absence of organic matter observed in all trapiche minerals.

We disagree with your assessment, because in cherry blossom stones the trapiche-like aspect is due to the first formation of indialite, a mineral with the same point group as beryl. As a result, they have the same growth sectors. But the formation mechanism of cherry blossom stones is completely different, and even more complex, than that of trapiche minerals. In fact, the formation of cherry blossom stones requires intergrowth, phase transition, and pseudotwinning. On the contrary, a trapiche is a single crystal where the growth sectors are separated by inclusions.

Thank you for the complementary information about trapiche emerald origin from Nassau and Jackson. We were not aware of their correction, which is never cited in the literature. At the October 2015 International Emerald Symposium in Bogotá, researchers consistently referred to Chivor trapiche emerald. We are pleased to see that our field investigations in the Chivor-Macanal-Gachala mining districts were in keeping with the correction, and that in fact trapiche emerald is only present in the western emerald zone. Your letter will help to definitively correct this error of location.

Isabella Pignatelli
University of California, Los Angeles

Gaston Giuliani
Institute of Research for Development, Toulouse, France
French National Center of Research, Vandœuvre @chapter:6


Publication Year: - Title: A Case of Mistaken Identity? Abstract: Before modern gemological testing, red spinel was often thought to be ruby. Left: Red spinel ring, courtesy of Jeffrey Bilgore. Right: Burma ruby, courtesy of Jan Goodman Co. Photos by Robert Weldon/GIA

Identifying a gemstone by color alone can lead to a case of mistaken identity, as numerous examples have shown over the course of history.
Take the most famous pretender, the Black Prince’s Ruby, for example. The large crimson, semi-polished crystal the size of an egg first appeared in 14th century Spain when King Pedro of Castille seized it from the Moorish Prince Mohammed of Granada as spoils of battle. It changed hands many times throughout the Medieval era, finally remaining in the possession of several British kings and resides in the Imperial State Crown of England.
But is the famous royal jewel identified as a ruby today?
For fun, let’s engage Hercule Poirot, Agatha Christie’s fictional Belgian detective, to investigate the identity of the Black Prince’s ruby and get his opinion.
“Observe the gem under the polarizing filter while I shine a light through the stone. At the same time, I will rotate the filter and turn the stone in several directions to avoid looking down the optic axis. Does the gem blink or change color? No, it does not. Let me explain. If this were a ruby it would blink orangey-red to purplish-red. So you see, this red stone is an imposter! It could be a spinel or red garnet.”
Being a well-read detective, Poirot knew some basic differences between rubies, spinels and garnets. He knew that when light enters a ruby, the light beam will split (double refraction) and leave the ruby as two different colors (pleochroism): orangey-red and violetish-red (dichroic; two colors). But he also knew that there is one direction in a ruby that will appear as one color. In order to see these two colors, he has to look at the stone in at least three different directions. Red spinels and garnets, however, will remain the same color in all directions, which usually means they are singly refractive.
Single refraction in red spinel and garnet is a key factor in separating them from ruby. Double refraction is a key factor for identifying ruby, and sapphire. Emerald, citrine, tourmaline, and topaz can show weak double refraction and require careful testing.
Emerald and tsavorite garnet can appear similar in color. Using the penlight and loupe to look for doubling or pleochroism would separate emerald, which is doubly refractive, from tsavorite, which is singly refractive. Also, emerald’s luster is vitreous (glass-like) to waxy while tsavorite’s is greasy to vitreous.
Determining a gem’s optic character or refraction – along with visual observations of luster, transparency, cut, heft, fracture and phenomenon, if present – are the basics of gem identification.
What Gem is it?
Test your gem knowledge. Can you guess the identity of these gemstones?

View Gallery

Color Can Be Deceiving
There are many characteristics other than color that can give clues to identification.
Inclusions
Visible inclusions using a 10x loupe could also separate emerald from garnet. Garnet usually has fewer inclusions than emerald, but if liquid or two-phase inclusions are present in emerald, they can be an identifying factor.
Separating peridot from demantoid garnet is easier if “lilypad” (unique disc-like liquid and gas inclusions found in peridot), are seen under 10x loupe magnification.
Luster and Opacity
Aventurine quartz and jade appear similar in color, but a close inspection of luster would reveal differences. Jade is dull in comparison to quartz’s vitreous nature.
Similar-looking transparent hard stones such as yellow sapphire, topaz, garnet and citrine quartz have a higher luster when polished.
A trained eye can easily see the difference of light reflecting off the surface of the sapphire, which is bright and shiny. Soft stones like yellow opal and amber will be waxy to dull in appearance. Both yellow sapphire and topaz have vitreous luster and are doubly refractive, so, advanced testing would be required to identify these gemstones.

These four blue gemstones all appear to be sapphire, but only one is! The top gem is color-change sapphire, courtesy of K & K International. From left: Kyanite, courtesy of GIA Dr. Edward Gubelin Collection; Benitoite, courtesy of B&B Fine Gems; and blue spinel, courtesy of Palagems.com. Photo by Robert Weldon/GIA
Hardness
Sapphire is very hard, registering 9 on the Mohs hardness scale; topaz is 8; citrine is 7; opal is softer at 5-6½; and amber is softest yet at 2. The amber’s heft is also noticeably lighter than other gems.
Although the instruments are simple, it takes a lot of practical observation and experience to become proficient at making separations. These principles are the foundation of modern gemology and remain at its core today. @chapter:18


Publication Year: 2022 Title: Ruby: An Expensive Mistake Abstract: Figure 1. Silk in corundum often unmixes into two different solid phases, one highly reflective (rutile) and the other of lower relief (ilmenite or hematite-ilmenite). When the Mozambique ruby was heated, the lower-relief crystals began to break down, developing irregular white patches, as shown in the yellow circle. Photomicrograph by Richard W. Hughes; field of view 1 mm.
Gemologists at Bangkok’s Lotus Gemology recently received a 6 ct ruby for identification. Declared to be an untreated ruby from Mozambique, the stone featured a superb vivid red color of a type that is often termed “pigeon’s blood” in the trade. As it was also of good clarity and well cut, it was obvious we were dealing with a gem of potentially high value.
The UV-Vis-NIR spectrum was typical for ruby/synthetic ruby. The infrared spectrum revealed peaks at 3309 and 3232 cm–1. The 3232 cm–1 peak generally indicates that a stone has been subjected to artificial heat treatment. We proceeded to examine the gem in the microscope, where we found two additional pieces of evidence of heat treatment.
The first feature was rutile silk of a type that is typical of rubies from East Africa. In these stones, the silk consists of high-relief needles of rutile with attached unidentified “daughter” crystals of another substance of lower relief. In the case of heat-treated stones, the daughter crystals will sometimes show a partial breakdown (“GIA Lab reports on low-temperature heat treatment of Mozambique ruby,” GIA Research News, April 28, 2015). Small amounts of breakdown in the form of irregular white patches were found in this stone (figure 1).

Figure 2. Spall marks on the surface of the Mozambique ruby prove it was heat treated after cutting and polishing. Note that some of the spall marks have dark halos around them. Photomicrographs by Richard W. Hughes; fields of view 2.0 and 2.5 mm.
But the most obvious evidence of heat treatment was the presence of spall marks (figure 2), which are solidified droplets of material on the surface that melted or were dissolved during heating. These spall marks across the stone showed that the ruby had been heated after cutting and not repolished following the treatment. We can only guess about the reasons for heating such a valuable gem, but there is no doubt that this particular roll of the dice was a losing gamble because the potential improvement in appearance is slight compared to the large price difference between untreated and heated ruby. We concluded that this was a heat-treated Mozambique ruby. @chapter:6


Publication Year: 2017 Title: New Azurite-Malachite Mixture from Peru Abstract: Figure 1. This polished vein of azurite with malachite and chrysocolla mined from Cochapata measures 8.5 cm wide. Photo by J. Hyršl.

Green malachite, Cu2(CO3)(OH)2, is very popular as an ornamental stone, with huge quantities coming every year from deposits in the Katanga Province of the Democratic Republic of Congo. Blue azurite has a similar chemical composition, Cu3(CO2)2(OH)2, but is much more rare. Cabochons of pure azurite are usually quite dark and not very attractive. A blend of the two is much more appealing for jewelry, but this combination is seldom found. Attractive azurite-malachite mixtures are known mainly from old finds in Bisbee and Morenci, both in the U.S. state of Arizona. There was also a find of malachite-azurite-gypsum mixture from Peru’s Moquegua region in 2012 (J. Hyršl, “Malachite-azurite from Peru,” Journal of Gemmology, Vol. 34, No. 7, 2015, p. 564).

Another new azurite-malachite mixture appeared in 2016 and was originally described as from Puno, in southeastern Peru. In fact, it is from Cochapata, in the Cotabambas Province about 50 km southwest of Cuzco, situated in high mountains. According to a dealer who visited the locality, there are several outcrops of oxidized copper veins on a steep hill exploited by artisanal miners. The veins are up to about 20 cm wide, but the parts most useful for cutting are usually only a few centimeters wide. Several tons of the rough have already been sold in Lima to foreign dealers, with the largest piece weighing 80 kg.

Figure 2. These azurite-malachite cabochons, fashioned from Cochapata material, measure up to 31 mm. Photo by J. Hyršl.
Deep blue azurite is the main mineral found today in Cochapata, accompanied by light green malachite and, less commonly, light blue chrysocolla (figure 1). The most attractive specimens have malachite with a banded structure, but some possess a brecciated structure (figure 2). The rarest samples are stalactites of malachite up to 5 cm in length. Some were sliced perpendicular to the elongated growth direction to prepare very attractive stones with an agate-like structure (figure 3).

Figure 3. A cross-section of a 25-mm-wide malachite double stalactite from Cochapata. The stalactite on the right shows malachite with an azurite center. Photo by J. Hyršl. @chapter:5


Publication Year: 2014 Title: Beryllium in Blue Sapphires, Both Natural and Diffusion-Treated Abstract: V. Pardieu, “Blue Sapphires and Beryllium: ‘An Unfinished World Quest,’” InColor, No. 23, 2013, pp. 36–43. Photo courtesy of Vincent Pardieu.

              In the early 2000s, the sapphire market was flooded with a supply of pink-orange padparadscha sapphires of unusually rich color. Upon testing, the new stones turned out to be pink sapphires that had been diffused with beryllium. Many of these treated sapphires were mistaken for natural padparadschas. The treatment was initially hard to detect, since the coloring agent penetrates deeply into the stone. It soon became evident that a full range of corundum colors were being produced.

Microscopic examination of these beryllium-treated sapphires indicated that the treatment took place at extreme temperatures (J.L. Emmett et al., “Beryllium diffusion of ruby and sapphire,” Summer 2003 G&G, pp. 84–135). The only diagnostic evidence using standard gemological equipment was. Other distinctive features proved that the stones were subjected to very high temperatures: highly altered zircon inclusions, internal recrystallization, internal diffusion around rutile crystals, synthetic overgrowth, and severely damaged crystals of unknown identity. Furthermore, the presence of color zoning that conformed to the external faceted shape of the stone suggested some level of diffusion technology.

Beryllium in Be2+ form has a very small ion; it is therefore capable of penetrating deep into the sapphire, via diffusion, during heat treatment. Light elements, such as beryllium at low ppm levels, are not easy to measure. To detect the element, laboratories needed instrumentation previously not used in gemology. Highly sensitive chemical analysis techniques, such as secondary ion mass spectrometry (SIMS), laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), and laser induced breakdown spectroscopy (LIBS) became necessary.

As author Vincent Pardieu notes, however, blue sapphire with a natural beryllium content has been reported on several occasions, in material from a variety of sources. The best way to obtain a reference stone, to be certain about the exact origin of the beryllium in sapphire, is to go to the source. That is exactly what Pardieu did during field trips that took him from Madagascar (2005) to Afghanistan (2010–2011) and Tasmania (2012) to collect samples. The samples were subjected to LA-ICP-MS for trace elemental analysis.

	Figure 1. Comet-type inclusion in a milky blue sapphire from Ampasimamitaka. The whitish tail and milky area around it were found to have a significant beryllium content. Photo courtesy of Vincent Pardieu.
Beryllium was found in clouds of minute particles in sapphires from Ampasimamitaka, Madagascar, in association with niobium, tantalum, and tungsten (figure 1). Euhedral sapphire specimens from a primary deposit in the Sar-e-Sang area of Badakhshan, Afghanistan, displayed milky areas with some beryllium and tungsten content. Finally, beryllium was associated with niobium and tantalum in the Tasmanian sapphire samples.

Sapphires from Tasmania are basalt related, while those from Ampasimamitaka and Sar-e-Sang are of the metamorphic type. In both types, beryllium was associated with other trace elements such as niobium, tantalum, or tungsten. These trace elements are lacking in sapphires treated with beryllium. This information should enable gemological laboratories to distinguish blue sapphires containing natural beryllium from beryllium-treated blue sapphires. The amount of each trace element associated with beryllium is a possible key to identifying the origin of blue sapphires with natural beryllium content. @chapter:12


Publication Year: 2022 Title: Inaugural Turquoise United Conference Abstract: Figure 1. Left: The entrance to the Turquoise Museum. Photo by Jacob Lowry/Turquoise Museum. Right: A corner in the origin display room shows rough and polished samples from Tyrone and Cerrillos, two well-known deposits in New Mexico. Photo by Tao Hsu.
The first-ever Turquoise United conference was held August 11–13, 2022, in Albuquerque, New Mexico. This multifaceted event was organized and hosted by Joe Dan Lowry and his son Jacob, part of a fifth-generation family in the turquoise industry. All activities took place in the Turquoise Museum (www.turquoisemuseum.com), owned and operated by the family and the Albuquerque Convention Center (figure 1).

Figure 2. Russell Twiford III holds a massive resin imitation of turquoise he created, which is now displayed at the Turquoise Museum. Photo by Aaron Palke.
Turquoise has been treasured and used by many different cultures for thousands of years. As an aggregate gemstone, it also poses a challenge for traders. Possibly more so than for any other gemstone, the buying, selling, and owning of a turquoise piece can be an intensely personalized experience. A combination of factors including color, matrix pattern, specific mine origin, and the presence or absence of treatment come into play, making each piece unique. Turquoise United provides a platform for everyone involved in the trade to gather as a community and discuss important topics. About 100 delegates from different countries attended the inaugural event, including miners, cutters, treatment experts, dealers, television shopping network suppliers, collectors, jewelry designers, enthusiasts, consumers, appraisers, and scientists. GIA sent research and education representatives to connect with the turquoise community and learn from the experts. We had the opportunity to interview over 10 industry experts, including members of the domestic and international trade, miners, and artisans involved in turquoise treatment and the manufacture of imitation turquoise (figure 2). The content gathered will be highlighted in future GIA educational programs.

Figure 3. Left: Attendees enjoy a conversation about Southwestern-style jewelry design and manufacture outside the Turquoise Museum. Right: Joe Dan Lowry and son Jacob were the auctioneers at the kickoff gala. Photos by Tao Hsu.

Figure 4. A 9.32 ct backed turquoise from Yungaisi, China, purchased during the auction at the Turquoise United conference. Photo by Aaron Palke.
A wide variety of activities made this educational conference enjoyable. An evening gala and auction kicked off the event (figure 3). Auction items included finished turquoise pieces, specimen and finished stone sets, and a bracelet featuring more than 200 inlay pieces designed and donated by GL Miller (Studio GL, Albuquerque). All other items were provided by the museum, and the proceeds will be allocated for future Turquoise United events. Delegates had the opportunity to view representative items from domestic and international sources such as Yungaisi, China (figure 4). All items were auctioned by the end of the gala. Each attendee received a gift bag containing a piece of turquoise, including some nice cabochons.

Figure 5. Turquoise enthusiasts and consumers brought their jewelry pieces to the identification panel experts, who shared their opinions on the pieces and answered questions from the audience. Photo by Tao Hsu.
During the day sessions, experts including Joe Dan Lowry, GL Miller, and author AP hosted identification panels at the Turquoise Museum (figure 5). Panelists evaluated the identity and origin of various turquoise jewelry pieces submitted by participants. The panel attracted consumers and enthusiasts who shared the stories behind their treasures. In the turquoise collector community, mine origin is an extremely important aspect. Turquoise enthusiasts often spend a lifetime putting together a collection of quality pieces from the most important turquoise mines, especially from the American Southwest. Lowry and Miller impressed the audience with their knowledge of historic turquoise mine characteristics, and engaged in much discussion about the complexity involved in conclusive identification and origin determination.
Two evening discussion panels took place in the Albuquerque Convention Center, with one focused on the vision and educational function of Turquoise United and the other on turquoise grading. The authors participated in both panels along with delegates from all aspects of the industry. Author TH noted the current lack of turquoise-related educational programs and the potential industry benefit of reaching a broader audience not limited just to turquoise traders.

Figure 6. Top: Joe Dan Lowry proposes a turquoise grading system alongside a panel of experts. Photo by Tao Hsu. Bottom: A look at the color scale and master stones for blue turquoise included in Lowry’s grading system. Photo by Joe Dan Lowry.
The second panel centered on Joe Dan Lowry’s proposal for a turquoise grading system that could be applied inside and outside of the turquoise community (figure 6). Lowry’s grading system is based on an unsurpassed collection of turquoise master stones of various qualities from global sources accumulated by the Lowrys over five generations. In the proposed grading system, origin is considered separately from other quality factors. A scoring system is based on a scale of 0 to 100, with the most important factor being color (70% of the final score) and additional consideration given to the aesthetics of the matrix (20%) as well as “zat” (10%), a combined description of the dynamic and boldness of both the color and the matrix patterns. Different levels of “zat” can be described as dynamic and bold in contrast to dull, flat, or uninteresting. After the quality evaluation and considering the importance of origin in many cases, the result would be combined with the condition of the piece (treated or untreated), cut, weight, and backing to give the buyer a complete picture of the stone. The panelists had a lengthy discussion on the applicability of the grading system, and author AP shared his views on consistency and potential market impact with the attendees.

Figure 7. Left: A turquoise show attendee checks out polished pieces from multiple southwestern U.S. deposits. Photo by Tao Hsu. Right: An assortment of high-quality natural Persian turquoise cabochons; the one being held weighs about 19 ct. Photo by Aaron Palke.
In addition to the educational activities, a small-scale turquoise show took place in the courtyard of the museum. A dozen dealers participated, displaying rough and finished turquoise to attendees (figure 7). To keep the event focused, dealers could only sell turquoise stones and not finished jewelry. Turquoise from the southwestern United States, Mexico, China, and Iran were all featured at the show.

Figure 8. The historic Tiffany mine in the Cerrillos mining district. This pit was mined many hundreds of years ago by Native Americans before contact with European cultures. Photos by Aaron Palke.
Surrounded by historic turquoise mines (figure 8) and Native American communities that have contributed enormously to the popularity of turquoise in the United States through their iconic turquoise jewelry designs, Albuquerque was the perfect setting for the conference. The annual Santa Fe Indian Market (SFIM), held every August, is also in close proximity. This year marks the hundredth anniversary of this famous event celebrating Native American arts and fashion, which features turquoise and turquoise jewelry. While the second Turquoise United conference is set for Albuquerque, the Lowrys are already planning future events and considering other important turquoise centers to host the conference as well. @chapter:22


Publication Year: 1984 Title: Summer 1984 Gem News International Abstract: Diamonds
            Brazil: Large Yellow Diamond Found at Coromandel
            India: First Phase of Nationwide Exploration Program Implemented
            Philippines: First Diamond-Cutting Factory Established near Manila
            Singapore: New Diamond Exchange Operational
Colored Stones
            Three New Emerald Deposits Found in Pakistan
            Gem-Quality Amethyst Rediscovered in Rhode Island, U.S.A.
            Companies Prospecting for Emeralds, Precious Minerals in Zambia
            Tanzanian Government Announces New Mining Policy
            Significant Concentrations of Beryllium Discovered in Northwest Territories
            Chrysoberyl Found in Reworked Locality in New York, U.S.A.
            Gemologically Interesting Silica Gems Discovered in Serbia, Yugoslavia
Precious Metals
            Hemlo, Ontario Area Promises to Be Important Source of Gold
            Gold-Bearing  Zone Found Near Quebec
            OK Gold Mine in Papua, New Guinea, May See Production Begin This Year
            Exploratory Drilling at Reid Mine in Northern California Reveals High Gold Values
Announcements
            Sekikazu G. Nakakura Wins 1984 George A. Schuetz Design Contest
            Geo-Literary Society Formed at Tucson
            International Exhibition (BIJORHCA) To Be Held Sept. 7-11 in Paris
            GIA GemFest ’84 Will Be Held in Santa Monica August 21 & 22

To view the full section, download the PDF above. @chapter:24


Publication Year: - Title: Pardieu Brings Ruby Rush to Life with Stories, Updates from Madagascar Abstract: Vincent Pardieu, GIA’s senior manager of field gemology in Bangkok, shared stories from his recent trip to the ruby deposit in Madagascar’s Zahamena National Park in a lecture to Carlsbad students and staff. “Gem mining is mainly about hope and hard work. Witnessing miners working gives me energy,” Pardieu said. “It’s a privilege to keep moving. When you see the way people are working … and when you have the privilege of being able to work, there is no excuse not to work hard.” Photo by Emily Lane/GIA

	A gem “fingerprint.”

	That’s what Vincent Pardieu, senior manager of field gemology for GIA in Bangkok, and his six-person team are looking for as they traverse the globe – and log hours in the lab – finding, analyzing and cataloging colored stones for GIA’s Colored Stone Identification and Origin Report reference collection.

	So when Pardieu’s team learned of a newly discovered ruby deposit in northeast Madagascar in July 2015, they arranged a field expedition and set to work investigating and documenting the rubies of the island nation’s Zahamena National Park. On Nov. 4, just a month after their trip, Pardieu and field assistant Manuel Diaz visited GIA’s Carlsbad campus to share their findings − and sometimes harrowing experiences − with students and staff.

	“To have a reference collection, you need to build it. And the best way to build it … is to send somebody to the field – to go and visit every gem mine that is known, and collect samples,” Pardieu said.

		“The two most powerful tools we have in the lab to identify if a stone is coming from this place or that place are its inclusions and trace element chemistry. But if a stone is clean (or heated), inclusions are useless … so chemistry is more powerful than inclusions because we can get chemical data from a gem any time.”

		Vincent Pardieu, senior manager of field gemology for GIA in Bangkok

Pardieu, a GIA Graduate Gemologist with a long career as a gemological researcher, tour guide and gemology writer, said that prior to recent discoveries, Madagascar was known primarily for its active sapphire mines.

A 2000 discovery “deep in the rainforest” of the eastern Andilamena district “put Madagascar on the map for rubies,” Pardieu said. And though miners carried bags brimming with the stones (“I never saw a place with so many rubies,” he said), most of them were too heavily fractured for use in jewelry without treatment. The deposit really started to be active after the discovery of the lead glass treatment in 2004. The area became known for the stones’ low quality until a 2012 discovery of sapphire and ruby near the small, remote village called Didy.

Didy’s stones were comparatively clean, beautiful and big (“I heard about rubies over 20 carats,” Pardieu said). A gem rush occurred, but mining was stopped within a few months because, unlike the previous deposit near Andilamena, that deposit was located in a protected area near three national parks.

“If the discovery was noticed by the gem trade, due to the quality of the stones produced, it was also noticed by conservation groups, who began to be very concerned about gem mining in protected areas in that country,” Pardieu said.

	Manuel Diaz, left, met Pardieu just a year earlier – as a Graduate Gemology student at GIA. He and photographer Didier Gruel accompanied Pardieu on the Madagascar expedition in the fall of 2015. Photo by Emily Lane/GIA
When he received a Facebook message last summer with photos of rubies from the area of Zahamena, he immediately started planning an expedition. The group consisted of Pardieu, cameraman Didier Gruel and Diaz, a recent GIA graduate whose 30 years as a Marine gave him experience in the jungle. The two-week trip began with challenging and even treacherous conditions, as seen in a dramatic video Pardieu showed the audience.

“We had to walk for five days in the jungle – walk, sleep and eat in the jungle – in order to reach the area with miners,” Pardieu said. “And we had to take security with us because we were informed that a lot of bandits were active in the area. If you go there as a foreigner without anybody, you will probably get attacked on the road. In many new mining areas, it’s like the Wild, Wild West.”

Once they finally arrived at the site, they discovered it was inside the Zahamena National Park, where mining is illegal. They witnessed between 500 and 1,000 informal miners working the deposit with hand tools. The arrival of such a large number of people inside the park was obviously a serious problem for people in charge of conservation in Madagascar, Pardieu said.

“It’s very important to (conservation groups) to keep places like Zahamena safe, especially [because] you don’t have a lot of forests left,” he said. "Less than 5 percent of the island still has forests, and they are very unique because the type of plants and animals there are found nowhere else on the earth.”

Most of the samples they saw were dark and quite opaque.

“You had also some stones that were nice-looking, with bright colors, and some of them were really nice,” he said. “This is a small minority – probably less than 1 percent of the production in the area, but for the informal miners it was worth the effort to come to such remote place as prices given by foreign merchants in town were attractive. We heard about some stones that were clean and over 10 carats. That is the type of stone that might one day be submitted to GIA, so we have to be able to get the reference samples because we need to be able to recognize them in the future.”

With the help of a local licensed gem merchant, the GIA team was able to acquire a range of samples from the informal miners. Back in Bangkok, they wasted no time and started to work on the samples: taking photos, cataloging them and collecting data.

They began then their search for the Zahamena rubies’ gem fingerprints.

“The two most powerful tools we have in the lab to identify if a stone is coming from this place or that place are its inclusions and trace element chemistry,” Pardieu said. “But if a stone is clean (or heated), inclusions are useless … so chemistry is more powerful than inclusions because we can get chemical data from a gem any time.”

“Nevertheless, the best way is when you have the combination of all the techniques, when you get the same result with inclusions, chemistry and spectroscopy. When everything is pointing in one direction, then you can feel quite confident about the origin of the stone,” he said.

Pardieu said that after a 15-sample analysis of the common inclusions (including unhealed fractures; long, thin silk; zircon crystals; rutile and apatite) and trace element chemistry, he was optimistic about the GIA laboratory’s ability to determine the rubies’ origin should they show up in the lab down the road.

The inclusions were “quite characteristic” of the deposit, he said. “Rubies from the Zahamena region will be in a very good position to be identified.”

Pardieu said that he sees a host of challenges and opportunities for gem mining in Africa.

“One of the questions the trade has to think about is ‘Should people just go mine everywhere?’ Obviously, the trade would benefit by promoting responsible business practices.

“There is a huge potential to associate gems – and the gemstone business – with the good guys,” he said, citing examples of companies that employ transparency efforts and finance conservation efforts.

“But the danger is that if the trade does nothing, and if illegal mining threatens places like National Parks it will be associated with the bad ones … and that would not be a good thing for our industry as we need more friends than enemies,” he said. “As a field gemologist visiting the places where gems are mined, it is quite obvious to us that what happens where the stones are mined also become important. We believe it is our duty to pass that message along − as equally important as it is to bring back samples to be able to identify the gems from this source.” @chapter:25


Publication Year: - Title: Zircon Description Abstract: Zircon comes in a wide variety of colors.

                      Colorless zircon is well known for its brilliance and flashes of multicolored light, called fire. These two zircon properties are close enough to the properties of diamond to account for centuries of confusion between the two gems.

Zircon occurs in an array of colors. Its wide and varied palette of yellow, green, red, reddish brown, and blue hues makes it a favorite among collectors as well as informed consumers.

Zircon crystals grow in many different types of rock and possess a range of optical and physical properties.

Some zircons—usually green ones—display much lower values for these properties than others. Scientists have determined that the crystal structures of these gems were almost completely broken down by radioactive elements—often present in zircon as impurities—that damaged the gems’ crystal structure over long periods of geological time.

Some gemologists classify zircons into three types—high, intermediate, and low. A zircon’s classification depends on its properties, which are directly related to the amount of radiation-induced damage done to its crystal structure.

High or normal zircons have full crystal structures, with little or no damage from radioactive elements. As a result, they have the normal physical and optical properties associated with the mineral.

In intermediate or medium zircons, radioactive elements have caused some structural damage. They have physical and optical properties that are between high and low types.

Extensive crystal-structure damage from radioactive elements results in low zircons with much lower optical and physical properties. In extreme cases, they are practically amorphous, which means they lack an orderly crystal structure.

Virtually all the zircons used in jewelry are of the high type. Interestingly, radiation-induced crystal-structure breakdown can be reversed somewhat by heating zircon to high temperatures. High-temperature heat treatment repairs the stone’s damaged crystal structure. @chapter:17


Publication Year: 2018 Title: Zircon Cluster in Ethiopian Sapphire Abstract: Figure 1. A very dense cluster of euhedral zircon associated with a larger rounded crystal of monazite, viewed under brightfield illumination. Photomicrograph by Charuwan Khowpong; field of view 1.75 mm.

Ethiopia is a known producer of opal, emerald, and commercial-grade sapphire. In March 2018, a GIA team collected a 1.911 ct blue sapphire from the Ch’ila mining area in the Tigray region. The inclusion scene shows a cluster of small transparent euhedral crystals with high relief. Raman spectroscopy identified the smaller crystals as zircon, but the clusters also contain some larger rounded monazite crystals (see above). Zircon is a common inclusion in blue sapphire, usually associated with metamorphic sources such as Myanmar, Sri Lanka, or Madagascar. Zircon inclusions from those deposits typically have more rounded shapes (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008, pp. 188–308). The sapphire deposit in northern Ethiopia is related to alkali basalt, similar to the deposits in Australia, Nigeria, or Thailand. These sources rarely show clusters of euhedral zircon crystals. The presence of these zircon clusters might help to separate Ethiopian sapphire from other basalt-related sapphire sources. @chapter:4


Publication Year: - Title: GIA Lab Reports on a New Cobalt Diffusion Treatment of Natural Spinel Abstract: This faceted cobalt-diffused spinel (left) and polished plate from another sample (right) reveal the penetration of blue color produced by the treatment.

                      Natural spinels colored by cobalt (Co) are prized for their vibrant blue hue. They’re currently in high demand with collectors and gem connoisseurs.

In May 2015, GIA laboratories in New York, Carlsbad, and Bangkok received unusual-looking, strongly colored blue spinels for identification. Other labs, including one in Sri Lanka, reported similar examples, which were determined to have undergone diffusion treatment with cobalt.

Subsequently, the Bangkok-based treater responsible for these cobalt-diffused gems provided GIA with 18 samples ranging from 0.35 to 4.99 ct for this study. He revealed some details of his treatment process, which uses “off-color” natural spinel as a starting material and reportedly involves the use of high-temperature heating with both iron (Fe) and cobalt.

GIA gemologists examined the samples using conventional microscopy, ultraviolet/visible/near-infrared (UV-Vis-NIR) spectroscopy, and analyzed their chemistry using both EDXRF (energy-dispersive X-ray fluorescence) and LA-ICP-MS (laser ablation–inductively coupled plasma–mass spectrometry). Photoluminescence (PL) spectra were also collected.

Magnification revealed features such as healed fractures and altered inclusions that indicated the stones had been exposed to high-temperature heating. The authors report that in some cases it might be challenging to determine whether the starting material is natural or synthetic, due to the highly altered nature of the inclusions. In these cases, PL spectra can help, as synthetic spinel shows distinctly broader Co-related peaks than natural spinel with this technique.

Unlike diffusion-treated corundum, most of these spinels did not show color zoning conforming to the outline of the finished gem (surface-conformal color zoning). However, when some examples were cut into sections (wafers) for LA-ICP-MS analysis, the blue color was clearly confined to the stone’s edge or rim. Additionally, the stones appeared strong red through the Chelsea color filter, as did the treated outer layers of the wafers.

UV-VIS-NIR spectroscopy revealed features characteristic of both Fe and Co, and trace-element analysis confirmed significant concentrations of both elements. Spot testing of one sample with LA-ICP-MS determined that the concentration of Co was much higher in the treated rim (466 ppma) than at the stone’s center (9 ppma). Fe concentration also appeared more elevated at the rim (up to 1070 ppma) than at the center (670–786 ppma). @chapter:19


Publication Year: 2021 Title: Faceted Demantoid Garnet with Spectacular “Horsetail” Inclusions Abstract: Figure 1. This demantoid was faceted to better reveal the “horsetail” inclusions. The sample is 8 mm in diameter. Photo by U. Hennebois.

The Laboratoire Français de Gemmologie (LFG) received for analysis an example of the yellowish green variety of andradite garnet known as demantoid. The gem was cut in such a way that spectacular “horsetail” inclusions are anchored at the center of the table (figure 1). These inclusions are actually fibers (figure 2), which are present in some demantoids from the Ural Mountains (Russia) but also from Val Malenco (Italy), Baluchistan (Pakistan), as well as from Kerman (Iran) (W.R. Phillips and A.S. Talantsev, “Russian demantoid, czar of the garnet family,” Summer 1996 G&G, pp. 100–111; Spring 2007 Gem News International, pp. 65–67; I. Adamo et al., “Demantoid from Val Malenco, Italy: Review and update,” Winter 2009 G&G, pp. 280–287; I. Adamo et al., “Demantoid from Balochistan, Pakistan: Gemmological and mineralogical characterization,” Journal of Gemmology, Vol. 34, No. 5, 2015, pp. 428–433).

Figure 2. Fibrous inclusions in a demantoid garnet. Photomicrograph by U. Hennebois; field of view 1 mm.
The exact origin and composition of the “horsetail” inclusions in demantoids are still under discussion. Those in demantoids from Russia, Italy, and Pakistan were reported to be chrysotile, and those from Iran calcite. On the other hand, a recent study of these inclusions in some demantoid garnets from the Ural Mountains showed that these might be hollow channels, sometimes containing minerals from the serpentine group, possibly the result of superficial weathering (A.Y. Kissin et al., “‘Horsetail’ inclusions in the Ural demantoids: Growth formations,” Minerals, Vol. 11, No. 8, 2021, article no. 825). Thus, the exact mechanism of formation of the “horsetail” inclusions in demantoid garnets is again open for discussion. @chapter:5


Publication Year: 2015 Title: Gem Artistry in Smaller Sizes Abstract: Sonja Kreis Unique Jewelry

In this video, Alexander Kreis displays his most recent designs: tourmalines in organic fluid shapes resembling the leaves in a tropical forest, citrines evoking the essence of sunrays, and icy blue topaz that mimic the cool brilliance of arctic ice.
At GJX, we caught up with gem artist Alexander Kreis (Sonja Kreis Unique Jewelry, Niederworresbach, Germany). It is a family business, with his father buying the rough, his mother designing the jewelry, and Alexander cutting the gems. Kreis had placed their best Oregon sunstone and their largest rutilated quartz pieces prominently in the booth to achieve a “wow” effect. Immediately beneath those signature pieces, Kreis had positioned more accessible gems that customers could use to make more affordable jewelry items. Although smaller than his trademark pieces, these were invested with the same precision and beauty. He produces pairs that would be ideal for earrings or even men’s cufflinks. Kreis spoke about three of these more accessible lines, involving tourmaline, citrine, and blue topaz.

For Kreis, green and pink tourmaline symbolize the colors of the rainforest, so their design evokes the vivid foliage and blooms of that environment. The curves provide a fluid elegance, and the cuts on the underside capture the veins and structure of tropical leaves.

Among Kreis’s new product designs for this year are citrines cut in a more angular style, with very detailed carvings on the back representing sunrays (figure 1). To Kreis, citrine’s color represents the heat of the sun, while the carvings channel its intense slanted rays.

Figure 1. Gemstone artist Alexander Kreis holds a sun carving, one of his new designs in citrine. Photo by Duncan Pay/GIA; courtesy of Sonja Kreis.
In striking contrast, another new design he called “frozen topaz” (figure 2) uses the icy hue of treated blue topaz to evoke arctic waters. The carving in the center is smoothly polished; the light rays, which are reflected from the polished carving, produce pinpoints of light on the gem’s frosted sides. The design and the material combine to produce an icy brilliance. As the wearer moves the gem, Kreis said, it produces “a harmony of light points dancing through the stone.”

Figure 2. In these examples of “frozen topaz,” the smooth carvings contrast with the frosted textures and lend an icy brilliance to the finished gems. Photo by Duncan Pay/GIA; courtesy of Sonja Kreis. @chapter:26