Title: Topaz, Aquamarine, and Other Beryls from Klein Spitzkoppe, Namibia Abstract: This article presents, for the first time, both gemological and geologic information on topaz, aquamarine, and other beryls from miarolitic pegmatites at Namibia’s historic Klein Spitzkoppe mineral locality. Topaz from Klein Spitzkoppe was first reported more than 100 years ago, in 1889. Many fine specimens have been collected since then, and thousands of carats have been faceted from colorless, transparent “silver” topaz. Gemological investigations of the topaz reveal refractive index values that are somewhat lower, and specific gravity values that are slightly higher, than those of topaz from similar deposits. In fact, these values are more appropriate to topaz from rhyolitic deposits than from pegmatites, and apparently correspond to a high fluorine content. The gemological properties of the aquamarine are consistent with known parameters. Source: GIA @topic:2


Title: Russian Synthetic Pink Quartz Abstract: Transparent crystals of facet-grade synthetic pink quartz, produced by hydrothermal growth from a fluoride solution and subsequent treatment, have been commercially available since 1994. The characteristic properties that distinguish this material from its natural counterpart are a tabular crystal morphology with two large, well-developed basal faces; color bands parallel to the basal faces and the seed plate; two-phase inclusions adjacent and perpendicular to the seed plate; and an intense broad band around 3420 cm-1 in the infrared spectrum. Color stability and cause of color in synthetic pink quartz are briefly discussed. Source: GIA @topic:2


Title: Characterization of Chinese Hydrothermal Synthetic Emerald Abstract: Synthetic emeralds grown hydrothermally in an alkali-free, chlorine-bearing solution have been manufactured in Guilin, China, since 1987. Diagnostic microscopic features include growth and color zoning as well as oriented needle-like tubes and cone-shaped voids (“nailhead spicules”) that are typically associated with small chrysoberyl crystals. Also distinctive is the presence of chlorine in this iron- and alkali-free hydrothermal synthetic emerald. In addition, spectroscopic properties in the mid- and near-infrared are useful to characterize this new Chinese product; features in the 2500–3100 cm-1 range (also found in other chlorine-bearing synthetic emeralds) help distinguish it from natural emeralds. Source: GIA @topic:3


Title: An Update on Imperial Topaz from the Capao Mine, Minas Gerais, Brazil Abstract: The Capão mine is one of the oldest and most productive fully mechanized Imperial topaz mines in the historic Ouro Preto area of Minas Gerais, Brazil. Bulldozers, water cannons, and dragscrapers are used in two main pits to remove the thick brown overburden for processing to recover topaz crystals in a broad range of sizes and colors. The rarest color is pinkish purple to purple. Heat treatment will turn some brownish yellow or orange Imperial topaz to "peach" or pink. Preliminary testing suggests that there may be a difference in fluorescence between heat-treated and non-heat-treated topaz. Source: GIA @topic:1


Title: Growth Method and Growth-Related Properties of a New Type of Russian Hydrothermal Synthetic Emerald Abstract: A new type of Russian hydrothermal synthetic emerald is produced by seeded growth in steel autoclaves without noble-metal inserts; the seed slices have been cut parallel to a face of the second-order hexagonal dipyramid s (1121). This seed orientation avoids the easily recognizable growth pattern seen in earlier Russian production. However, characteristic growth planes of a different nature—that is, parallel to s and forming a 45° angle with the optic axis—are present in the new material. Source: GIA @topic:3


Title: Copper and Tenorite Inclusions in Cuprian-Elbaite Tourmaline from Paraíba, Brazil Abstract: Inclusions of native copper and tenorite (CuO) were found in grayish green elbaite from São José da Batalha, Paraíba, Brazil. Native copper forms strongly dendritic platelets (about 100 µ long, 1 µ thick) oriented parallel to the c-axis of the host crystal in a trigonal arrangement. The much less abundant tenorite forms 20-30 µplaty grains. Electron microprobe analyses revealed that the tourmaline is cuprian elbaite (1 wt. % CuO), with significant contents of iron (2.7-3.1 wt. % FeO) and manganese (0.9-1.4 wt. % MnO). The CuO content of tourmaline around the native copper decreases toward these inclusions up to a factor of two. No such decrease in CuO was observed for the tenorite inclusions. Source: GIA @topic:12


Title: Synthetic Rubies by Douros: A New Challenge for Gemologists Abstract: Greek manufacturer J. & A. Douros introduced a new flux synthetic ruby in early 1993. Grown by spontaneous nucleation in a lead-based solvent, the Douros synthetic ruby occurs as rhombohedral single crystals and twinned tabular crystals, as well as in clusters. The tabular crystals typically have intense red cores that gradually decrease in saturation to a near-colorless outermost layer; the rhombohedra1 crystals have a deep red body and a thin near-colorless laver on the rhombohedral faces, with umbrella-like growth patterns in some areas. Some samples contain distinctive inclusions of yellow residual flux with spherical bubbles. Chemically, the crystals are heavily zoned, and EDXRF analyses revealed variable trace amounts of Ti, Fe, Cr, and Ga, as well as some Pb. SEMEDS identified the flux particles as lead bearing. Microprobe analyses showed high Cr values in the crystal cores; in certain growth zones, Fe replaces Cr in the outermost layers. If inclusions or typical growth structures are not present, chemical composition appears to be the best means of separating these Douros synthetic rubies from natural rubies. Source: GIA @topic:3


Title: Rubies from Mong Hsu Abstract: Large quantities of rubies—both rough and faceted—from a commercially important new source in Myanmar (Burma) have been available on the Bangkok market since 1992. The ruby crystals from the Mong Hsu marble deposit have dipyramidal to barrel-shaped habits and reveal dark violet to almost black “cores” and red “rims.” With heat treatment, which removes their blue color component, the cores become intense red. The rubies grew under varying conditions in complex growth sequences. The color distribution between cores and rims is related to a different incorporation of chromium and/or titanium during crystal growth. Gemological, microscopic, chemical, and spectroscopic properties presented here permit the separation of faceted Mong Hsu rubies from their synthetic and other natural counterparts. Problems arising from artificial fracture fillings are also addressed. Source: GIA @topic:1


Title: Sapphires from Changle in Shandong Province, China Abstract: Sapphires were recently found in alluvial deposits and in situ in basaltic rocks near Wutu, Changle County, in central Shandong Province. The fact that significant amounts of sapphire have been found in situ at Changle makes it unique among sapphire deposits in basaltic terrains around the world. (Sapphires have been found in situ elsewhere, but never in such abundance in basalt.) Changle sapphires occur in a range of colors (dark blue, blue, greenish blue, and yellow), but they are predominantly dark blue. Fe, Ga, Ti, Co, and V are the most abundant trace elements present. The gemological properties of Changle sapphires are consistent with those from similar alkalic basalt environments. Source: GIA @topic:1


Title: A Gemological Look at Kyocera's New Synthetic Star Ruby Abstract: Kyocera Corporation of Kyoto, Japan, is currently marketing under the trade name "Inamori" a macroscopically natural-appearing semitransparent asteriated synthetic ruby. With the exception of obvious internal characteristics and a relatively strong fluorescence to ultraviolet radiation, all of the gemological properties shown by this material are essentially the same as those encountered in natural star rubies. For the majority of gemologists without access to research- grade testing equipment, the internal characteristics of Kyocera's synthetic star ruby are the only universally reliable means of identifying this new product. Source: GIA @topic:3


Title: Examination of Three-Phase Inclusions in Colorless, Yellow, and Blue Sapphires from Sri Lanka Abstract: Three-phase inclusions in untreated natural colorless, yellow, and blue sapphires from Sri Lanka were found to consist of liquid and gaseous carbon dioxide as well as needle-like to tabular crystals of diaspore. The identification of diaspore was accomplished through the use of a microscope-mounted drill system and an improved version of the Gandolfi X-ray camera. Technical details for both methods are given. The conditions under which diaspore forms as a daughter mineral in corundum are briefly discussed. Source: GIA @topic:3


Title: Inamori Synthetic Cat's-Eye Alexandrite Abstract: The world's first commercially available synthetic cat's-eye alexandrite chrysoberyl is now being manufactured and marketed by the Kyocera Corporation in Kyoto, Japan. Kyocera markets synthetic gemstones in the United States under the trade name "Inamori Created." This article reports on a detailed gemological examination of this new synthetic cat's-eye alexandrite. Although most of the gemological properties of this new synthetic overlap those of natural cat's-eye alexandrite, it can be identified by its unique internal characteristics and its unusual fluorescence to short-wave ultraviolet radiation. Source: GIA @topic:3


Title: A Study of the General Electric Synthetic Jadeite Abstract: The gemological properties of synthetic green and lavender jadeite, which has been manufactured by the General Electric Company on an experimental basis, are summarized. The synthetic jadeites examined appear as flattened or rounded disks that have indices of refraction of about 1.66 and specific gravities of 3.28-3.34. They are also similar in many other respects to natural jadeites, except for a slightly greater hardness (-8) and differences in luster, translucency, and appearance. The synthetic jadeites are the result of an experimental study, and at present there are no plans for commercial production. Source: GIA @topic:13


Title: Unstable Radiation-Induced Yellow-Green Color in Grossular Garnet Abstract: Although conventional wisdom has been that irradiation will not alter the color of garnets, exposure of some colorless to pale-hued African grossulars to either 60Co or 137Cs gamma rays turns them light yellow-green. The resulting color is unstable and fades within hours to days in sunlight, and within weeks in the dark. The spectra of the radiation-enhanced garnets differ from those of similar-appearing naturally colored grossulars. In the dark, the irradiation-related absorption features undergo two stages of fading: an initial period of relatively rapid fading, followed by a longer period of slow fading. In daylight, a single rate of even faster fading is observed. Source: GIA @topic:3


Title: Emeralds of the Panjshir Valley, Afghanistan Abstract: With the withdrawal of Soviet troops from Afghanistan, villagers in the Panjshir Valley are turning their attention to the emerald riches of the nearby Hindu Kush Mountains. Large, dark green crystals have been found in the hundreds of tunnels and shafts dug there. Teams of miners use explosives and drills to remove the limestone that hosts the emerald-bearing quartz and ankerite veins. The gemological properties of Panjshir emeralds are consistent with those of emeralds from other localities; chemically, they are most similar to emeralds from the Muzo mine in Colombia. "Nodules," previously reported only in tourmaline and morganite, have been found in Panjshir emeralds as well. Approximately $10 million in emeralds were produced in 1990; future prospects are excellent. Source: GIA @topic:1


Title: An Extraordinary Calcite Gemstone Abstract: A 1,156-ct calcite gemstone cut from a twin crystal presents an unusual phenomenon when the interior is viewed through the table. One observes a multitude of colored images of the lower pavilion facets that change position and color with change in the viewing angle. This kaleidoscopic effect results in part from dispersion and the high birefringence of calcite, but the large number of facet images is caused by the twinning. As a single light ray enters the table, it is broken into two rays, O and E. On crossing the twin plane, each of these rays is divided into O and E rays, resulting in four rays that are reflected across the pavilion to be reflected toward the table. On this upward path, the rays again cross the twin plane and once more are divided into new O and E rays. Thus a single entering light ray emerges as four O and four E rays. Source: GIA @topic:3


Title: Gemstones with Alexandrite Effect Abstract: The term alexandrite effect refers to the apparent change of color in certain minerals from blue-green or greenish violet in daylight to red or reddish violet in incandescent light. This effect was discovered in chrome-bearing chrysoberyl from the Ural Mountains as early as the beginning of the 19th century. In more recent times, it has also been observed in certain varieties of garnet, corundum, spinel, kyanite, fluorite, and monazite. It has been determined that the absorption spectrum of all alexandrite-like minerals is characterized by transmission maxima in the blue-green and red regions and by a transmission minimum in the yellow region. The color of minerals with two such regions of transmission is determined in daylight (richer in blue and green) by the position of the transmission maxima and in incandescent light (richer in red) by the ratio of transmission in the red and transmission in the blue-violet sections of the visible spectrum. Source: GIA @topic:3


Title: Identification of Chromium-Bearing Red Gemstones Using Photoluminescence: A Red Musgravite Case Study Abstract: Figure 1. A 1.59 ct red musgravite. Photo by Shunsuke Nagai.

Figure 2. The PL spectrum of the red musgravite consisted of two very strong peaks at 685.7 nm (R1) and 686.8 nm (R2 or L). In the spectrum below that, its weak side peaks are expanded by multiplying the intensity by 20. They are partially similar to those of ruby (692.9 (R2) and 694.4 (R1) nm), its expanded weak side bands, and a red spinel (685.5 (R) and 687.1 (L) nm). Spectra are offset vertically for clarity.
Photoluminescence (PL) provides us with useful information to understand physical properties of gem materials and can also be used for gem identification and treatment detection. For example, a 1.59 ct red musgravite (figure 1) that had previously been examined by the Central Gem Laboratory in Japan (Z. Zhenghao et al., “A remarkable Cr-bearing red musgravite,” Journal of Gemmology, Vol. 38, No. 6, 2023, pp. 548–551) was also submitted to GIA’s Tokyo laboratory for identification. Its standard gemological properties (refractive index, specific gravity, dichroism, and UV fluorescence reaction), Raman spectrum, and ultraviolet/visible spectrum were consistent with musgravite. The chemical formula was measured as Be1.21(Mg1.95, Fe0.01, Zn0.02)Al5.86O12 by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) with a chromium concentration of 1360–1840 ppm (table 1). A PL spectrum for musgravite (figure 2) was also collected with a 532 nm laser and consisted of two strong peaks and weak side bands. Interestingly, the positions of the strong peaks were close to those caused by chromium in spinel, but the overall pattern was similar to that caused by chromium in ruby or sapphire. PL emission spectra are collected by exposing a material to strong short wavelength light, creating excited energy states in the material. These excited energy states then relax and return to a ground state by emitting light at a longer wavelength than the excitation wavelengths. The light collected during this relaxation is the PL spectrum. Trace amounts of chromium in many materials can easily enter these excited energy states and produce characteristic PL spectra in different gems such as ruby, spinel, and musgravite.

Figure 3. Polyhedral representations of the crystal structures of (A) reported musgravite, BeMg1.63Fe0.37Al6O12 (Nuber and Schmetzer, 1983); (B) typical corundum, Al2O3; and (C) normal spinel, MgAl2O4. Thin black lines depict the unit cells. The green tetrahedra are BeO4. The orange tetrahedra and octahedra are MgO4 and MgO6, respectively. The blue tetrahedra and octahedra are AlO4 and AlO6, respectively. In musgravite, the AlO6 octahedra have three types: one undistorted (Al1) and two differently distorted (Al2 and Al3).
In this report, we investigated the reasons why these PL spectra differ between red musgravite, ruby, and spinel. The two strong peaks at 685.7 and 686.8 nm of the red musgravite are referred to as zero-phonon lines (ZPLs) that do not contain the energy of “lattice vibrations,” which are the motions of atoms around their equilibrium positions. These peaks result from the transition from the lowest excited state to the ground state of three 3d orbital electrons of the Cr3+ ion replacing the Al3+ ion at the center of oxygen polyhedra, as in ruby and red spinel. The crystal structure of musgravite includes one type of AlO4 tetrahedron and three types of AlO6 octahedron: one undistorted and two differently distorted; see figure 3A, drawn using VESTA software (K. Momma and F. Izumi, “VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data,” Journal of Applied Crystallography, Vol. 44, 2011, pp. 1272–1276) and the reported crystal structure data (B. Nuber and K. Schmetzer, “Crystal structure of ternary Be-Mg-Al oxides: taaffeite, BeMg3Al8O16, and musgravite, BeMg2Al6O12,” Neues Jahrbuch fur Mineralogie, Monatshefte, 1983, pp. 393–402). The chromium PL emission is split into two strong lines, due to either the distortion of the AlO6 octahedron as in ruby and sapphire, or the occupation of multiple crystal sites by chromium. The position of the red musgravite is shorter in wavelength than in ruby and sapphire but almost equal to that of red spinel. This means the energy difference between the excited and ground states is greater than that in ruby and close to that in red spinel.
The chromium PL spectrum for musgravite shows additional small peaks at longer and shorter wavelengths, termed “phonon sidebands” and “Urbach tails,” respectively (again, see figure 2). If the intensity of the main ZPLs is a large proportion of the total luminescence intensity, it indicates that the Debye-Waller factor, representing the magnitude of atomic vibrations in a crystal structure, is small. The weak sidebands on both sides of the red musgravite indicate that the Debye-Waller factor is smaller than that of red spinel but similar to ruby.
PL spectroscopy on chromium-bearing gemstones is not only one of the most powerful tools for quick and nondestructive identification but also a means to obtain interesting physical properties of rare gemstones by comparing with the PL spectra of familiar gems. Furthermore, the difference in degree of the Debye-Waller factor may be one of the reasons why the presence or absence of heat treatment can be detected by PL in spinel (S. Saeseaw et al., “Distinguishing heated spinels from unheated natural spinels and from synthetic spinels: A short review of on-going research,” https://www.gia.edu/doc/distinguishing-heated-spinels-from-unheated-natural-spinels.pdf, April 2, 2009), but not in corundum. Source: GIA @topic:3


Title: Dyed Bone as a Red Coral Imitation Abstract: Figure 1. This 8.86 ct orange-red cabochon, submitted as coral, was identified as dyed bone. Photo by Gagan Choudhary.

Numerous materials have been widely used to imitate red coral: glass, plastic, ceramics, composites, and dyed shells. Recently, the Gem Testing Laboratory in Jaipur examined an 8.86 ct orange-red cabochon measuring 16.56 × 12.19 × 7.34 mm (figure 1) that was presented as red coral but proved to be dyed bone, an unusual imitation.
Initial observation showed a strong resemblance to red coral, but careful microscopic observation proved otherwise. The sample lacked the typical “tree ring” or striated growth structure seen in corals, though it did display a network of fine veins throughout. Viewed from above, these veins appeared subparallel and were oriented along the length of the cabochon (figure 2). The veins also displayed orange-red color concentrations against the cabochon’s whitish bodycolor (again, see figure 2), suggesting that the material was both dyed and organic.

Figure 2.  The dyed bone displayed subparallel veins oriented along the length of the cabochon; also note the orange-red color concentrations against the sample’s whitish bodycolor. Photomicrograph by Gagan Choudhary; magnified 48×.
Detailed observations of the sample from all sides revealed that the subparallel veins were confined to circular concentric planes oriented along the length of the cabochon (figure 3, top); the individual veins were further surrounded by concentric whitish rings (figure 3, bottom). These structural features ruled out the possibility of coral, but the identity had yet to be established.

Figure 3. Subparallel veins were confined to circular concentric planes oriented along
the length of the cabochon (top), while the individual veins were surrounded by concentric whitish rings (bottom). Photomicrographs by Gagan Choudhary; magnified 40× (top) and 56× (bottom).
The sample’s spot RI was approximately 1.56, without any noticeable birefringence blink, while its hydrostatic SG was 2.01. Under a UV lamp, it displayed pinkish orange patchy fluorescence (which was stronger under long-wave UV). This characteristic is typically associated with dyes. Qualitative EDXRF analysis revealed the presence of phosphorus and calcium. Chemical, gemological, and observational features indicated bone, which was further confirmed by Raman spectroscopy. Raman spectra (figure 4) obtained using a 785 nm laser in the 200–2000 cm–1 region displayed a strong peak at approximately 960 cm–1, with weaker peaks at approximately 430, 586, and 1072 cm–1. Also present were a few indistinct features in the 1200–1700 cm–1 region. The peaks at approximately 960, 586, and 430 cm–1 were attributed to PO3–4 bending and stretching, and the one at 1072 cm–1 to CO3–4 stretching. The indistinct features between 1200 and 1700 cm–1 were due to collagen—the essential component of bone tissue (C. Kontoyannis et al., “Analysis of bone composition with Raman spectroscopy,” Proceedings of the 13th Panhellenic Pharmaceutical Congress, 2012, http://nemertes.lis.upatras.gr/jspui/bitstream/10889/5187/1/PMO031.pdf).

Figure 23. The bone’s Raman spectrum showed major PO3–4 peaks at about 960, 586, and 430 cm–1; a CO3–4 peak at 1072 cm–1; and collagen-related peaks in the 1200–1700 cm–1 region.
Bones have been used as jewelry since ancient times, and some specimens are dyed or stained to make them appear older (Summer 2006 Lab Notes, p. 160). Bone is used to imitate ivory, but this is the first time we have seen a bone dyed red and presented as coral, an interesting and unusual imitation. Although the market penetration of this material is unknown, we cannot rule out the possibility of it being mixed in packets of red coral, and this separation would pose a challenge for jewelers and gemologists. Source: GIA @topic:14


Title: Mobile Fluorite in Quartz Abstract: Figure 1. This violet-colored fluorite crystal was free to move in its octahedral void, as seen in four different positions. Photomicrographs by Nathan Renfro; field of view 7.18 mm.

	In 2005, a deposit in Madagascar yielded quartz that showed beautiful blue to purple octahedral fluorite crystal inclusions (Summer 2005 GNI, pp. 180–181). This author recently examined a unique example of this material in which a fluorite crystal was much smaller than the cavity it occupied (figure 1). The difference in size allowed the fluorite to move freely within the void. Also present in the void and surrounding the fluorite crystal were an aqueous liquid and a small gas bubble. Because the cavity was an octahedron, a shape not related to quartz morphology, it is assumed that the fluorite was originally much larger and defined the shape of the void while in that larger state. Also observed was a secondary healed crack that broke from the surface of the quartz to the void while it was still in the growth environment. This crack allowed fluids that were not in equilibrium with the fluorite to partially dissolve it before the crack healed, trapping the much smaller fluorite remnant in the void. Mobile inclusions in gems such as this example are rare and fascinating to observe. Source: GIA @topic:2


Title: Rain Cloud in Alexandrite Abstract: An alexandrite seen with fine milky particles and bands of silk resembling a rain cloud. Photomicrograph by Britni LeCroy; field of view 2.90 mm.

An example of nature imitating nature was seen in a 0.73 ct faceted alexandrite showcasing an inclusion reminiscent of a rain cloud (see above). The “cloud” was composed of white particles oriented as parallel bands that displayed a cloud-like silhouette when viewed at an angle. The “rain” was composed of fine oriented reflective needles commonly referred to as silk. Fiber-optic lighting allowed for a concentration of white light to be seen under the cloud, creating an appearance of lightning. The inclusion scene observed in this gem is an interesting novelty that any gemologist can appreciate. Source: GIA @topic:3


Title: Chlorapatite in Quartz Abstract: Figure 1. This 57.56 ct rock crystal quartz hosts two large euhedral chlorapatite crystals. Photo by Kevin Schumacher.

We recently examined a 57.56 ct rock crystal quartz (figure 1) that came from Luciana Barbosa (Gemological Center, Asheville, North Carolina). Said to be from Bahia, Brazil, the transparent and colorless rectangular step-cut gem measured 31.91 × 19.01 × 11.83 mm and hosted two relatively large translucent euhedral crystals. When examine under magnification, these inclusions appeared to be hexagonal prisms, the larger one measuring approximately 7.0 mm in length. Rotation of the microscope’s analyzer clearly displayed the crystals’ dichroism, which changed from blue to pale yellow (figure 2). Laser Raman microspectrometry was used to identify the inclusions as chlorapatite. This is the first time that we have encountered chlorapatite as a inclusion in quartz.

Figure 2. The blue and pale yellow dichroic colors of a chlorapatite inclusion in quartz are clearly seen in these microscopic views. Photomicrographs by Nathan Renfro; field of view 14.16 mm. Source: GIA @topic:2


Title: Gilson Cat’s-Eye Synthetic Emerald Abstract: Figure 1. This 2.73 ct Gilson synthetic emerald cabochon displays a sharp “cat’s-eye” phenomenon. Photo by Kevin Schumacher.

In the early 1960s, French ceramist and engineer Pierre Gilson succeeded in growing and producing flux synthetic emerald of commercially marketable quality. By the mid-1970s, it was reported that Gilson commanded 95% of the world market in synthetic emeralds (J. Sinkankas, Emerald and Other Beryls, Chilton Book Company, Radnor, Pennsylvania, 1981, p. 308). While the Gilson factory is no longer active, the material is still occasionally encountered in the trade and in gemological laboratories. The authors recently examined one example, a 2.73 ct cabochon that was of particular interest for its chatoyancy (figure 1).
Gilson synthetics are often grown from seed plates of slices of natural beryl positioned parallel to the c-axis. Microscopic examination of the specimen revealed veils and wispy secondary flux fingerprint inclusions, as well as strain bands like graining aligned parallel to the c-axis, all common features of Gilson synthetic emerald. The numerous growth striae resulted from inner strain, caused by periodic growth interruptions or slight changes in chemical composition when the growth tank was recharged (Sinkankas, 1981; R. Diehl, “Neues zum Thema ‘Synthetischer Smaragd’: Besuch bei Pierre Gilson,” Zeitschrift der Deutschen Gemmologischen Gesellschaft, Vol. 26, No. 2, 1977, pp. 61–75).

Figure 2. The parallel arrangement of a network of primary flux inclusions is responsible for the cat’s-eye effect. Photomicrograph by Jonathan Muyal; field of view 2.77 mm.
Also parallel to the c-axis (the basal pinacoid of the original crystal), we observed a plane of tubes (figure 2) that was responsible for the chatoyant effect. This plane of numerous elongated bubbles/cavities containing the primary flux—and possibly minute phenakite crystals—was located near the base of the cabochon. This oriented plane of primary flux tubes also appears to result from the variation of conditions during growth.
The micro-world of flux-grown Gilson emerald has already been captured extensively (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 3, Opinio Publishers, Basel, Switzerland, 2008). But the interest of this specimen is its clever fashioning, with the plane of the coarse primary flux residue—which a lapidary would normally want to remove—oriented close to the base and parallel to it, turning this into a chatoyant specimen. In fact, this is the first time a Gilson flux-grown cat’s-eye emerald has been encountered by the authors. Source: GIA @topic:3


Title: Laboratory-Grown Sapphire with Unusual Features Abstract: Figure 1. This 14.36 ct pink-orange synthetic sapphire contains large fractures with orange staining and some partially crystallized foreign material. Photomicrograph by Moqing Lin; field of view 15.26 mm.

The Hong Kong laboratory recently examined a 14.36 ct pink-orange cushion mixed-cut specimen measuring 12.97 × 11.41 × 10.59 mm. Standard gemological testing yielded an RI of 1.760–1.768, a chromium emission line in red using a handheld spectroscope, strong red fluorescence under long-wave UV, and weak red fluorescence under short-wave UV. These properties were consistent with pink sapphire. Magnification revealed large fractures containing orange staining and some partially crystallized foreign material (figure 1). The foreign material partially crystallized in a dendritic pattern resembling that of diaspore (figure 2). Other natural-looking features included a twinning plane and tubules. Nonetheless, the observation of indistinct Plato lines and a slight curvature in the twinning plane raised suspicion about the stone’s nature.

Figure 2. The foreign material partially crystallized in a dendritic pattern in the fractures, reminiscent of diaspore. Photomicrograph by Moqing Lin; field of view 7.64 mm.

Figure 3. The pink-orange specimen showed a strong red curved band in the DiamondView, confirming its identity as a flame-fusion synthetic sapphire. Image by Moqing Lin.
A strong red curved band observed in the DiamondView confirmed it was a Verneuil (flame-fusion) synthetic sapphire (figure 3). The absence of Ga, V, and Fe in the specimen, determined using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), provided further evidence supporting its synthetic nature. Ti was below detection limit in all six spots. Cr was below the detection limit in one spot and 37.61–44.31 ppma in five other spots.
Although flame-fusion synthetic sapphires are common in the marketplace, it is unusual to encounter a specimen containing such natural-looking orange staining and partially crystallized foreign material in the fractures. Careful observation as well as advanced testing are required for the correct identification of the natural or synthetic origin of such specimens. Source: GIA @topic:3


Title: Synthetic Rock Crystal Quartz Bangle with Unusual Inclusions Abstract: Figure 1. A synthetic rock crystal quartz bangle measuring approximately 80 × 22 × 10 mm. Photo by Nuttapol Kitdee.

Synthetic quartz is grown by the hydrothermal technique, which can produce large single crystals of high quality (K. Byrappa and M. Yoshimura, Handbook of Hydrothermal Technology: A Technology for Crystal Growth and Material Processing, William Andrew Publishing, 2001). This process, widely used in the jewelry trade, has led to difficulty in separating synthetic quartz from its natural counterpart (R. Crowningshield et al., “A simple procedure to separate natural from synthetic amethyst on the basis of twinning,” Fall 1986 G&G, pp. 130–139). The presence of Brazil-law twinning and certain inclusions, such as tourmaline or golden rutile needles, can be used to distinguish natural from synthetic quartz. But high-quality quartz, whether of natural or synthetic origin, typically has no inclusions or twinning. In this case, standard gemological testing may not be able to identify the origin. Advanced instruments, including infrared absorption spectroscopy (S. Karampelas et al., “An update in the separation of natural from synthetic amethyst,” Bulletin of the Geological Society of Greece, 2007, pp. 805–814) and LA-ICP-MS are considered useful tools for separating natural from synthetic material from material with synthetic origins (C.M. Breeding, “Using LA-ICP-MS analysis for the separation of natural and synthetic amethyst and citrine,” GIA News from Research, 2009).

The Bangkok lab recently examined a high-clarity, transparent, near-colorless bangle (figure 1). Standard gemological testing revealed a spot RI of 1.54 and an SG of 2.65, consistent with quartz. Magnification revealed irregular two-phase inclusions (figure 2). These inclusions are more likely to be present in natural quartz than in hydrothermal synthetic quartz, which typically shows nail-head spicule and breadcrumb inclusions. This bangle also gave an IR absorption spectrum unlike that of natural rock crystal quartz. The characteristic IR absorptions of natural rock crystal quartz occurred at 3379, 3483, and 3595 cm–1. These features are never seen in synthetic rock crystal quartz. The IR spectrum of the bangle showed absorption peaks at 3610, 3585, 3431, 3294, and 3194 cm–1 (figure 3), which matches the IR absorption features of synthetic rock crystal quartz (P. Zecchini and M. Smaali, “Identification de l’origine naturelle ou artificielle des quartz,” Revue de Gemmologie, No. 138/139, 1999, pp. 74–80). The IR spectrum confirmed that this material was grown by hydrothermal methods.

Figure 2. Irregular two-phase inclusions seen in the bangle using darkfield illumination (left and right) are similar to those found in natural specimens but are rarely found in hydrothermal synthetic quartz. Photo by Nattida Ng-Pooresatien; field of view 4.1 mm.

Figure 3. Infrared spectra of the synthetic rock crystal quartz bangle and a 17.50 ct natural
rock crystal quartz faceted bead show different absorption patterns. The characteristic
absorptions of natural rock crystal quartz at 3379, 3483, and 3595 cm–1 are never seen
in synthetic rock crystal quartz. The bangle showed absorption peaks at 3610, 3585,
3431, 3294, and 3194 cm–1, matching the IR absorption of synthetic rock crystal quartz.
Large transparent colorless quartz can be found in natural and synthetic forms, but synthetic quartz is usually seen as a flat crystal. This bangle is an interesting example of large, high-clarity synthetic quartz used in jewelry. The presence of the irregular two-phase inclusions in this example serves as an important reminder that natural and synthetic quartz can show a similar appearance and contain internal inclusion features that are identical. Source: GIA @topic:2


Title: Application of the DiamondView in Separating Impregnated Jadeite Abstract: Figure 1. The two jadeite samples exhibited a mottled dark and light green bodycolor (left, 4.91 ct oval) and a uniform lighter green bodycolor (right, 0.32 ct pear). Photos by Lai Tai-An Gem Lab.
Infrared and Raman spectroscopy are frequently used to separate impregnated jadeite jade from untreated material. Recent trials show that the DiamondView instrument provides reliable results in detecting impregnated material, offering gemologists a new identification method.

The Lai Tai-An Gem Lab in Taipei analyzed two client-submitted jadeite samples (figure 1): a 4.91 ct oval measuring approximately 19.64 × 11.78 × 2.62 mm and a 0.32 ct pear-shaped drop measuring 7.77 × 5.91 × 0.95 mm. The oval possessed a mottled dark and light green bodycolor, while the pear shape exhibited a more uniform, lighter green bodycolor. Both pieces were translucent. Standard gemological testing showed spot RIs of 1.66 and SGs of 3.30 for the oval and 3.24 for the pear. A handheld spectroscope revealed lines at 630, 655, and 691 nm, indicative of naturally colored jadeite; both samples were inert to long-wave and short-wave UV fluorescence. Microscopic observation revealed fine surface-reaching networks of cracks and uncovered the “cobweb-like” features characteristic of bleached jadeite. However, DiamondView imaging produced striking blue reactions (figure 2), clearly indicating that both jadeites had been impregnated.

Figure 2. DiamondView imaging of the jadeite samples. Top: Both the oval (left) and the pear shape (right) displayed the “cobweb” feature under visible light. Bottom: The DiamondView’s UV light produced striking blue reactions in the cobweb structure, indicating impregnation in both jadeites. Images by Lai Tai-An Gem Lab.
We confirmed that the samples were impregnated jadeite using the advanced methods commonly applied in such cases. FTIR spectroscopy revealed absorptions at 3061, 3037, 2965, 2925, and 2874 cm−1 (figure 3), while Raman spectroscopy using a 532 nm laser showed peaks at 638, 1112, 1608, and 3066 cm−1. Both offered proof that an epoxy was used as the impregnation material.

Figure 3. Peaks in the jadeite sample’s FTIR spectrum at 3061, 3037, 2965, 2925, and
2874 cm–1 proved that an epoxy was used as the impregnation material.
Impregnated jadeite jade appears to be readily separated from untreated material by DiamondView imaging. While more samples need to be examined, this technique could be a simple and effective way to identify impregnation treatment. Source: GIA @topic:13


Title: Dyed Purple Hydrophane Opal Abstract: Opals with an unusual purple bodycolor and strong play-of-color have recently appeared in the market. Reportedly from a new deposit in Mexico, they have a vivid bodycolor unlike that of any natural play-of-color opal seen in the trade so far. This alone was enough to raise suspicion, and gemological and spectroscopic evidence indicates that the purple coloration is artificial. A comparison of this purple opal with numerous samples from Ethiopia’s Wollo Province strongly suggests that it is actually dyed hydrophane opal from those deposits. Several previously undocumented characteristics of Wollo opals are described, including zeolite mineral inclusions. Source: GIA @topic:12


Title: Update on Mexifire Synthetic Fire Opal Abstract: As a result of changes in the manufacturing process, recent production of the synthetic fire opal marketed as “Mexifire” exhibits some new properties. While the earlier material could be identified on the basis of low RI and SG values, the new synthetics have values that are quite similar to—and partially overlap those of—natural fire opals. With the change in the manufacturing process, the water content has also changed, as reflected in the IR spectra. Source: GIA @topic:12


Title: Inclusions in Aquamarine from Ambatofotsikely, Madagascar Abstract: In January 2012, aquamarine crystals containing interesting inclusions were extracted from the Ambatofotsikely area northwest of Antsirabe, Madagascar. These specimens displayed various types of eye-visible and microscopic inclusions, and some had an unusual form. Raman microspectroscopy identified reddish brown platelets as hematite, while ilmenite was found as black platelets, black needles, and distinctive dark gray dendrites. Similar inclusions are known in beryl from Brazil, India, Mozambique, and Sri Lanka. Source: GIA @topic:3


Title: Update on "Low-Temperature" Heat Treatment of Mozambican Ruby: A Focus on Inclusions and FTIR Spectroscopy Abstract: High-temperature heat treatment has long been the most widely used method for improving the color of corundum. Soon after Mozambique emerged as an important source of rubies in 2009, it was discovered that these stones reacted well to a lower-temperature heating process.

GIA's Bangkok laboratory recently performed heat treatment experiments on 47 Mozambican rubies mined in Mugloto (Montepuez area) and observed the changes that occurred after known conditions of temperature and duration. The results are available in a new study titled "Update on ‘Low-Temperature’ Heat Treatment of Mozambican Ruby: A Focus on Inclusions and FTIR Spectroscopy.”

The experiments showed that the blue component could be reduced at fairly low temperatures and improve the color to a purer red (changing from purplish red to red). While heat treatment is difficult to detect in Mozambican rubies, a combination of inclusion study and FTIR spectral analysis gave consistent and accurate results. Source: GIA @topic:3


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. Source: GIA @topic:2


Title: 18th Annual Sinkankas Symposium Abstract: A 32.35 mm alexandrite twinned crystal and a 2.61 ct faceted alexandrite, both from Russia, shown in daylight (left) and incandescent light (right). Photos by Robert Weldon; courtesy of William Larson.
The 2022 Sinkankas Symposium, an annual event featuring presentations by specialists in gem-related disciplines, will follow a virtual format once again this year with pre-recorded sessions available on-demand. Sponsored by the Gemological Society of San Diego, the Geo-Literary Society, and GIA, the symposium will include 10 pre-recorded 30-minute presentations available to view from April 25 through June 6, highlighting alexandrite and other color-change gemstones (see above).
Speakers will include Evan Caplan, William Larson, Cigdem Lüle, Sally Eaton-Magaña, Niveet Nagpal, Nathan Renfro, Stuart Robertson, Aaron Palke, George Rossman, Wim Vertriest, and Robert Weldon. The presentations will cover a variety of topics regarding alexandrite and other color-change gemstones, from characteristics and sources to market trends and photography.
Registration closes June 1. The registration cost of $25 includes a PDF of the symposium volume, available June 23. Visit https://sinkankassymposium.net for more details. Source: GIA @topic:3


Title: “Floating Flower” Inclusions in Aventurine Quartz Bangle Abstract: Figure 1. Bangles of similar appearance fashioned from different materials: jadeite jade (left), albite (center), and aventurine quartz (right, client sample). All exhibit green “floating flower” inclusions. Photos by Lai Tai-An Gem Lab.
While gemologists use data to identify a gem, consumers can only judge the identity of an object by its appearance, which may lead to differences of opinion in the market. The identification of the material is not difficult for labs, but the present case is a good example of the misunderstandings that can happen outside of a gem lab. A recent submission highlighted this situation. A difference of opinion between a seller and buyer over the identity of a bangle resulted from the appearance created by “floating flower” features (akin to falling blossoms) visible with the unaided eye. One party believed the features were more consistent with icy jadeite jade, while the other thought they were more in keeping with albite. Analysis in our laboratory proved neither was correct.

Figure 2. FTIR (top) and Raman (bottom) spectroscopy confirmed the client’s bangle was
fashioned from aventurine quartz. Peaks observed in the FTIR spectra (main peaks at 1176,
1089, and 480 cm–1) and Raman spectra (main peak at 463 cm–1) did not match those expected
for albite or jadeite jade. FTIR and Raman spectra of aventurine quartz were collected from the
client’s sample; spectra of albite and jadeite jade were from the author’s database.
The object weighed approximately 37 g and measured 72 × 10 mm, and it appeared semitransparent to transparent with a white bodycolor incorporating light green to green inclusions (right photo in figure 1). A spot RI of around 1.54 was obtained, together with an SG of approximately 2.66. Both excluded jadeite jade as a candidate, but albite was still an option. Further examination by FTIR absorbance and Raman spectroscopy (785 nm laser) ruled out albite and confirmed the material was aventurine quartz (figure 2). Typically, aventurine quartz is not as transparent as the material from which the bangle was fashioned, and this contributed to the misidentification as “jadeite jade,” especially given the presence of the green “floating flower” inclusions.

Figure 3. Left: The disorderly, flaky green mineral inclusions were clearly visible in the bangle. Field of view 5.5 mm. Right: The green inclusions appeared red through a Chelsea filter when illuminated by strong daylight illumination. Photos by Lai Tai-An Gem Lab.
Further examination of the disorderly green mineral inclusions (figure 3, left) using a Chelsea filter revealed a distinct red color under strong daylight illumination—characteristic of fuchsite mica (figure 3, right).
In the past, clients have mistaken highly translucent albite containing “floating flower” inclusions as jadeite jade, and vice versa. This particular case proves that the same misidentification may apply to examples of highly translucent aventurine quartz containing inclusions often observed in jadeite jade and albite. Source: GIA @topic:13


Title: A Fantastic Display of Phase Changes in a Sapphire’s Fluid Inclusion Abstract: This negative crystal, measuring 1 mm in length, contains a large graphite crystal and carbon dioxide. When cooled below the supercritical point, the CO2 exists as a gas and liquid; gas bubble gaseous CO2 is visible due to the difference in refractive index between the liquid and gas phases (B–F). When heated above the supercritical point, the CO2 homogenizes into a supercritical fluid (A and G). The flat surface of the negative crystal gives rise to a high nucleation density of gas bubbles, which ultimately coalesce into a single large (B and E). Photomicrographs by Nathan Renfro.

	In corundum of metamorphic origin, the presence of carbon dioxide (CO2) fluid inclusions is a useful diagnostic indicator that no heat treatment has occurred; a gemologist simply has to cool the stone to below approximately 31.5°C to observe these inclusions (J.I. Koivula, “Carbon dioxide fluid inclusions as proof of natural-colored corundum,” Fall 1986 G&G, pp. 152–155). Even though this type of inclusion is considered commonplace in sapphires that form in a metamorphic environment, a spectacular example was recently witnessed in a Sri Lankan sapphire.

	Sapphire's Fluid Inclusion

	Temperature and pressure conditions create phase changes in this Sri Lankan sapphire's negative crystal inclusion.

	When viewed correctly, the inclusion is revealed to be a negative crystal with a very tabular morphology (figure 1); for more on distinguishing negative crystals, see Fall 2009 Lab Notes, pp. 212–213. The negative crystal also contains a rather large graphite crystal. As the specimen’s temperature is lowered, the CO2 trapped in the negative crystal remains homogenized with no bubbles present until reaching approximately 31.5°C, whereupon both liquid and gas phases become clearly observable. The homogenized state represents a supercritical fluid, one that behaves like a liquid and a gas under certain conditions. Under these circumstances, the CO2 assumes the shape of its “container” (the negative crystal) and can be compressed much like a gas phase while retaining the density of a liquid. This supercritical phase of CO2 has some unique properties, such as the ability to dissolve certain substances, which is otherwise impossible in its gas or liquid phase. The observation of the phase change elegantly illustrates the temperature and pressure conditions of this fluid inclusion system. Such inclusions generate pressure 75 times that of sea level (>1000 psi), and this extreme pressure accounts for their tendency to rupture during heat treatment (see E. Roedder, Fluid Inclusions, Reviews in Mineralogy, Vol. 12, Mineralogical Society of America, Washington, DC, 1984).

	When CO2 is cooled below 31.5°C, the liquid and gas phases have very different densities and thus very different refractive indices, making them clearly distinguishable. Above that temperature, while in the supercritical state, the homogenized liquid has a uniform density, and the two phases are impossible to differentiate. As one raises and lowers the temperature, the changing internal scene repeatedly follows this fascinating course.

	In this example of a CO2-filled negative crystal, numerous bubbles spontaneously nucleate as the temperature drops below the supercritical point. This proliferation is largely due to the flat, smooth surfaces of the tabular void. The highest-energy areas for the bubbles to nucleate exist on minute imperfections along these flat surfaces, creating an extraordinarily high nucleation density of gas bubbles. This is one of the most fantastic examples of a carbon dioxide fluid inclusion phenomenon the authors have encountered in sapphire. Source: GIA @topic:3


Title: Prismatic Rutile in Quartz Abstract: Figure 1. Left: Depending on the viewing angle, these two rutile crystals in rock crystal quartz seem to be touching each other. In the foreground is a black-silver prismatic crystal, and below on the right is a shadowed, fragmented piece, seen in diffuse/fiber-optic illumination. Right: The use of Rheinberg illumination gives warmer colors to the rutile crystals and the background. Photomicrographs by Jonathan Muyal; field of view 14.52 mm.
Rutile, a mineral composed mainly of titanium dioxide (TiO₂), is a common inclusion in quartz in the form of profuse acicular hair-like crystals (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 1, ABC Edition, Zurich, 1986). These golden needle inclusions are appreciated as a pleasing feature, giving their name to the variety known as rutilated quartz.
However, prismatic single rutile crystal inclusions in quartz remain an underappreciated feature, often synonymous with “flaws.” They are rarely showcased by the lapidary. Nevertheless, we observed a 21.27 ct cushion-cut rock crystal quartz that displayed a large, well-formed rutile crystal inclusion (see above) under the table.
The protogenetic inclusion showed a black-silver color with adamantine to submetallic luster, a well-formed tetragonal (“stubby”/blocky) prismatic crystal habit with fine striation along its length (parallel to the c-axis), and smooth pyramidal termination faces. Cyclical twinning such as twin knee/sharply angled twins on [011] and parallel twinning crystal growth along the length were also observed (again, see above).
Very close below, in the background, was another rutile crystal inclusion, this one a fragmented piece. At first glance, it could be mistaken for part of the main crystal inclusion described above. Nevertheless, this rutile fragment adds details to the overall visual composition.
Rheinberg illumination (Fall 2015 Micro-World, pp. 328–329) using blue and yellow filters provided additional contrast. Lighting technique is critical in photomicrography. Here it dramatically enhanced the inclusion scene, offering alternative vibrant colors for aesthetic purposes.
This rock crystal quartz had preserved and beautifully highlighted a prismatic rutile crystal inclusion, like a collector mineral specimen in a display window. Such a large inclusion specimen also provides valuable mineralogical information for the gemologist. Source: GIA @topic:3


Title: “Boomerang” Inclusion in a Rough Topaz Abstract: The “boomerang” inclusion in this topaz was confirmed by Raman spectroscopy to be a twinned crystal of tantalite-(Mn). Photomicrograph by Shu-Hong Lin; field of view 0.71 mm.
A 21.46 ct colorless rough topaz was recently submitted to Taiwan Union Lab of Gem Research (TULAB) for identification service. Microscopic observation showed a few prismatic brown inclusions with submetallic luster. One of the inclusions was a unique twinned crystal composed of two prismatic crystals forming a 120° intersection angle. With its shape and backdrop, the twinned crystal resembled a boomerang flying across the sky (see above). This inclusion was later confirmed to be tantalite-(Mn), based on Raman spectroscopy and comparison with the RRUFF database. Polarized light and reflected illumination were adopted to reduce doubling and obtain clearer photomicrographs, and the images were processed to extend depth of field. Source: GIA @topic:2


Title: Six-Rayed Star in Sapphire from Myanmar Abstract: This inclusion scene features an apparent iron sulfide crystal against a midnight blue backdrop. It is reminiscent of the night sky, echoing the surface appearance of the star sapphire host. Photomicrograph by E. Billie Hughes; field of view 2.15 mm.

Gems are renowned for their outward beauty, but their internal world can be just as striking. Lotus Gemology recently came across a Burmese sapphire, cut as a cabochon and measuring 8.92 × 7.10 × 4.75 mm, that displayed a six-rayed star. Once we examined it under the microscope, we were surprised to find that this celestial theme carried through to the inclusion scene inside (see above).

The long, undissolved rutile silk needles that form the six-rayed star are evident in angular zones. We could also see other inclusions typical of unheated sapphire, such as the tiny negative crystals forming a “fingerprint” at the top of the image. What was most interesting about this piece was the large, irregularly shaped crystal with a metallic appearance hovering close to the surface of the cabochon dome, which we believe is an iron sulfide crystal based on its appearance. This highly reflective crystal seems to float across a midnight blue backdrop, reminiscent of an asteroid floating in space and making for a fitting inclusion in a star sapphire. Source: GIA @topic:3


Title: “Fishbone” Inclusion in a Burmese Peridot from Mogok Abstract: The fishbone-like inclusion in the Burmese peridot. Photomicrograph by Shu-Hong Lin; field of view 1.32 mm.
Recently, an 83.25 ct cushion faceted peridot with medium dark yellowish green color and good clarity was sent to the Taiwan Union Lab of Gem Research (TULAB) for identification service. This peridot, reported by the owner as from Mogok, Myanmar, was relatively rare in the Taiwanese market because of its impressive size, color, and clarity. Microscopic examination revealed a few short needle inclusions and a fishbone-shaped inclusion (see above), the latter of which is common in peridot from this origin. The backbone appeared to be a long prismatic crystal with some vertical cleavage planes along it, while the smaller branches were composed of parallel tabular inclusions that might result from epitaxial exsolution. Due to peridot’s strong birefringence, brightfield illumination and plane polarized light were adopted to reduce the interference and obtain clear microscopic images. Source: GIA @topic:1


Title: Trapiche Rhodochrosite Abstract: Figure 1. The trapiche-like rhodochrosite “flower” on the left, measuring 30 mm across and weighing 35 ct, is from Argentina’s Capillitas mine. This piece appears to be formed by the intersection of three crystals, with 60° of separation. The 56 ct rhodochrosite specimen on the right, also from the Capillitas mine, measures 40 mm across. Photos by Russell E. Behnke; from the author’s collection.

	It is not often that a very old locality produces a gem material previously unrecorded in the literature. Yet the Capillitas mine in Argentina’s Catamarca Province, once mined by the Incas and long known for its fine rhodochrosite stalactites, has yielded two trapiche-like rhodochrosite gemstones, first observed by the author in August 2014.

	The stalactite that produced these two slices was reportedly found in the 1980s. The smaller of the two specimens, a 30 mm round weighing 35 ct (figure 1, left), is a symmetrical example of this rhodochrosite’s cogwheel habit. The 40 mm oval, which weighs 56 ct (figure 1, right), was cut from the same stalactite; it is the only other example of this formation the author could locate.

	Rhodochrosite from the Capillitas mine typically consists of minute crystalline grains. These two examples, however, are very coarsely crystalline and are quite possibly twinned, which would explain both the unusually large size of these crystals and their obvious symmetry.

	Dr. Carl Francis, former curator of the Mineralogical Museum of Harvard University, points out that stalactites of calcite, which are chemically and structurally similar to rhodochrosite, rarely exhibit this type of growth (pers. comm., 2014). The floral pattern of these red gemstones makes them beautiful and incredibly rare. Source: GIA @topic:2


Title: Aurora Iris Agate Abstract: Figure 1. In transmitted light, this skillfully carved iris agate displays a scene reminiscent of an aurora. Photomicrograph by Nathan Renfro; field of view 5.28 mm.

	When solar wind interacts with the earth’s magnetosphere, spectacular multicolor light shows occur. This phenomenon is referred to as an aurora borealis in the Northern Hemisphere and an aurora australis in the Southern Hemisphere. This author recently examined an iris agate that provided a microscopic scene remarkably similar to an aurora (figure 1). The 1.67 ct carving seen in figure 2 was fashioned by Falk Burger (Hard Works, Tucson, Arizona). Burger took advantage of this quartz’s unique growth texture by carving the agate’s back, producing a wispy iridescent effect that is visible when using a point light source. Along the lower portion of the gem was a thin layer of crystalline quartz with a seam of pyrolusite dendrites between the crystalline quartz and microcrystalline iris agate. The combination of these layers gives the viewer the impression of an aurora occurring over a forest-rimmed frozen lake (see video at www.gia.edu/gems-gemology/aurora-iris-agate-carving).

	Figure 2. The 1.67 ct iris agate, shown here in transmitted light (left) and reflected light (right) was carved to showcase the dynamic nature of the iridescent colors. Photos by Kevin Schumacher. Source: GIA @topic:3


Title: Chrysoberyl Inclusions in Flux-Grown Ruby Abstract: Figure 1. This ruby proved to be a flux-grown synthetic ruby with chrysoberyl inclusions. Photo by Shunsuke Nagai.

The Tokyo laboratory recently received a 3.02 ct red pear-shaped mixed cut measuring 10.93 × 7.04 × 5.03 mm (figure 1). Standard gemological testing yielded a refractive index of 1.765–1.773; a hydrostatic specific gravity of 4.00; absorption lines at 693, 476, and 468 nm; and a broad absorption band between 500 nm and 610 nm seen using a handheld spectroscope. All of these properties were consistent with ruby. The stone displayed strong red fluorescence under both long-wave and short-wave UV.

Figure 2. These natural-looking hexagonal colorless crystals and the small nest of inclusions in the flux-grown ruby (top of image and around the hexagonal crystals) could be mistaken for natural corundum inclusions. Photomicrograph by Yuxiao Li; field of view 1.41 mm.
Microscopic examination revealed numerous hexagonal colorless inclusions as well as small colorless inclusions that resembled zircon nests often found in natural corundum (figure 2). Also observed were features suggesting the possibility of flux-grown corundum: hexagonal dark reflective long prisms and platelets (figure 3) and healed fissures filled with flux residues (figure 4).

Figure 3. The hexagonal dark reflective long prisms (left) and platelets (right) observed in the sample are common inclusions in flux-grown synthetic corundum. Photomicrographs by Yuxiao Li; field of view 1.28 mm.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) detected high amounts of Be (35.3–37.1 ppma), Cr (1733.5–2047.2 ppma), Rh (0.6–1.0 ppma), and Pt (0.5–1.1 ppma). Elements normally present in natural corundum such as Mg, Ga, and V were not detected. The chemistry indicated a flux growth process.

Figure 4. Fingerprints in the flux-grown ruby could also be mistaken for natural residue-filled fingerprints. Photomicrograph by Yuxiao Li; field of view 1.23 mm.
Earlier work has shown numerous transparent, colorless hexagonal tabular “ghost-like” inclusions in Chatham flux-grown sapphire (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 study, X-ray diffraction analysis (XRD) revealed that the pattern of the ghost-like inclusions was identical to that of chrysoberyl. That study also stated that Chatham, who was successful in synthesizing sapphire by the flux method, added heavy concentrations of beryllium, which explained the presence of chrysoberyl and the high beryllium trace element content. More recently, natural-looking transparent hexagonal crystals in a flux-grown pink sapphire have also been reported (Fall 2017 Lab Notes, pp. 367–368).

Figure 5. The Raman spectrum of the chrysoberyl inclusion compared to that of the known reference.
There was no surface-reaching transparent crystal in that pink synthetic sapphire, but the small amounts of beryllium suggested the possibility of chrysoberyl. In the present laboratory-grown ruby, fortunately, one of the transparent crystals reached the surface. With Raman spectroscopy, we were able to identify it as chrysoberyl (figure 5).
The beryllium concentration of this laboratory-grown ruby (up to 37 ppma) indicated possible beryllium diffusion treatment. High chromium (up to 2047 ppma) resulted in a vivid red color. With such a highly saturated bodycolor, we cannot deny the possibility of beryllium diffusion, though the signature orange rim was not found using immersion techniques. The numerous chrysoberyl crystals offer important evidence that the beryllium was already excised during the flux growth process. Beryllium diffusion of corundum requires exposure to extreme heat (above 1780°C; J.L. Emmett et al., “Beryllium diffusion of ruby and sapphire,” Summer 2003 G&G, pp. 84–135). These chrysoberyl inclusions do not show the typical indications following heat treatment, meaning this stone was not beryllium diffused after its growth.
With LA-ICP-MS and Raman spectroscopy, we were able to confirm that flux-grown laboratory-grown ruby with high beryllium content could indicate the presence of natural-looking chrysoberyl crystals. Source: GIA @topic:3


Title: A Remarkably Large Amblygonite-Montebrasite Carving Abstract: Figure 1. This 1,871 g amblygonite-montebrasite carving (18.50 × 15.10 × 7.30 cm) is unusual for its size and transparency. Photo by Gagan Choudhary.

Recently the Gem Testing Laboratory in Jaipur had an opportunity to examine an unusually large yellow, semitransparent to translucent carving (figure 1). This 1,871 g (9,355 ct) piece measuring approximately 18.50 × 15.10 × 7.30 cm was fashioned after Lord Mahavira, one of the ancient Indian sages who established the tenets of Jain Dharma. Initial observations suggested beryl due to the color, medium heft, and cloudy liquid inclusions visible to the unaided eye. Gemological testing ruled out that possibility, however. Spot RI was approximately 1.61, with a small but distinct birefringence blink, while hydrostatic specific gravity measured 3.00. The carving was inert to UV radiation.

Examination with a hand loupe revealed reflective liquid films (figure 2, left), fingerprints composed of phase droplets, elongated phase/short tubes oriented in one direction, aligned in planes intersecting at approximately 65/115° angles (figure 2, center). Also present were parallel reflective films that appeared to be incipient cleavage (figure 2, right). The overall inclusion pattern was typical of gems found in pegmatitic bodies such as beryl, tourmaline, and topaz.

Figure 2. Examination of the carving with a hand loupe revealed reflective liquid films (left), elongated phase/short tubes oriented in one direction and aligned in planes intersecting each other at approximately 65/115° (center), and parallel reflective films that appeared to be incipient cleavage (right). Photos by Gagan Choudhary; image width 25 mm.
The carving was identified as amblygonite-montebrasite by Raman spectroscopy in the 200–2000 cm–1 region, which revealed distinct peaks at ~297, 425, 481, 600, 643, 797, 1011, 1058, 1107, and 1186 cm–1 (figure 3). Amblygonite and montebrasite are both lithium phosphates with a common chemical formula of (Li, Na)AlPO4(F, OH), forming an isomorphous series between F-rich amblygonite and OH-rich montebrasite. The two minerals can be colorless, yellow, or green. High-quality crystals are prized by collectors but rarely seen in the gem trade (R. Webster, Gems: Their Sources, Descriptions and Identification, 5th ed., rev. by P.G. Read, Butterworth-Heinemann, Oxford, UK). The amblygonite and montebrasite end members can be differentiated on the basis of peaks at ~600 and 1060 cm–1 and a peak at ~3370 cm–1. With an increasing percentage of fluorine, the 600 cm–1 peak shifts from 599 to 604 cm–1 while the 1060 cm–1 peak shifts from 1056 to 1066 cm–1 (B. Rondeau et al, “A Raman investigation of the amblygonite-montebrasite series,” The Canadian Mineralogist, Vol. 44, No. 5, pp. 1109–1117). According to the RRUFF database, however, the peak for montebrasite is at 1047 cm–1 while amblygonite’s is at 1060 cm–1. This is possibly due to different instrument settings. Although the ~3370 cm–1 peak was not studied here, the 600 and 1058 cm–1 peaks in this carving suggested that it belongs to an intermediate state in the amblygonite-montebrasite series.

Figure 3. The carving’s Raman spectrum showed major peaks at around 297, 425, 481, 600, 643, 797, 1011, 1058, 1107, and 1186 cm–1. The peaks at approximately 600 and 1058 cm–1 suggest an intermediate member of the amblygonite-montebrasite series.
Amblygonite-montebrasite is known from many localities, especially the United States and Brazil, but the client did not know the source of the carving. A few faceted samples have been examined at this laboratory, but the carving documented here was exceptional for its large size and transparency, despite its brittleness and tendency to crack. Source: GIA @topic:1


Title: Quarterly Crystal: Heavily Etched Blue Beryl Crystals Reportedly from Pakistan Abstract: Figure 1. Three blue beryl crystals showing the heavily etched and corroded appearance typical of this material. The largest crystal is 236.8 g, while the other two weigh 16.1 g (left) and 13.8 g (right). Photo by Diego Sanchez.
In previous Micro-World columns, the Quarterly Crystal entry has showcased exceptional crystalline specimens masterfully crafted by geological forces. In some cases, however, it is the darker destructive forces of nature that produce a fine mineral specimen. In 2018, Raza Shah (Gems Parlor, Fremont, California) began unearthing heavily etched dark blue beryl crystals from Khyber Pakhtunkhwa in northern Pakistan. Bryan Lichtenstein (3090 Gems, San Francisco, California) submitted three of these crystals to GIA’s Carlsbad lab for identification services (figure 1; see also B.M. Laurs and G.R. Rossman, “Dark blue beryl from Pakistan,” Journal of Gemmology, Vol. 36, No. 7, 2019, pp. 583–584).

Figure 2. The use of differential interference contrast imaging illustrates the complex growth and subsequent etching processes that lent the beryl crystals their unique appearance. These views are essentially parallel to the c-axis (left) and perpendicular to the c-axis (right). The left image shows terraced, stepped patterns created during crystal growth that are crosscut by oriented, elongate etch pits. Photomicrographs by Aaron Palke; field of view 2.88 mm.
The hexagonal barrel shape that must have characterized the crystals in their initial state is still apparent despite the heavy etching. The geological conditions responsible for beryl growth apparently persisted long enough for many of these crystals to grow to extreme sizes; the largest recovered so far weighs 236.8 g. At some point, these crystals appear to have fallen out of equilibrium with their natural environment and the beryl started dissolving back into the earth. Microscopic observation of the corroded surfaces shows how the dissolution process is controlled by the beryl crystal structure, with dissolution pits and the skeletal remnants of the beryl constrained by the underlying crystal lattice. Differential interference contrast (DIC) microscopy can be used to highlight both growth and dissolution features in the same image (figure 2). While Pakistan is an important source of aquamarine crystals and gems, this heavily etched dark blue aquamarine is truly a unique find. Source: GIA @topic:3


Title: Calcareous Coral and Epoxy Composite Abstract: Figure 1. The carved bangle submitted as “red calcareous coral.” Photo by Shu-Hong Lin.

Red calcareous coral is very popular in the Taiwanese market and has become far more expensive over the decades due to limited production and increasing demand. Red calcareous coral is usually cut into polished branches, beads, carvings, or cabochons. Recently, a bangle was submitted as calcareous coral to Taiwan Union Lab of Gem Research (TULAB) for identification service. It had a typical coral-red color (figure 1), though it was unusual to see a carved bangle due to the sizes of natural coral specimens that are found.

Figure 2. Short-wave ultraviolet fluorescence of the bangle presented a pattern of separate patches fluorescing white to orange. Photo by Kai-Yun Huang.
Standard gemological testing revealed that the refractive indices of this bangle were consistent with calcareous coral, at 1.48–1.65. However, its specific gravity of 2.27 was less than that of calcareous coral (2.6–2.7). Moreover, the short-wave ultraviolet fluorescence of this bangle presented a unique pattern of patches with chalky white to orange fluorescence next to each other (figure 2). Microscopic observations indicated that the patch-like fluorescence seemed to correspond to fragments of red calcareous coral, while the fragments were bonded with red material in which few bubble inclusions were found (figure 3).

Figure 3. The microscopic image of the carved bangle indicated that the fluorescing patches seemed to be fragments of red calcareous coral, while the gaps between the fragments were filled with red foreign material with few bubble inclusions. Photomicrograph by Yu-Shan Chou; field of view 5.46 mm.

Figure 4. The Raman spectra of the bangle matched those reported in the literature for red calcareous coral and epoxy resin, which meant the bangle was composed of fragments of red calcareous coral (A: Raman peaks at 704, 1087, 1128, and 1515 cm–1) and epoxy filling (B: Raman peaks at 638, 822, 1112, 1183, and 1606 cm–1). The stacked spectra are baseline-corrected and normalized.
To further confirm the identity of this bangle, the patches and the bonding material in between them were analyzed by Raman spectroscopy, and the resulting spectra were then compared with those of epoxy and red calcareous coral reported in the literature (figure 4; see K.E. Chike et al., “Raman and near-infrared studies of an epoxy resin,” Applied Spectroscopy, Vol. 47, No. 10, 1993, pp. 1631–1635; S. Karampelas et al., “Identification of the endangered pink-to-red Stylaster corals by Raman spectroscopy,” Spring 2009 G&G, pp. 48–52). The results showed that the fluorescing patches were natural calcareous coral, while the bonding material in between was epoxy resin.
This kind of composite product was likely made by bonding the stacked coral fragments with red epoxy resin to form a bulk material, which was then processed into carvings, cabochons, or even bangles. Although the coral-epoxy composite product looked similar to natural calcareous coral, it could be accurately distinguished through specific gravity, ultraviolet fluorescence reaction, microscopic observation, and Raman spectroscopy. Source: GIA @topic:14


Title: Book Review: Towards an Art History of Medieval Rings: A Private Collection Abstract: By Sandra Hindman, with Ilaria Fatone and Angelique Laurent-di Mantova. Introduction by Diana Scarisbrick, hardcover, illus., 260 pp., publ. by Paul Holberton Publishing, London, 2015, £35.00.

	The 35 rings in this private collection belong to Sandra Hindman, owner of Les Enluminures, a gallery of artworks from the Middle Ages and the Renaissance with locations in Paris, Chicago, and New York. The book is the accompanying catalog to recent exhibitions at Les Enluminures.

	It is one of the few modern volumes on the topic of medieval rings. Beautifully printed and illustrated, it is a scholarly overview of the design and use of medieval rings ranging from the Early Byzantine period through the Renaissance.

	The book is divided into individual chapters: Byzantine & Early Christian, Early Medieval, Gothic, and Renaissance. Each chapter gives a brief overview of the period and the drivers that influenced the creation of these rarities. The contents have been arranged chronologically so as to compare and contrast the styles between and within each period. In addition to multiple images of each ring, there are comparative photos of rings and objects in other collections. The book also presents the catalogue entry for each of the rings, featuring their description and technical details on construction and condition.

Towards an Art History of Medieval Rings is an exceptionally crafted and well-organized book for anyone interested in this rare topic. Source: GIA @topic:6


Title: Color Origin of Lavender Jadeite: An Alternative Approach Abstract: The market value of jadeite has risen dramatically in recent decades, often rivaling that of fine ruby and sapphire. Understanding the color origin of jadeite and reliably determining treatments have become increasingly important in the trade. This study uses single-crystalline analogs in conjunction with polycrystalline jadeite to examine the color origin of lavender jadeite through quantitative spectroscopy and modern trace-element analytical techniques. Several previously proposed chromophores are assessed for their possible contribution to jadeite coloration. Quantitative analysis confirms that green and lavender colorations are caused by chromium and manganese, respectively. The relative significance of these two chromophores is compared to determine their impact on observable coloration. The findings on color origin are applied to the identification of treated material on the current market. Source: GIA @topic:13


Title: Coloring of Topaz by Coating and Diffusion Processes: An X-Ray Photoemission Study of What Happens Beneath the Surface Abstract: Surface-treated topaz has become a viable alternative to topaz colored by irradiation.
Unlike irradiation, which modifies the entire gemstone, coloration by chemical modification is limited to the near-surface region. The treatment techniques are well established, but less is known about how the processes involved create the desired appearance. In this study, X-ray photoemission spectroscopy in combination with sputter depth profiling proved successful in characterizing two fundamentally different coloration mechanisms of chemically treated topaz: colored coatings and diffusion-induced coloration. Source: GIA @topic:1


Title: Tsavorite and Other Grossulars from Itrafo, Madagascar Abstract: Since 2002, tsavorite and other grossular varieties have been recovered from a primary deposit at Itrafo, a village in the Andrembesoa area of central Madagascar. Twenty-two samples from this locality were investigated by classical gemological methods, chemical analysis, and UV-Vis-NIR and mid-IR spectroscopy. The garnets’ chemical composition was nearly pure grossular (92 mol. %), with iron and vanadium as the main chromophores. Their iron content and Fe2O3:V2O3 ratio were higher than those generally found in tsavorite from well-known deposits. Although the Itrafo deposit is relatively large, and new veins could be discovered, future production will be limited by access difficulties and security concerns. Source: GIA @topic:2


Title: Aquamarine from the Thuong Xuan District, Thanh Hoa Province, Vietnam Abstract: Vietnamese aquamarine is notable for its attractive color and well-formed crystals. Commercially significant deposits are known only from the Thuong Xuan District in Thanh Hoa Province, where the aquamarine (as well as topaz) have been mined from granitic pegmatites and associated eluvial deposits. Rough and cut samples were investigated by standard gemological methods, Raman and IR spectroscopy, and electron microprobe and LA-ICP-MS chemical analysis. The samples were characterized by a low concentration of alkalis and relatively high amounts of iron and cesium. Raman and IR spectroscopy showed the presence of CO2 and type I H2O in the beryl structural channels. Source: GIA @topic:3


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

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

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

Table 1: Chemical composition of pyrope-spessartine garnet.

Samples
Wafer 1
Wafer 2
Wafer 3

Path length
3.553 mm
3.138 mm
3.284 mm

Carat weight
2.851 ct
3.706 ct
3.908 ct

Oxide wt.% (1)

CaO
8.46%
7.49%
5.98%

MgO
5.88%
8.25%
7.35%

MnO
25.11%
18.04%
22.73%

FeO
1.53%
3.34%
1.61%

Al2O3
21.72%
22.71%
22.39%

V2O3
0.23%
0.13%
0.24%

Cr2O3
0.06%
0.04%
0.08%

SiO2
36.66%
39.77%
39.11%

TiO2
0.28%
0.13%
0.18%

Total
99.93%
99.90%
99.67%

Cations (2)

Ca
0.7117
0.6074
0.4904

Mg
0.6881
0.9305
0.8387

Mn
1.6688
1.1560
1.4746

Fe2+
0.1003
0.2116
0.1032

Total dodec.
3.1689
2.9055
2.9070

Al
2.0085
2.0248
2.0209

V
0.0146
0.0078
0.0146

Cr
0.0038
0.0023
0.0048

Total oct.
2.0269
2.0348
2.0403

Si
2.8760
3.0094
2.9950

Ti
0.0164
0.0075
0.0102

Total tet.
2.8924
3.0169
3.0052

End member mol.%

Goldmanite
0.72%
0.38%
0.72%

Uvarovite
0.19%
0.11%
0.24%

Spessartine
52.66%
39.79%
50.73%

Pyrope
21.71%
32.03%
28.85%

Almandine
3.17%
7.28%
3.55%

Grossular
21.55%
20.41%
15.92%

Total
100.00%
100.00%
100.00%

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

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

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

CIE A illumination
CIE D65 illumination

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

70.10
6.67
26.35
69.17
-5.26
29.38

R
G
B
R
G
B

199.81
165.74
123.90
178.67
170.09
115.32

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

74.34
9.98
23.73
72.95
1.23
24.59

R
G
B
R
G
B

216.09
175.18
139.86
197.89
176.80
134.24

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

69.96
6.90
20.65
69.24
-4.94
23.80

R
G
B
R
G
B

196.99
165.53
134.00
176.48
170.38
125.84

Colorimetric Parameters of Three Garnet Wafers in The CIELAB 1976 Color Circle Source: GIA @topic:3


Title: Steam-Dyed Amber Abstract: Figure 1. Left: This “chicken-fat yellow beeswax” amber bead, approximately 15 mm in diameter, was treated by the steam dyeing method. Right: The unusually dark orange color of these pear-shaped samples comes from steam dyeing. Photos by Fen Liu.

	“Beeswax” amber, a common trade name used in the Chinese gem market, refers to yellow amber that has a semitranslucent, opalescent, milky appearance with greasy luster. Among the beeswax ambers, “chicken-fat yellow beeswax” is very popular for its bright color. Global production is limited, and the material is in high demand in the Chinese amber market. Therefore, many methods to enhance the color of beeswax amber have been attempted. In March 2016, the Guangzhou laboratory of the Gem Testing Center, China University of Geosciences (Wuhan) received four pieces of chicken-fat yellow beeswax amber samples from two different clients (figure 1); two more pieces were received in May from an unrelated owner (figure 2).

Figure 2. The two bright yellow beads in the center, 8 mm and 9 mm in diameter, were treated by steam dyeing, while the bracelet contains natural-color amber. Photo by Jiewan Huang.

	Infrared spectroscopy showed all ambers with typical “Baltic shoulder” patterns in the 1100–1300 cm–1 range, with low and broad bands in higher frequencies and a high, sharp peak at 1160 cm–1. Instead of the whitish yellow of natural Baltic ambers, we saw either bright yellow or orange hues, both of which are unusual. Under strong transmitted light, the yellow color of the round bead in figure 1 (left) showed a mottled distribution, which was proof of uneven dyeing (figure 3); however, microscopic examination revealed small squashed bubbles caused by “steam treatment.” Further, red color filaments unrelated to the cracks among the bubbles near the surface were traces of residual dyes (figure 4, left).

Figure 3. The darker mottled color patches in this sample indicate that the bead was unevenly dyed. Photo by Fen Liu.

	Figure 4. Left: The squashed bubbles are induced by steam treatment, and the red filaments are possible traces of residual dye. Photomicrograph by Fen Liu; field of view 2.95 mm. Right: The dark orange color zone among the bubbles, unrelated to the cracks, indicates that the color zone was introduced by dyeing. Photomicrograph by Shufang Nie; field of view 2.95 mm.

	The color of the pear-shaped samples appeared to be darker than the yellow associated with chicken-fat amber (again, see figure 1, right). This darker color faded slightly when the surface was swabbed with alcohol. Under 40× magnification, the bubbles appear to have yellow meniscuses. The bubble-rich regions were darker than the portions with fewer bubbles. In some areas among the bubbles, an abnormal dark orange color zone appeared to be induced by residual color matter (figure 4, right). All these observations indicated the amber pieces underwent some artificial treatment. The clients admitted that these beeswax ambers were treated by a new treatment method, called “steam dyeing,” which delivers gas bubbles from colored water into the amber structure at pressure and temperature conditions close to those of saturated water vapors.

	Steam dyeing treatment is easy to miss. The rapid development in amber treatment methods means that consumers and laboratories must be cautious when dealing with these “chicken-fat yellow beeswax” ambers. Source: GIA @topic:13


Title: Update on the Green Dragon Demantoid Mine in Namibia Abstract: Figure 1. Namibian demantoid retrieved from the Green Dragon mine and preserved in its host rock. Photo by Albert Salvato.
According to Stephan Reif, Namibia’s Green Dragon mine is the largest continuously operating demantoid deposit. Green Dragon has a complete mine-to-market approach, handling everything from mining, ore processing, sorting, cutting, and grading to wholesale. They mainly supply the European market through Vienna and the Asian market through Hong Kong.

The mine was discovered in a remote part of southern Namibia in the 1990s and has been producing since the mid-2000s. In 2017, Green Dragon received a 25-year mining license for the deposit, offering stability as an incentive to invest in the mine. In the near future, mining will be scaled up and production will increase. This will provide a more consistent and attractive supply for buyers in the trade. As part of the 25-year mining lease, Green Dragon has committed to supporting the local communities.

Operations at the Green Dragon Mine
Stephan Reif provides an update on the activities at southern Namibia’s Green Dragon demantoid mine.
Namibian demantoid mining is highly mechanized, using heavy equipment to extract the green garnets from their host rock (see figure 1). Monthly production varies between 15 and 20 kg. Of that, a little over 10% is considered gem quality and goes for faceting.

Color ranges from yellowish green to bluish green, and some darker brownish greens are also found. Demand for certain colors varies, but at the moment the yellowish “golden” colors are in highest demand by designers. For Reif, the ideal Namibian demantoid is a slightly bluish green gem full of fire and brilliance.

Figure 2. The cutting and polishing of Namibian demantoid should emphasize the material’s lighter color and high dispersion. Photo by Albert Salvato.
The combination of lighter color and very high dispersion sets Namibian demantoid apart from other green garnets. These properties also depend on the quality of cutting and polishing (figure 2), something Green Dragon has focused on in recent years by having their in-house lapidaries and quality control perform to a higher standard. Because clarity, color, and calibration standards are so tight, the yield is only around 9%.

Most of the production is in melee and small calibrated sizes, with fine singles being extremely rare. Fine-quality melee is in very high demand in Europe at the moment, especially in the 4.0–6.5 mm range. In recent years, the demand for very small melee (1–2 mm) has increased substantially. Larger exceptional pieces typically go to Asia. Source: GIA @topic:2


Title: Uranium Contents of Hyalite Abstract: Figure 1. Two different types of Japanese hyalite rough specimens under daylight (left) and short-wave UV light (right). The photo on the right demonstrates the strong yellow-green fluorescence of pegmatite hyalite, while the spherical hyalite samples do not show the fluorescence. Photo by Masumi Saito.

Hyalite is a colorless variety of common opal with strong greenish fluorescence. Rough specimens have interesting glassy botryoidal shapes formed by vapor transport in volcanic or pegmatitic environments (O.W. Flörke, “Transport and deposition of SiO2 with H2O under supercritical conditions,” Kristall und Technik, Vol. 7, 1972, pp. 159–166). Hyalite from a new source in Zacatecas, Mexico, discovered in 2013, shows strong green fluorescence even under daylight conditions. This material was spotlighted for the first time at the 2014 Tucson gem and mineral shows (E. Fritsch et al., “Green-luminescing hyalite opal from Zacatecas, Mexico,” Journal of Gemmology, Vol. 34, 2015, pp. 490–508).

GIA’s Tokyo laboratory recently had an opportunity to examine several faceted hyalites from Zacatecas, Mexico, along with several rough hyalites from other locations, including Japan, Hungary, and Argentina. There were two different types of Japanese hyalites in the study samples: botryoidal and spherical. The botryoidal one (figure 1) was from Gifu’s Naegi granitic pegmatite (H. Ogawa et al., “Fluorescence of hyalite in pegmatite from Naegi granite, Nakatugawa,” 2008 Annual Meeting of Japan Association of Mineralogical Sciences), while the spherical one was from Toyama’s Shin-yu hot spring (Y. Takahashi et al., “On the occurrence of opal at the Shin-yu hot spring, Tateyama,” Tateyama Caldera Research, Vol. 8, 2007, pp. 1–4.). Hungarian hyalite is known to form in the clefts of trachytic rocks in Bohemia, Czech Republic, and Auvergne, France (B. von Cotta, Rocks Classified and Described: A Treatise on Lithology, Longmans, Green, and Company, London, 1866, p. 425). Argentinean hyalite is widely distributed, but the original rocks are not described.

Standard gemological testing of the faceted Mexican stones revealed RI values of 1.460–1.461 and a hydrostatic SG of 2.13. Prominent fluorescence was observed under short-wave UV light, but only the Japanese spherical samples were inert (figure 2). Strong graining flow structures were visible at 64× magnification. Raman analysis (figure 3) revealed typical amorphous silica spectra composed of a major band between 430 and 460 cm–1 (vibration of bridging oxygen) and a band centered at 790 cm–1 representing the stretching of isolated SiO44– (P. McMillan, “A Raman spectroscopic study of glasses in the system CaO-MgO-SiO2,” American Mineralogist, Vol. 69, 1984, pp. 645–659). Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) detected a very wide range of uranium contents; the maximum was 1060–1330 ppmw for the Japanese pegmatitic hyalite, while the Japanese spherical hyalite had zero uranium content. The amounts are quite inhomogeneous, but seem to correlate with the intensities of fluorescence, decreasing from Mexican (1180–3.55 ppmw) to Argentinian (2.48–2.49 ppmw) to Hungarian (0.39–0.15 ppmw) (figure 3).

Figure 2. Clockwise from top center, one Hungarian botryoidal hyalite with matrix, one Japanese pegmatite rough hyalite with matrix, twenty-three pieces of Japanese spherical hyalite, one rough and three faceted Mexican specimens, and one Argentinian botryoidal hyalite under short-wave UV light. The intensity of yellow-green fluorescence vary in the different specimens. Photo by Masumi Saito.

Figure 3. Raman spectra from (a–b) Mexican hyalites, (c) Japanese pegmatitic hyalite,
(d) Hungarian hyalite, (e) Argentinean hyalite, and (f–g) Japanese spherical hyalite. All
spectra show similar patterns, with the Mexican specimens showing the unknown specific
peak at 1548 cm–1.
Interestingly, only the Japanese pegmatitic hyalite sample was rich in rare earth elements (REE). Since Naegi granitic pegmatite is known to be an REE-enriched pegmatite (T.S. Ercit, “REE-enriched granitic pegmatites,” in R.L. Linnen and I.M. Samson, Eds., Rare-Element Geochemistry and Mineral Deposits, Geological Association of Canada, GAC Short Course Notes 17, 2005, pp. 175–199), the host rock chemistry appears to affect the silica-rich fluid. Source: GIA @topic:12


Title: Pink and Red Epidote in Quartz Abstract: Figure 1. Bright pink to red epidote crystals as “firework” sprays were a surprising discovery in rock crystal quartz. Photomicrograph by Nathan Renfro; field of view 2.16 mm.
We recently discovered very photogenic clusters of hot pink to red crystals as “firework” sprays (figure 1) in two transparent cabochons of rock crystal quartz. The cabochons weighed 5.47 ct and 11.18 ct and measured 15.85 × 9.87 × 5.92 mm and 16.06 × 11.49 × 7.83 mm, respectively (figure 2). These cabochons, which came from Sara Crystal in Shanghai, are thought to be from Chenzhou in China’s Hunan Province.

Figure 2. Weighing 11.18 ct (left) and 5.47 ct (right), these two rock crystal quartz cabochons play host to very unusual pink crystal sprays. Photo by Adriana Robinson.
After performing gemological testing and optical microscopy, we thought the inclusions might be piemontite based on their behavior in polarized light and the monoclinic morphology of the individual terminated crystals. Because some of the pink crystals reached the surface of their polished hosts, we decided to analyze them using Raman microanalysis. The result was a close match for epidote, which was surprising since epidote is normally thought of as a dark brownish green mineral.
The results of chemical analysis using laser ablation–inductively coupled plasma–mass spectrometry were consistent with epidote, but with one additional element present: manganese, which caused the pink to red color in these microcrystals. We concluded that the inclusions were indeed epidote instead of piemontite, but pink to red epidote was something completely new to us.
Searching the literature for piemontite and epidote uncovered the following statement from Mindat.org, which seemed to explain the existence of these pink to red epidotes:
“Piemontite” has two different uses: Piemontite (sensu stricto) is the mineral species described here, but more commonly “piemontite” refers incorrectly to deep red colored, -bearing epidotes that are really varieties of the species epidote, and not strictly speaking piemontite. “Piemontites” rarely contain more than 40% of the piemontite molecule, so many “piemontites” in collections (and pictured here in Mindat) are really Mn-rich red varieties of epidote.
To our knowledge, this pink to red epidote-quartz inclusion-host association has not previously been reported. Source: GIA @topic:2