Title: Man-Made “Inclusion”? Abstract: Figure 1. Fiber inside a cavity filled with liquid resin in a cushion-cut emerald measuring 8.2 × 7.3 × 3.1 mm. Photomicrograph by Holman Alvarado.
Two important internal features in gemstones are inclusions and fissures. Inclusions are an important source of information in the gemological evaluation process. They can often provide indications about geographic origin (see, e.g., S. Saeseaw et al., “Three-phase inclusions in emerald and their impact on origin determination,” Summer 2014 G&G, pp. 114–132); growth conditions (e.g., A. Cheilletz et al., “Time-pressure and temperature constraints on the formation of Colombian emeralds: An 40Ar/39Ar laser microprobe and fluid inclusion study,” Economic Geology, Vol. 89, No. 2, 1994, pp. 361–380; J.G. Toloza et al., “Similarities and differences between fluid inclusions hosted by Colombian emeralds,” Special Issue on the 15th IAGOD Symposium, 2018, pp. 166–167); natural or synthetic origin (e.g., N.D. Renfro et al., “Chart: Inclusions in natural, synthetic, and treated emerald,” Winter 2016 G&G, pp. 402–403); and whether the stone has been treated to improve clarity.
Fissures are openings in the stones, and those “empty” spaces affect clarity in a negative way. Therefore, gemstones are treated to fill those gaps with different substances. Fillers can generate physical phenomena that resemble natural inclusions and may be misleading to the untrained eye.
Emeralds are most commonly enhanced with fissure filling. Fillers in emerald are identified by looking at the flash of color (blue, violet, orange, and yellowish) shown when the transmitted light of the microscope hits the inclusions or with the use of FTIR or Raman spectroscopy.

Figure 2. Fiber seen inside the cavity under 365 nm UV light at 50× magnification. Photomicrograph by Luis Gabriel Angarita.
Recently the authors identified a man-made “inclusion” in a 1.15 ct cushion-cut Colombian emerald (figure 1) measuring 8.2 × 7.3 × 3.1 mm. It displayed a typical yellow flash most commonly seen in emeralds filled with liquid resin, which was later corroborated by FTIR spectroscopy. The “inclusion” was barely visible and almost transparent under regular microscope light sources (transmitted and reflected). Therefore, a 365 nm UV light was employed to check whether the foreign object fluoresced, and in fact it did (figure 2).

Figure 3. Three fibers under 365 nm UV light. A: Cotton handkerchief used to remove oil from the surface of the stone. B: Net fiber in which emeralds are placed for the enhancement process. C: Jewelry cleaning cloth also used to remove oil from the surface. Photomicrograph by Javier Toloza.
In the authors’ opinion, the fiber could only have come from one of three sources: a cotton handkerchief, a microfiber jewelry cloth, or the net used during the immersion of the stones in the enhancement container of the oiling machine. The first two would imply that a piece of fiber got stuck to the surface of the stone before the enhancement procedure took place, which is highly unlikely. The third source seemed the most plausible. In order to test that hypothesis, three strains of fibers were collected and compared using Raman spectroscopy with a Horiba HR Evolution with the laser operating at 532 nm. Although the spectra showed peaks in the 500 to 1500 cm–1 range, they were not specific for either of the fibers. Using the Olympus BX 41 microscope at 1000×, the diameter of the fiber was measured, and there was consistency with the diameter of the fiber collected from the net, about 50 μm. A 365 nm UV light source was also used to differentiate among them. A clear difference was evident between the nylon fiber from the net and the other two fibers (figure 3). This second test corroborated the authors’ hypothesis. Source: GIA @topic:3


Title: Flux-Induced Fingerprints in Flame-Fusion Synthetic Sapphire Abstract: Figure 1. Face-up view of the 2.81 ct flame-fusion synthetic sapphire with flux fingerprints. Photo by Diego Sanchez.

The Carlsbad laboratory recently received a blue cushion mixed cut measuring 9.07 × 7.07 × 4.62 mm (figure 1). Standard gemological testing gave a refractive index of 1.760–1.768, consistent with sapphire. Microscopic examination uncovered a fingerprint resembling those found in natural sapphires (figure 2). Closer examination revealed the fingerprint to be a flux fingerprint. When the stone was immersed in mineral oil, curved color banding diagnostic of flame-fusion lab-grown sapphire became visible (figure 3).

Figure 2. This flux fingerprint in the lab-grown sapphire is similar to the fingerprints found in natural sapphire. Photomicrograph by Nathan Renfro and Michaela Stephan; field of view 1.76 mm.

Figure 3. When immersed in mineral oil, curved color banding is visible along with a natural-looking flux fingerprint and large gas bubbles. Photomicrograph by Nathan Renfro and Michaela Stephan; field of view 7.19 mm.
Typically, a flame-fusion-grown ruby or sapphire with healed fractures has undergone a process known as “quench crackling,” where fractures are created in the stone by heating and subsequent rapid cooling. This stone did not show the characteristic cellular fracturing created by this process, making the healed fractures appear even more natural. The randomly fractured stone had been immersed in a flux melt. The flux melt filled and partially healed the fractures while the stone gradually cooled, which resulted in natural-looking fingerprints of residual flux. This treatment is usually seen in flame-fusion synthetic rubies (K. Schmetzer and F.-J Schupp, “Flux-induced fingerprint patterns in synthetic ruby: An update,” Spring 1994 G&G, pp. 33–38). Source: GIA @topic:3


Title: Iridescent Inclusions in Scapolite Abstract: Figure 1. Orange platelet inclusions give this 2.21 ct scapolite an orange color and aventurescence similar to that of Oregon sunstone. Photo by Jonathan Muyal.

	A 2.21 ct phenomenal scapolite (figure 1), reportedly from Tanzania, was recently examined by this author. Of particular interest was its striking resemblance to Oregon labradorite feldspar, which displays aventurescence and is known in the trade as sunstone. Raman microspectrometry confirmed the stone’s identity as scapolite. Vibrant thin-film iridescence created by brownish orange exsolution platelets (figure 2) was revealed by microscopic examination; these platelets are responsible for the stone’s orange bodycolor. The exsolution platelets are presumed to be hematite based on their color, morphology, and high levels of iron detected by energy-dispersive X-ray fluorescence (EDXRF), although it was not possible to confirm this identity through Raman analysis. This scapolite’s aventurescence and pleasing orange bodycolor make it an interesting collector’s gemstone.

Figure 2. Under magnification with oblique illumination, the platelet inclusions reveal vivid multicolor iridescence. Photomicrograph by Jonathan Muyal; field of view 1.42 mm. Source: GIA @topic:2


Title: Unusual Yellowish Green Spinel Abstract: Figure 1. This 2.54 ct yellowish green spinel is shown under daylight conditions (left) and short-wave UV light (right). Photos by Sood Oil (Judy) Chia (left) and Jian Xin (Jae) Liao (right).

Gem-quality spinel (MgAl2O4) occurs in a variety of colors based on the trace elements present within the stone. While synthetic spinels are available in almost any color, some colors are rarely found in natural spinel. The New York lab received a 2.54 ct light yellowish green spinel with unusually strong green fluorescence (figure 1). This variety of color, along with the strong fluorescence (in both long-wave and short-wave UV radiation) is rare in natural spinel, and we needed proof that this stone was not synthetic.

A refractive index of 1.715 suggested the stone might be natural (flame-fusion synthetic spinels typically have an RI of 1.728). Microscopic examination revealed a very small fingerprint shallow to the table facet. While not conclusively diagnostic for natural origin, it supported the possibility. When observed under cross-polarized filters, the stone revealed very little strain, more consistent with a natural spinel. To confirm natural origin, PL spectra and trace element chemistry data were collected.

The PL spectra were collected at room temperature, using 514 nm laser excitation. The sharp and defined chromium emission features, with the strongest peak at approximately 685.5 nm (figure 2), verified that the stone was natural and unheated (S. Saeseaw et al., “Distinguishing heated spinels from unheated natural spinels and from synthetic spinels,” 2009). Heat treatment typically broadens and shifts the position of PL peaks (a similar effect is seen in synthetic spinels). Using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), high concentrations of natural trace elements were measured—particularly lithium, gallium, zinc, and beryllium. This reinforced our finding that the spinel was natural.

Figure 2. Well-defined chromium emission features in the photoluminescence
spectrum confirm natural, unheated spinel.
The stone also exhibited relatively high levels of manganese and iron. Fe can play various roles as a chromophore in spinel, depending on coordination within the crystal structure (divalent substitution of Mg and trivalent or divalent substitution of Al), but it is mostly responsible for different shades of blue and greenish blue (V. D’Ippolito et al., “Color mechanisms in spinels: cobalt and iron interplay for the blue color,” Physics and Chemistry of Materials, Vol. 42, 2015, pp. 431–439, http://dx.doi.org/10.1007/s00269-015-0734-0). Mn (divalent substitution of Mg and trivalent substitution of Al) is known to act as a yellow chromophore (among other colors) in spinels (F. Bosi et al., “Structural refinement and crystal chemistry of Mn-doped spinel: a case for tetrahedrally coordinated Mn3+ in an oxygen-based structure,” American Mineralogist, Vol. 92, 2007, pp. 27–33, http://dx.doi.org/10.2138/am.2007.2266). The combination of Fe and Mn within the crystal structure provided a transmission window in the green region of the visible spectrum (figure 3). Using a charge-coupled device (CCD) detector and a long-wave UV light source, the green fluorescence emission band was calculated to be centered at approximately 520 nm. This luminescence was attributed to Mn2+ cations (Summer 1991 Lab Notes, pp. 112–113). The fluorescence could have contributed to the overall color of the stone by adding more green hue through emission.

Figure 3. In the spinel’s UV-Vis-NIR absorption spectrum, the combination of iron and
manganese peaks produces a transmission window in the green region of the visible
spectrum.
This was one of the most unusual colors of spinel examined by GIA. Source: GIA @topic:3


Title: Phosphorescence of Synthetic Sapphire Abstract: Figure 1. Left: The 1.14 ct synthetic sapphire under daylight-equivalent lighting. Photo by Sood Oil (Judy) Chia. Right: The sample exhibited phosphorescence in this DiamondView image. DiamondView image by Akhil Sehgal.

Phosphorescent features in synthetic colorless sapphires have previously been reported in G&G (Fall 2013 GNI, pp. 182–183). A 1.14 ct colorless sample was recently submitted to the New York lab for identification (figure 1, left). The gemological properties determined the stone was corundum. The specimen was free of inclusions, with no detectable gas bubbles or curved striae. Quantitative chemical analysis, showing a lack of gallium as well as iron levels below the detection limit, indicated that the sample was synthetic. The material was also transparent to short-wave ultraviolet radiation, whereas natural colorless sapphires do not transmit short-wave UV light due to the quenching effect from trace impurities (S. Elen and E. Fritsch, “The separation of natural from synthetic colorless sapphire,” Spring 1999 G&G, pp. 30–41). This is the same test used to effectively separate type I and II diamonds; nitrogen impurities in diamonds are strong absorbers of light in the short-wave UV range between 225–320 nm (C. M. Breeding, “The ‘type’ classification system of diamonds and its importance in gemology,” Summer 2009 G&G, pp. 96–111). The UV-visible spectrum shown in figure 2 also illustrates the transparency with the absorption edge at approximately 216 nm, whereas natural near-colorless sapphires typically have an absorption edge around 300 nm.

Figure 2. Transparency was observed in the UV-Vis-NIR spectrum.
Figure 3 illustrates the phosphorescence band centered at approximately 424 nm, along with other minor decay bands observed in the visible spectrum that mix together to produce the blue phosphorescence observed in figure 1 (right). The phosphorescence lasted about 25 seconds, until the excited electrons dissipated. The only trace elements detected with LA-ICP-MS were Ti (21 ppma average), and Cr, Mg, and Ca (below 5 ppma). Chalky blue fluorescence in sapphires is believed to be due to Ti4+ charge-transfer transition of isolated Ti4+ ions or Ti-Al vacancy pairs. The fluorescence peak is usually between 410 and 420 nm, but shifts to higher wavelengths as Ti concentrations increase (B. D. Evans, “Ubiquitous blue luminescence from undoped synthetic sapphire,” Journal of Luminescence, Vol. 60–61, 1994, pp. 620–626; W.C. Wong et al., “Charge-exchange processes in titanium-doped sapphire crystals. I. Charge-exchange energies and titanium-bound exitons,” Physical Review B, Vol. 61, No. 9, 1995, pp. 5682–5698). The phosphorescence in synthetic colorless sapphires could be related to this property, with the addition of the decay route including forbidden energy transition states. Phosphorescence in synthetic colorless sapphires is still not well understood, and additional research is needed to verify the origin of this phenomenon.

Figure 3. The phosphorescence spectrum of the synthetic sapphire shows the main band
centered at approximately 426 nm, along with smaller bands in the visible-light region. Source: GIA @topic:4


Title: Guest in Garnet: Metal Sulfide? Abstract: An opaque crystal, likely a metal sulfide, is suspended in a garnet. A combination of darkfield and oblique fiber-optic illumination makes it appear as though the crystal is hovering inside the stone. Portions of the inclusion are duplicated because of its split across several facet junctions, adding to the visual interest. Photomicrograph by E. Billie Hughes; field of view 4 mm.
Recently a faceted garnet containing a striking inclusion came across the author’s desk. The solid inclusion was opaque with a metallic luster and had an uneven surface containing numerous sharp protrusions (see above). Although we were unable to definitively identify the inclusion, its opaque dark nature and crenulated texture were consistent with a metal sulfide crystal.
This inclusion scene inspired a variety of imaginative comparisons at our laboratory. Some thought it was reminiscent of the fire-breathing piranha plants from the Super Mario franchise, while others suggested it resembled a Ferrero Rocher chocolate. Regardless of what we might see in this piece, it is certain that we will continue to be fascinated by the delightful whimsy of Mother Nature’s micro-world. Source: GIA @topic:3


Title: “Smoke Rings” in a Non-Beryllium-Diffused Sapphire Abstract: This “smoke ring” pattern was observed in a heat-treated blue sapphire. While this pattern is commonly associated with beryllium-diffused blue sapphires, no beryllium was detected in this stone. Photomicrograph by Nicole Ahline; field of view 7.39 mm.
When analyzing corundum for evidence of heat treatment, one of the most useful and standard methods for gemologists is microscopic examination (N.D. Renfro et al., “Inclusions in natural, synthetic, and treated sapphire,” Summer 2017 G&G, pp. 213–214). Inclusion suites can start to alter at temperatures as low as 200°C. As the temperature rises, many inclusions start to show clear evidence of heat treatment, such as the internal diffusion of titanium, resulting in a spotty blue color, and discoid tension cracks with healed fringes around crystals. Standard temperature heat treatment for corundum happens between 500° and 1700°C, whereas high-temperature heat treatment, such as beryllium diffusion, occurs at temperatures above 1750°C. These high temperatures can modify inclusions in a way that renders them unidentifiable, suggesting that a stone may have undergone beryllium diffusion.
While examining a heated blue sapphire recently, the author observed “smoke ring” inclusions throughout it (see above) using fiber-optic illumination. Trace element chemistry analysis of the blue sapphire via laser ablation–inductively coupled plasma–mass spectrometry revealed no signs of beryllium. This came as a surprise, as this dislocation pattern is associated with beryllium-diffused corundum. These “smoke ring” dislocations are consistent with sapphires that have been heated at high temperatures, but chemistry ruled out beryllium diffusion treatment. This sapphire offers a striking example of why continuous documentation of inclusions, in both treated and untreated gemstones, is an important tool in gemstone analysis. Source: GIA @topic:3


Title: Dyed Fluorite Abstract: Figure 1. These two rough pieces weighing 454.27 and 358.03 ct were identified as dyed fluorite. Photo by Annie Haynes.
Two pieces of green rough weighing 358.03 and 454.27 ct (figure 1) were recently sent to the Carlsbad laboratory for an emerald identification and origin report. Standard gemological testing could not be performed due to the rough surfaces and size of the stones. Raman spectroscopy was used to aid in the identification (figure 2), and the Raman spectra were consistent with the mineral fluorite.

Figure 2. Overlay of the Raman spectra of one of the dyed fluorite samples
and a known emerald sample.
Internally and externally, both pieces showed typical massive habit fluorite features. Small octahedral crystals were scattered along the surfaces, and perfect cleavage in four directions was documented. Cleavage is not a gemological property of emerald, and octahedral cleavage is a key identifying feature for fluorite. Weak color banding could be seen with diffused lighting, but the most abnormal observation with both of these stones was the presence of obvious dye concentrations along their fractures (figure 3).

Figure 3. Obvious dye concentrations within surface-reaching fractures. Photomicrograph by Nicole Ahline; field of view 7.26 mm.
Fluorite naturally comes in a wide range of colors and can have multiple colors in a single crystal. These stones are a careful reminder to analyze every stone thoroughly for proper identification and to detect the most uncommon of treatments. Source: GIA @topic:2


Title: Polymer-Treated Hessonite Abstract: Figure 1. These three rough hessonite samples (17.92 grams total) are joined by a polymer, which is also found in surface cavities and joints. The treatment is evident from the rough’s “oily” look. Also note the visibility of fractures in the 5.31 ct (left) and 5.35 ct (right) cut samples. Photo by Gagan Choudhary.

	Early in 2016, gem merchant Abdul Hafiz (Jaipur, India) showed this contributor a parcel of orangy brown rough hessonite he had purchased, said to be “glass-filled” hessonite. Upon initial observation, the specimens appeared to be treated, as individual crystals were stuck together (figure 1). This is commonly seen in glass-filled corundum rough; however, the typical glassy surface was absent. Rather, the surface appeared greasy, as if it was heavily oiled. Since the crystals were stuck together, it was obvious that some more stable form of treatment has been performed. Further testing was conducted to identify the treatment.

	Under 10× magnification, the joints and cavities showed a concentration of a foreign substance that was readily indented with a metal pin, ruling out the presence of glass. Because of the unpolished surface, we could not see the  filler, but the stone was transparent enough for infrared spectroscopy. The spectra showed strong features at approximately 3060, 3032, 2923, and 2871 cm–1; these peaks are associated with polymer. Other absorption features were consistent with grossular garnet, specifically hessonite and tsavorite, according to the laboratory’s database.

	To check for a polymer filler and record gemological properties, two specimens were faceted, weighing 5.35 and 5.31 ct, respectively (again, see figure 1). Both specimens gave an RI of 1.745 and a hydrostatic SG of 3.60, within the range for hessonite (M. O’Donoghue, Gems: Their Sources, Descriptions and Identification, 6th ed. Butterworth-Heinemann, London, 2006). Both displayed a strong roiled or “heat wave” effect and numerous transparent rounded to elongated colorless crystals, features consistent with hessonite. The stones had obvious fractures visible to the unaided eye. When magnified, these fractures displayed thick and cloudy patches (figure 2), suggesting that a foreign substance was used to create an uneven filling. None of the iridescence or color flashes typically associated with a filled fracture were visible. Both faceted stones also displayed characteristic polymer-related peaks in IR spectroscopy.

Figure 2. Fractures of the cut samples display thick and cloudy patches, suggesting uneven filling. Photomicrograph by Gagan Choudhary; image width 6.35 mm.

	This was our first encounter with a polymer-treated hessonite. Because the fractures were eye-visible, it is unclear how much value the treatment adds to these low-grade stones. According to Mr. Hafiz, the treatment is performed to stabilize the rough for cutting and polishing; otherwise the highly fractured material crumbles while processing. He added that hundreds of kilograms of such rough (reportedly African) have been sent to China for treatment. Source: GIA @topic:3


Title: Topaz Description Abstract: This selection of gems from Ouro Prêto, Brazil, and Russia's Ural Mountains, displays the golden orange to pinkish red color range of precious topaz. The gems range from 7.61 to 14.33 carats in size.

                      Many consumers know topaz as simply an inexpensive blue gem. They’re surprised to learn that its blue color is hardly ever natural: It’s almost always caused by treatment. They might also be surprised to know that topaz has so many more colors to offer gem lovers, including pinks and purples that rival the finest fancy sapphires.

	This superb reddish purple pear-shaped topaz from Brazil's Capão mine displays the gem’s top color. - Courtesy Dr. Wagner Colombarolli
Topaz is allochromatic, which means that its color is caused by impurity elements or defects in its crystal structure rather than by an element of its basic chemical composition. The element chromium causes natural pink, red, and violet-to-purple colors in topaz. Imperfections at the atomic level in topaz crystal structure can cause yellow, brown, and blue color. Brown is a common topaz color, and the gem is sometimes mistakenly called “smoky quartz.”

	So far, commercial deposits of imperial topaz are found in a single area of the world: Ouro Prêto in Brazil. The 6.00-carat pear shape and 3.82-carat antique cut display nuances of the gem's color. - Courtesy Suwa & Son

	Against the light, this crystal's color zones and high clarity stand out clearly. It might be possible to fashion a unique gem from this piece. - Courtesy Dr. Wagner Colombarolli
Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colorless topaz is plentiful, and is often treated to give it a blue color.

	Topaz crystals are typically elongated, with grooves parallel to their lengths. For this reason, they're commonly cut into long oval or pear shapes. These crystals show orange, pink, and brown colors. - Eric Welch/GIA
The color varieties are often identified simply by hue name—blue topaz, pink topaz, and so forth—but there are also a couple of special trade names. Imperial topaz is a medium reddish orange to orange-red. This is one of the gem’s most expensive colors. Sherry topaz—named after the sherry wine—is a yellowish brown or brownish yellow to orange. Stones in this color range are often called precious topaz to help distinguish them from the similarly colored but less expensive citrine and smoky quartz.

Topaz is also pleochroic, meaning that the gem can show different colors in different crystal directions. Source: GIA @topic:1


Title: Update on Sapphire Mining in Ilakaka-Sakaraha, Madagascar Abstract: A parcel of sapphire and chrysoberyl from the Ilakaka-Sakaraha deposit in southern Madagascar. Photo by Vincent Pardieu, © GIA.

Introduction
In July-August 2010 and August 2012, this contributor visited southern Madagascar to collect reference samples from the Ilakaka-Sakaraha deposit, probably the world’s largest sapphire producer over the past 13 years. This update presents a map of the mining areas. Note that all the sapphire-producing localities are associated with sandstone areas.

The first discovery happened in 1998, near Ilakaka Be. Because the village was near Route Nationale 7 (RN7), the main road linking the capital city Antananarivo to the port of Toliara, the locals quickly found a thriving market with Thai and Malagasy merchants. Within months, miners from around the island settled near the bridge on the Ilakaka River, and a boomtown was born. Ilakaka is a much quieter place today. Tourists regularly stop there, while Sri Lankan, Thai, and Malagasy gem traders still conduct business.

A map of the Ilakaka-Sakaraha mining areas of southern Madagascar.
Many gemologists and traders are surprised by the extent of the deposit. Discoveries occurred beyond the Ilakaka area on the Malio and Fiherenana River basins in the north and on the Benahy, Taheza, Imaloto, and Onilahy River basins to the south and west of Ilakaka (basins are separated by yellow dots on the map). As the map shows, the deposit extends about 120 km east from Anena (on the Onilahy River) to Anakondro (on the Imaloto), and nearly 100 km north from Anena to Antaralava (on the Fiherenana) and Anakondro to Ankaboka Malio (on the Malio).

While sapphires were also reported north of Antaralava near Fotilovo and Murarano and in the Malio Valley north of Ankaboka Malio, this contributor has not explored these remote areas.

Ilakaka River Basin: The discovery near Ilakaka Be fell short of its early promise, and within months activity moved upstream to Ambarazy, which was briefly an important trading center, and the famous Banque Suisse mining site, one of the largest pits ever dug by hand in Madagascar. Mining also occurred north of RN7 on the western side of the Ilakaka River, up to the village of Bepeha. Mining was not allowed on the eastern side of the river, which is part of Isalo National Park. While small groups were still active at Banque Suisse in 2012, mining had nearly stopped elsewhere in the basin. Besides a few groups working around the town, a small Thai mechanized operation is still at Amabrazy. Overall, some 300 people were still mining in the Ilakaka River basin, a fraction of the estimated 60,000 there in 1999.

Eastern Boundary and Imaloto River Basin: Very few sapphires have been found beyond the eastern limit of the sandstone-related rocks. The only exceptions are the secondary deposits along the Imaloto, near Lovokadabo, Ampasimamitaka, Sakabe, Ambotzove, and Ankondro, where sapphires were trapped in river sediments, probably transported from sandstone-covered regions by the Ilakaka and Benahy Rivers. In 2012, the area along the Imaloto seemed to be producing again after several relatively quiet years. Gems were also found in several areas closer to Sakalama. A rush occurred in 2004 at Ampasimamitaka, where the sapphire-rich Benaha River joins the Imaloto. A parcel of mostly milky blue sapphires mined there were later found to contain natural beryllium. In 2008, it was difficult to find miners anywhere except Sakabe. Returning in 2012, the contributor witnessed a rush near Sakalama, with about 200 people at two large pits. Nearby at Mahavily, another 100 were reportedly mining on the Benahy River. At Ampasimamitaka, about 50 people were mining on the Imaloto. Other groups were reportedly working upstream to Lovokadabo, but also far downstream. At Ankondro, 50 km downstream near Benenitra, about 50 people were digging for pink and blue sapphires. Another 200 were said to be near Ambotzove. In 2012, we estimated 500 to 1,000 miners on the eastern side of the region, mostly along the Imaloto.

View Gallery

Western Boundary, Sakaraha to Bezaha: The western boundary links Sakaraha, south of the Fiherenana River, and Bezaha, on the Onilahy River. West of that the geology is dominated by limestone-, basalt-, and gabbro-rich areas where gems are found in two areas, carried by the rivers from the sapphire-rich sandstone-covered region between Sakaraha and Ilakaka.

In the northwest near Antaralava, at the intersection with the sapphire-rich Fiherenana River, a narrow sandstone-rich area extends north to south between two regions containing limestone. Mining started in 2000, and in 2012 about 50 people were there.

In the southwest near Anena, on the Onilahy River, a minor rush occurred in 2005, and five years later about 100 miners were believed to be at the site. Anena is the only known deposit south of the Onilahy, a deep, powerful river not currently mined for gems. The discovery at Anena and the fact that the sapphire-rich Ilamoto and Taheza Rivers flow into the Onilahy suggest that this river is abundant with sapphires. Yet the area is too remote to attract the mechanized mining needed to work the deep sands.

Benahy River Basin: Mining along the Benahy started in 1999. The village of Vohimena soon became famous, and several mechanized operations were there from 2000 to 2011. In March 2005 an important discovery happened near Sakameloka, an area that became known for pink sapphires. Several other mechanized operations followed until late 2007, when prices for small pink rough in the Ilakaka market reportedly dropped 90% from the year before.

Other mining villages lower on the Benahy, such as Morafena, were too remote to explore. Visiting the area from Sakameloka down to Vohimena Mahafala in 2012, the contributor observed fewer than 500 miners along that portion of the Benahy. The mechanized operations seen there from 2005 to 2010 had ceased.

	Sapphire miners pose with their hand tools at a site on the Benahy River near Sakameloka. Photo by Vincent Pardieu, © GIA.
Malio and Fiherenana River Basins: In late 1999, mining started north of RN7 in the Fiherenana and Malio River basins near Ankaboka Malio, Analamahavelona, Betikely, Maromiandra, Ankaboka Ambinany, Andralanova, Bevilany, and Antaralava. Several Thai companies were operating machinery near Ankaboka Ambinany and the bridge at Bevilany. After the 2003 discovery of significant deposits near Manombo Be, Sri Lankan buyers opened offices there to intercept the sapphires before they reached the Thai buyers in Ilakaka.

By 2005, Manombo rivaled Ilakaka, but most of the evening activity now happens at nearby Sakaveero, the trading center built circa 2007. Activity north of RN7 was reportedly weak in 2010, but in August 2012 about 1,000–1,500 locals using hand tools were scattered north of the road, including areas of the Zombitze-Vohibasia National Park. About 400 miners were south of Manombo Be at Manombo, Misereno, and Anduharano. Near Analamahavelona, the discovery of fine blue and pink stones in May 2012 attracted some 400 miners. Near Ankaboka Ambinany, a few hundred people were working different deposits around the villages north of the Bevilany Bridge, where a Thai mechanized operation used two excavators and a washing plant. Another few hundred were reportedly at Ankaboka Malio and other remote areas of the Malio River.

Taheza River Basin: Since about 2000, sapphires have been mined along the lower Taheza north of Bezaha and in the upper valley. Mining villages sprang up at Analasoa, Analalava, Mahasoa, and Ambalavihy, where tens of thousands were reportedly working. Mining rights were soon acquired by large Sri Lankan companies. After attempting to mechanize, they decided to buy stones from locals instead, supporting them with food and tools. This model became very successful in the Taheza basin, and by 2008 it was probably the main sapphire region in the whole deposit. While activity in the upper basin has declined, it has increased near Antsoa, where about 5,000 people were mining and washing gravels in 2011 and 2012. In 2011 the main mining area was Mangatoka, but the next summer it was Ankaranduha, where more than 1,000 were working. In the Taheza basin the sapphire-rich gravels are usually about 30 meters deep, but some artisanal miners used a 50-meter vertical shaft to reach the gravels, which were mined by digging narrow horizontal tunnels. For the digger to breathe, air had to be sent underground using large plastic bags and tubes. The gravels were extracted and taken to the river for washing.

	A sapphire miner works with hand tools in the Taheza River at Analalava. Photo by Vincent Pardieu, © GIA.
Due to the lack of roads, activity could not be observed on the Taheza south of Ambatomainty, where there were remnants of Sri Lankan operations. From Bezaha up to Ankilivaly, the contributor explored the lower Taheza basin in 2010 and 2012 and saw mining near Ankilitelo, Ambarinakoho, and Ankilivaly. A gem rush occurred at Ambalmasai in late 2011, and the following year about 500 people were still mining that remote area. Some activity was also reported at Sarouval, about 5 km north of Ambalmasai on the other side of the Taheza. At each site, Sri Lankan companies supplied the miners with loading trucks, tools, and food.

In 2012, most of the production from western Ilakaka-Sakaraha was along the Taheza, in the area south of Manombo, near Vohimena, and in a few spots north of RN7. Sapphire trading followed the same trend. Ilakaka was quiet except for the morning gem market and late at night when people offered the stones they were unable to sell at Sakaveero, the popular new trading spot.

Overall, mining and trading around Ilakaka is down from previous years. But with 10,000–20,000 miners and several hundred buyers, Ilakaka-Sakaraha probably still surpasses Ratnapura and Elahera in Sri Lanka as the world’s main source for blue and pink sapphires. From April to July 2012, many of the buyers and miners left Ilakaka to work in the jungle near Didy and Ambatondrazaka, where fine rubies and sapphires were discovered in March 2012. Most of them returned to Ilakaka in July when the new site (located in a protected area) was closed by the authorities, and by August business was mostly back to normal. Source: GIA @topic:1


Title: Cat’s-Eye Nephrite Jade from Washington State Abstract: Figure 1. This 1.71 ct cat’s-eye nephrite marquise (11 × 5.5 mm) was mined in Washington State. Photo courtesy of Washington Jade.

Washington Jade (Edmonds, Washington) made its Tucson debut at the AGTA show with nephrite jade from Washington State. They offered a selection of cabochons with and without chatoyancy, along with carvings and rough collectors’ stones. The cat’s-eye nephrite (figure 1) was the most popular by a wide margin, according to Washington Jade’s Nathaniel Cook. Rod Cook, his father and business partner, said that according to many at the show the chatoyancy was reminiscent of the Siberian nephrite that dominates the mid- to high-end Chinese nephrite market.
Cat’s-eye nephrite is found only in Washington and Russia; a deposit in Taiwan has been mostly depleted. While nephrite has been found in northwest Washington since the early 1900s, formal production was limited to an operation west of Darrington, near Everett, that ended in the 1970s. Chatoyant nephrite was documented there in 1974. Since then there has been an artisanal “gray market” for nephrite, with people collecting illegally from streams and state lands, but no formal production. This changed in 2012 when Washington Jade began staking claims. Most of their production comes from a deposit northwest of Darrington.
Washington Jade uses innovative small-footprint mining methods instead of more invasive traditional methods. To identify a jade seam, they use pattern recognition to look at geologic models of the area, along with biological indicators such as tree species and lichen growth. Magnetic and conductivity surveys are used to locate the high-grade portion of the seam. With these methods they can develop a 3D model of the subsurface and focus on the high-grade deposits, in contrast to the traditional model of core drilling, digging up an area with heavy equipment, and taking out all the jade to be sorted by grade. They take only the high-value materials, leaving the rest in the ground. Rod Cook said they backfill and replace the plants after extracting the jade, leaving a very small footprint.
British Columbia is the leading supplier of nephrite, but Washington’s deposits, part of the same geological formation, have yet to be developed. The domestic jade market is much smaller than the Asian market, where jade has been part of Chinese culture for thousands of years. Nathaniel Cook said the nephrite market overall has tightened recently and prices have come down after steady growth the past two decades, but people were still surprised by what they saw as a low price point for the cat’s-eye material.
Rod Cook said there has been an explosion of artisanal jewelers using nephrite. The cat’s-eye nephrite is popular with them, though market acceptance is still in the early stage. He noted that Washington Jade’s output is large enough to meet domestic demand and could be scaled up to the level needed for a jeweler with a few hundred stores. He sees a trend toward jewelry with “less bling” and said that millennials seem to prefer carved material over faceted.

Figure 2. View from inside the “jade cave” on one of Washington Jade’s mining claims. The ceiling appears to be a vein of chatoyant nephrite. Near the opening is another vein, the first couple feet of which provided the rough for many of the stones at the AGTA show. Photo courtesy of Washington Jade.
The Cooks also discovered a “jade cave” (figure 2) in a 200-foot canyon cut by a stream. The jade exposed there informs their geologic models by allowing them to see what a similar structure looks like deep in the ground. The cave formed when a piece of the main chatoyant seam broke loose, slid down the hill, and fell into the stream along one side, creating a tunnel underneath. During the spring melt, water flowed through and created a hydraulic plume, which washed away the overburden on one side and revealed a 2-foot-wide seam of chatoyant jade traveling up into the mountains. Rod Cook estimates there are 30 to 100 tons of chatoyant jade in the cave’s immediate vicinity, and they have confirmed outcrops of the main nephrite lode containing the chatoyant seam for 1,500 feet over two of their 23 claims. Based on their discoveries so far, he estimates that the main lode is 150 to 300 feet wide and “goes for miles.” Source: GIA @topic:12


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

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

Figure 2. Fluid inclusions in a step-like pattern running parallel to the base of the rhodochrosite cabochon. Photomicrograph by Nicole Ahline; field of view 4.14 mm.
Asterism is created when light is reflected off well-aligned inclusions and returns as a star across the surface of the stone. Such stones are commonly cut as cabochons to properly display this phenomenon. The asterism seen in this rhodochrosite was created from fluid inclusions that run parallel to the base of the cabochon (figure 2). The fluid inclusions were rhomboid in shape, which caused the star to have four rays. It is worth noting that the rays of the star did not cross perpendicular to each other, and this is due to the rhomboid fluid inclusions intersecting at an angle not at 90°.
Many gemstone species display asterism, but this was the author’s first opportunity to see a star rhodochrosite. This 19.44 ct stone is a perfect example of why one should always keep an eye out for the unexpected. Source: GIA @topic:3


Title: Exceptionally Large and Well-Saturated Orange Sapphire Abstract: 31.06 ct well-saturated orange sapphire measuring 18.65 × 13.85 × 11.81 mm. Photo by Diego Sanchez.

The Carlsbad laboratory recently received an exceptionally large orange cushion mixed-cut sapphire weighing 31.06 ct (see above) submitted for an identification and origin report. Standard gemological testing gave a refractive index of 1.769–1.762 and a hydrostatic specific gravity of 3.98, indicating corundum. This sapphire exhibits a saturated orange color that is attributed to the trace element magnesium in the stone’s crystalline structure. Microscopic examination showed altered crystals with healing and irregular bands of particles. These altered inclusions suggest that the stone underwent heat treatment. Internal characteristics similar to these are often found in sapphires from deposits of metamorphic sources. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) confirmed the stone had a lower content of trace element iron. The chemistry and internal features of this gemstone indicate an origin of Sri Lanka.
Rough material that will cut large, high-quality sapphires is rare, with most finished stones being less than five carats. Fine gem-quality examples of more than ten carats are considered very rare. The combination of a large size and a well-saturated orange color makes this 31.06 ct sapphire a notable gemstone. Source: GIA @topic:1


Title: Cat’s-Eye Calcite from Pakistan Abstract: Figure 1. This 57.60 ct calcite from Pakistan shows a cat’s-eye. Photo by Jaroslav Hyršl.

              Cat’s-eye calcites have been sold at auctions and gem shows for some years, but a gemological description of the material has not been published. Low-quality cat’s-eye calcites do exist, such as blue calcites from Mogok, Myanmar, but their chatoyancy is weak. It was very surprising, therefore, to see sharp chatoyancy on the beautiful calcite cabochon in figure 1.

The stone, purchased during the Tucson shows in February 2015, came from the Baluchistan province of Pakistan. It weighed 57.60 ct and measured 25.0 × 24.6 × 12.3 mm. It was light green and translucent, without eye-visible inclusions. The spot RI ranged from 1.48 to 1.66, and when rotated the cabochon showed a strong “blink” typical for carbonates. This is significant because the stone resembled chrysoprase; without the rotation, the measured RI in a given position might also approximate that of chrysoprase. There were no lines in the visible spectrum, the stone was inert under UV light, and its specific gravity was 2.72. Viewed in the polariscope, it remained bright, indicating a doubly refractive aggregate. Strong banding (figure 2) was present in the direction of chatoyancy, but the bands were inclined at about 20° angles. The bands were approximately 0.7 mm thick.

Figure 2. Banding in chatoyant calcite from Pakistan, as seen through the bottom of the cabochon. Photo by Jaroslav Hyršl.
Only at 40× magnification did the cause of the chatoyancy become apparent. Numerous tiny needles perpendicular to the chatoyancy were likely evidence of a columnar to needle-like texture. Other than the chatoyancy, this specimen is similar in appearance to the green and orangy yellow calcites from Pakistan that were described in the Fall 2012 GNI section (pp. 217–218). It is the opinion of both the seller and the author that this calcite is from the same locality. Source: GIA @topic:2


Title: Fossil Insect in Opal Abstract: Figure 1. A polished free-form opal encapsulating an insect. Play-of-color is shown at the bottom. Photo by Jian Xin (Jae) Liao. Stone courtesy of Brian Berger.

The authors recently examined a most unusual opal. The mottled brown polished free-form stone appeared to contain a trapped insect, which one might expect to find in fossil amber or copal (figure 1). However, noticeable play-of-color made it obvious that the host material for the insect was precious opal, which was further confirmed by standard gemological testing. Its refractive index of 1.45, weak white long-wave fluorescence, and Raman spectrum were all consistent with natural opal. No microscopic evidence of any type of treatment was detected.

Figure 2. An unidentified insect encapsulated in opal. Left: A head and mouth are visible along with several legs covered in fine hair-like structures, or setae. The leg in the foreground was partially cut through during polishing. Field of view 6.39 mm. Center: Setae branching from an appendage; field of view 2.57 mm. Right: The thorax of the insect is visible, though partially contorted. A grainy white layer coats and partially obscures the surface-reaching appendages and abdomen. Field of view 11.50 mm. Photomicrographs by Nathan Renfro (left and center) and Tyler Smith (right).
Play-of-color was strongest in the darker brown portions toward the base but also appeared in shallow fissures around the insect’s appendages. The insect broke the surface, resulting in some of its legs and underside being cut through during polishing (figure 2, left). An apparent set of mouth parts was clearly observed, but the position of some pits on the surface partially obscured the view. Fine hairs, or setae, were found along the legs (figure 2, center). The setae closest to the surface were surrounded by a grainy white material that resembled desiccated opal. A slightly contorted abdomen was observed alongside a pair of rear legs (figure 2, right).
Precious opal formation is not fully understood, but several mechanisms have been proposed (B.Y. Lynne et al., “Diagenesis of 1900-year-old siliceous sinter (opal-A to quartz) at Opal Mound, Roosevelt Hot Springs, Utah, U.S.A.,” Sedimentary Geology, Vol. 179, Nos. 3-4, 2005, pp. 249–278; B. Pewkliang et al., “The formation of precious opal: Clues from the opalization of bone,” The Canadian Mineralogist, Vol. 46, No. 1, 2008, pp. 139–149). One possible explanation is that low-pH groundwater percolated through the soil, accruing colloidal silica into a silica-rich fluid. This gel then underwent polymerization within cavities and voids to form microspheres of opal-A. One could imagine a scenario where the insect was entrapped by an intrusion of this gel, rapidly enveloping the insect and allowing it to avoid decomposition.
While fossilized organic matter in the form of roots and twigs has been found in precious opal—most notably in Virgin Valley, Nevada, and Wollo, Ethiopia—this is the first confirmed case of an opal-encased insect that the authors have examined. We were not able to find any other recorded findings, although there have been rumors of them. It is our hope that more specimens are discovered so we can more thoroughly study these exceptional rarities. Source: GIA @topic:11


Title: Blue Opal from Chile Abstract: Figure 1. Left: A polished Chilean blue opal pear-shaped cabochon displaying a uniform and strongly saturated medium blue color and a greasy luster. Right: An oval cabochon representative of the typical color palette and banding, varying from bluish green to slightly greenish blue and pure white, which produces a “seascape” image. Photos by Cristiano Brigida; courtesy of Chilean Rocks and Minerals.
Opal is an extremely popular stone in its many phenomenal varieties. However, the market also offers countless types of nonphenomenal opal, whose selling point is their combination of color, pattern, and degree of transparency.
At the 22nd Street show, the author came across an enchanting ocean blue variety of opal from Chile, exhibited by Chilean Rocks and Minerals. The material on view was opaque to semitranslucent with an overall color banding and greasy luster, tumbled or cut as cabochons. The most prized pieces contained slightly greenish and vivid blue colors (figure 1, left). Less valuable polished stones showed alternating blue and solid white layers or the presence of green material and sometimes brown matrix in their bands. The cutters used the natural banding to their advantage, resulting in attractive colors and patterns that often evoke pleasant seascapes (figure 1, right). After cutting, the material is polymer impregnated to create a tough and durable finished product.

Figure 2. Rough sample of Chilean blue opal, about 18 cm wide, displaying a dull conchoidal fracture, alternating green and blue bands, some white lenses (milky quartz), and a light brown matrix. Photo by Cristiano Brigida; courtesy of Chilean Rocks and Minerals.
A selection of various grades of rough material was also available, displaying a dull conchoidal fracture with the dominant textural feature being the intricate interplay of blue and green, the two main colors (figure 2).
According to the dealer, this was the debut of cut Chilean blue opal at the Tucson gem shows. This type of opal is reportedly from the Atacama region, the only known occurrence to date in Chile, where a few mining operations are actively extracting the material. Presently known to the trade is a blue opal from Peru referred to as “Andean opal,” but that material is generally translucent and lower in saturation than the Chilean blue opal.
No detailed mineralogical analyses on the samples exhibited at 22nd Street have been reported. The blue color could be due to internal light scattering and dispersed chrysocolla, a mineral known for its vivid blue hue. Chrysocolla is commonly found in copper-rich deposits such as the porphyry copper deposits in the Atacama region. The analogy with Peruvian blue opal, which comes from a similar chrysocolla-rich geological setting, supports this hypothesis.
Given its vibrant color saturation, ability to take a high polish, and the desirable texture and alternating color patterns of the cut stones, this Chilean blue opal was a pleasant new addition to the gem offerings from Tucson 2024. Source: GIA @topic:11


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

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

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


Title: Sugar/Heat-Treated Opal Abstract: From left to right: rough Andamooka matrix opal, a slice after treatment, and a 72 ct finished freeform cabochon. Photo by Tao Hsu; courtesy of Unconventional Lapidarist.
Treatments can cause harm when they are not disclosed properly, but without treatments, fewer gem resources would find their usage in the jewelry trade. At the AGTA show, the authors had the rare opportunity to talk with James Carpenter from Arkansas-based Unconventional Lapidarist about sugar/heat treatment on porous rough opal.
Sugar and acid treatment is one of the most commonly used methods to enhance opal. In the trade, this treatment is usually applied to matrix opal from Andamooka, Australia, a particularly porous material. The finished product is often referred to as “Andamooka matrix opal” or “Andamooka rainbow matrix opal” by the trade. This treatment was presented as a hot sugar bath followed by a hot acid bath (G. Brown, “Treated Andamooka matrix opal,” Summer 1991 G&G, pp. 100–106). The chemical reaction between sugar and acid then deposits carbon to the porous structure of the opal as black dots. The treatment darkens the background color of the opal and therefore makes the play-of-color stand out more.
Carpenter revealed that he treated the opal without using acid to gain a similar result. The opals, either slices or cabochons, were first soaked in a hot 50% sugary water solution for 6 to 9 hours. After cooling down from the hot sugar bath, the pieces were patted dry and then tightly wrapped in aluminum foil. Carpenter emphasized that tight wrapping is especially important because a loose wrap causes the sugar to sweat out and possibly generate more cracks in the material. The well-wrapped materials were then heated in a toaster oven at 450–500°F for about 4 hours. After the final cooling, the materials were polished to finished products or retreated if necessary, revealing a dramatic change from start to finish (see above). Source: GIA @topic:11


Title: Inclusions and Spectroscopic Features of Yellowish Green Enstatite Abstract: Figure 1. Two faceted and four cabochon bright yellowish green enstatites. Left to right: a 1.02 ct pear (sample no. e102), 1.32 ct cushion (e132), 2.78 ct cushion (e278), 1.44 ct pear (e144), 0.65 ct oval (e065), and 0.67 ct modified triangle (e067). Photo by C. Kamemakanon; courtesy of American-Thai Trading.
Gem-quality enstatite is the magnesium end member of the enstatite-ferrosilite series in the clinopyroxene subgroup of the pyroxene group. While the most common color is brown, it can also be colorless, green, or gray. Myanmar, Tanzania, and Sri Lanka are the main sources of gem-quality stones currently in the market. Enstatite can yield clean faceted gems but can also display four-, six-, or eight-rayed asterism.
Enstatites have been documented many times from various sources. Six-rayed star brown enstatite was reported from India (W. Eppler, “Star-diopside and star-enstatite,” Journal of Gemmology, Vol. 10, No. 6, 1967, pp. 185–188). Sri Lankan samples were reported in U. Henn and H. Bank, “Sternbronzit aus Sri Lanka,” Zeitschrift der Deutschen Gemmologischen Gesellschaft, Vol. 40, No. 2–3, pp. 145–148. Star enstatite from Madagascar was described in T. Cathelineau, “Six-rayed star enstatite from Madagascar,” Journal of Gemmology, Vol. 36, No. 8, 2019, pp. 688–690. Four-rayed star brown enstatites from Sri Lanka were documented in E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 3, Opinio Publishers, Basel, Switzerland, 2008. Faceted brown enstatite was reported in Koivula et al., “Gemmological investigation of a large faceted East African enstatite,” Journal of Gemmology, Vol. 21, No. 2, 1988, pp. 92–94. Yellowish green enstatites from Africa were discussed in K. Schmetzer and H. Krupp, “Enstatite from Mairimba Hill, Kenya,” Journal of Gemmology, Vol. 18, No. 2, 1982, pp. 118–120, as well as in B.M. Laurs et al., “Yellowish green enstatite (and star enstatite) from Tanzania,” Journal of Gemmology, Vol. 36, No. 8, 2019, pp. 691–693. Norwegian stones were documented in F. Schmitz et al., “Polymer-filled star enstatite from Norway,” Journal of Gemmology, Vol. 35, No. 2, 2016, pp. 98–101.
Recently, GIT Gem Testing Laboratory (GIT-GTL) received six bright yellowish green enstatite samples weighing 0.65 to 2.78 ct (figure 1) that were reported by author SD to be from Africa. The stones appeared fairly similar to the previously documented four-rayed star yellowish green enstatite from Tanzania documented by Laurs et al. (2019). In that article, needle-like inclusions were found to be the cause of the four-rayed asterism, but their mineralogical identity was not reported.
Of the six stones examined in this study, four were cabochons displaying a four-rayed star effect while two were faceted (figure 1). The five stones with at least one polished flat surface gave refractive indices of α = 1.655–1.660, β = 1.661–1.665, and γ = 1.668–1.669, with a birefringence of 0.009–0.014, and are therefore biaxial positive. The spot RI reading of one cabochon without a flat surface was ~1.66. The hydrostatic specific gravity of all samples was 3.22–3.25. All these values fall well within the range of enstatite. The stones appeared weak orange under the Chelsea color filter and showed moderate yellow and yellowish green pleochroism. All were inert to both long-wave and short-wave UV.

Figure 2. A and B: Using oblique fiber-optic lighting, the four-rayed star enstatite cabochons reveal two sets of densely and regularly oriented fine needle-like inclusions intersecting at approximately 57° to 60°. C–E: The pear cabochon shows patches of densely oriented minute white particles (C), a plane of oriented tubes partially filled with small brownish white to colorless magnesite crystals (D), and oriented tubes filled with magnesite (E). F: Rectangular platelets and needle inclusions with bright interference colors in the modified triangle. Photomicrographs by S. Promwongnan; fields of view 3.6 mm (A–D) and 1.5 mm (E–F).
The main diagnostic internal features were the two sets of dense and regularly oriented needle-like inclusions (figure 2, A and B). The two sets measured on the same plane at the top of three cabochons (e278, e132, and e144) were found to intersect at an approximate angle of 57° to 60°, producing the four-rayed star effect seen on the cabochon surface (figure 1). While the two faceted stones also contained fine needle-like inclusions, they were not cut to display a star.

Figure 3. Raman spectra of the exposed fine needle inclusions plus host mineral (green line) show the superimposed peaks of rutile and enstatite that match with the RRUFF reference spectra (black and blue lines, respectively). Similarly, the spectra of exposed white to colorless crystals in short tubes plus host mineral (red line) display peaks of magnesite and enstatite that match with the RRUFF reference spectra (pink and blue lines, respectively).
Close examination also uncovered two sets of needles that did not produce asterism. In addition, patches of densely oriented minute white particles (figure 2C) and a plane of oriented short tubes (figure 2, D and E) were found in one stone (e144). These tubes were partially filled with tiny brownish white to colorless crystals identified by Raman spectroscopy as magnesite (figure 3). The presence of epigenetic magnesite (MgCO3) could have resulted from alteration of the host enstatite. The other feature consisted of sparse rectangular platelet inclusions occurring in various directions within the dense mesh of needle inclusions (e067, figure 2F).
The Raman spectra of all host mineral samples, recorded using 532 nm laser excitation, similarly showed dominant peaks that matched the enstatite reference spectrum from the RRUFF database (not shown here). Moreover, the Raman spectrum of the exposed fine needle inclusions plus host mineral in one sample (e078) gave the superimposed peaks of rutile (440 and 610 cm–1) and enstatite (238, 343, 662, 685, 1010, and 1030 cm–1), consistent with the RRUFF reference spectra in figure 3. Similarly, the Raman spectrum of exposed white to colorless crystals in short tubes plus the host in a sample (e144) showed overlapping peaks of magnesite (213, 330, 737, and 1094 cm–1) and enstatite, also consistent with the RRUFF reference spectra. The identity of the rectangular platelet inclusions, however, could not be resolved due to their sparsity and their depth below the surface.

Figure 4. Polarized UV-Vis-NIR absorption spectra of an enstatite (e132) showing a dominant Fe2+-related broad band around 900 nm and additional Fe2+-related absorptions at 1750 nm in addition to a continuous rise from ~700 nm toward the UV with smaller absorptions at 427, 506, and 546 nm. The iron absorptions are superimposed by two broad bands around 420–490 nm and 600–700 nm due to the presence of V3+ plus trace Cr3+ in the stone lattice (see table 1). Spectra are offset for clarity.
Polarized ultraviolet/visible/near-infrared (UV-Vis-NIR) spectra of a sample (e132) showed features dominated by broad absorption bands of Fe2+ in the NIR region centered at ~900 and ~1750 nm (figure 4). The spectra rise continuously from ~700 nm toward the UV with small Fe2+ peaks at 427, 506, and 546 nm in the visible range (Cathelineau, 2019). In addition, these iron absorption features were superimposed by absorption bands around 420–490 nm and 600–700 nm due to the presence of V3+ with trace Cr3+ (see table 1). These two bands cause the absorption of the violet-blue and orange-red ends of the visible spectrum. Such overlapping absorption features allow the transmission window in the green to the yellow region, giving rise to the bright yellowish green color (Laurs et al., 2019). The origin of the absorption band at ~2220 nm, however, could not be resolved.

Semi-quantitative EDXRF chemical analyses revealed enriched contents of silicon (58.1–59.2 wt.% SiO2), magnesium (26.5–31.5 wt.% MgO), and aluminum (6.3–8.1 wt.% Al2O3), with trace amounts of iron, calcium, titanium, vanadium, chromium, manganese, and zinc (table 1). Furthermore, the end-member compositions were calculated and appeared close to the enstatite end members (92.0–96.2% enstatite, 3.5–7.5% ferrosilite, and 0.3–0.5% wollastonite) of the enstatite-ferrosilite series.

In summary, the attractive bright yellowish green colors of these enstatites are caused by the combination of significant iron and vanadium with a trace of chromium substituting magnesium in the crystal lattice. The four-rayed asterism phenomenon is caused by light reflection from two sets of very dense fine rutile needle inclusions intersecting one another at approximately 57° to 60°. The similarity of these stones and those reported by Laurs et al. (2019) (tables 1 and 2) leads us to conclude these stones could also be from Tanzania. Source: GIA @topic:2


Title: Opal with Fluid Inclusion and Mobile Bubble Abstract: A Mexican opal containing a mobile gas bubble in the lower edge of the void (left). Tilting the stone causes the bubble to change position within the cavity (right). Photomicrographs by Jessa Rizzo; field of view 3.57 mm.

A Mexican opal was recently examined at the GIA laboratory in Carlsbad. The inclusion shows a euhedral void with a mobile gas bubble (see above). The void mimics the shape of a barite crystal that might have once been present in the opal. The barite crystal was likely dissolved during a dissolution phase during the growth of the opal, leaving behind only a fluid-filled void. Toward the end of the opal’s formation, the temperature decreased, causing the trapped fluid to separate into liquid and gas phases. Because of the small size of the bubble relative to the void, rocking and tilting causes it to move about. Fluid inclusions in opal are generally quite rare, and one with a mobile bubble is exceptional. Source: GIA @topic:2


Title: Books: The Collector's Guide to the Minerals of New York State Abstract: By Steven C. Chamberlain and George W. Robinson, 96 pp., softcover, illus., publ. by Schiffer Publishing, Ltd, Atglen, PA 2013. US$19.99.

                      From the outset, authors Steven Chamberlain and George Robinson acknowledge that their goal was not a field guide, but rather a guide for mineral specimen appreciation. On the whole, it succeeds in this aim, and is worth its moderate price for those cultivating an interest in minerals of the Empire State.

In the introduction, the first of four chapters, Chamberlain and Robinson provide a brief positioning of the mineral sources of New York State. While there are no localities as important as Mont Saint-Hilaire in nearby Canada or Franklin, New Jersey, but it is of note that (starting with warwickite in 1838) twelve new mineral species have been discovered in New York. Some have become world-famous for their beauty, like the Herkimer diamonds, which could soon be designated as the official state mineral.

The authors devote an entire page to the important collections and collectors of New York minerals since the early 19th century, but only one page of text (plus ten references) to the geology of New York State. The other pages of this sub-section contain beautiful photos, though most do not contribute much to the illustration of the subject. The most important geological takeaway is that almost all mineralogically interesting occurrences are found in either sedimentary or crystalline rocks and in fractures within these rocks.

The following chapters are devoted to the description of the mineral occurrences. In contrast to conventional field guides, which are usually organized geographically, this book groups the localities according to the geology of the host rocks: occurrences in sedimentary rocks, in crystalline rocks, and in fractures. This is perhaps the most unique feature of the book. The description of each locality discusses the same aspects: its significance to specimen mineralogy, its location and history, its geological setting and origin, and the relevance of the minerals to collectors. Each chapter ends with a listing of similar occurrences (with GPS coordinates) and references.

As both authors are recognized as specialists in New York minerals, these chapters are a treasure trove of information, especially as they attached importance to include the latest research results and modern mineral nomenclature (e.g., the brown tourmaline from Bush Farm has now been identified as fluoruvite).

The authors claim that the guide’s organization is “a new approach that brings coherence to relationships among similar localities.” This seems plausible and is certainly true to some extent, as the relations between similar occurrences become more visible. My overall impression, however, is that the advantages of this approach do not reach as far as the authors probably hoped.

Apart from minor criticisms (What is the interest of the lengthy enumeration of collections and collectors? Shouldn’t the part on geology be elaborated a little more, especially as the basic approach of the book is based on it?) one question immediately comes to mind: Can the minerals of an entire state be adequately described in just 96 pages, a quarter of which is filled with (admittedly beautiful) color photos? Obviously, the authors recognized this and chose to limit themselves to the most important occurrences: While this book is too incomplete to serve as a field guide or to act as a comprehensive local mineralogy text, its merit lies in the attempt at a new approach, the well-written and up-to-date text and the sheer beauty of the photos. Source: GIA @topic:7


Title: New Phenomenal Feldspar from North Carolina with Iridescent Inclusions Abstract: Brown and black exsolution platelets of hematite and ilmenite in feldspar (left) show colorful thin-film interference colors in oblique fiber-optic illumination (right). Photomicrographs by Nathan Renfro; fields of view 3.55 mm.
Several varieties of aventurescent feldspar are well known in the gem trade. Of these, one of the most remarkable is orthoclase from the Hart’s Range area in Australia. This unique material showcases exsolution platelets of hematite and ilmenite that display thin-film interference colors along the interface between the exsolution product and the feldspar host. Because of its array of colors and the crosshatch pattern of exsolution platelets, the material’s trade name is “rainbow lattice sunstone.”

The authors recently examined samples of potassium feldspar from a relatively obscure source (see above) that displayed a phenomenon remarkably similar to Australian rainbow lattice sunstone. This new material is reported to be from the Statesville area of North Carolina and contains brown and black exsolution platelets of hematite and ilmenite showing thin-film interference colors along the interface with the host feldspar. This deposit was first reported by George Frederick Kunz (Gems and Precious Stones of North America, The Scientific Publishing Co., New York, 1890, p. 164). Chemical analysis of the feldspar was performed using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), and the results were consistent with potassium feldspar.

Local prospector Ryan Underwood first found samples of this material as loose crystal fragments and traced them back to their source rock, a metamorphic biotite gneiss. The crystals are brittle, apparently as a result of metamorphic stresses, and tend to cleave during cutting. As such, material suitable for cutting is rare and finished stones tend to be small (though some large multicrystalline specimens up to 30 cm in diameter have been recovered). Base colors include blue-gray, tan, and a pink color apparently induced by additional fine hematite inclusions. Source: GIA @topic:2


Title: A New Treatment: Creating Phantom Structure in Opal Abstract: Figure 1. An 11.68 ct treated phantom opal in which the phantom structure appeared during experiments with various solutions. The sample is shown under daylight through the dome (left) and under halogen lighting through the bottom (right). Photos by Le Ngoc Nang.
Phantom structure in opal is a rare and interesting feature found only in Ethiopian opals (www.opalauctions.com/learn/opal-information/phantom-ghost-of-the-opal). The phantom consists of a large spherical inclusion, white and opaque, that is enclosed by transparent, yellow, or colorless host opal—whimsical names include “ghost,” “egg,” and “mother and daughter” opal. The exotic combination of precious opal surrounded by transparent opal renders this material more attractive and valuable. So far, there has been little research on its characteristics and formation.

Figure 2. There is no significant visual difference between an untreated Ethiopian natural phantom opal (left, 35 ct) and a treated phantom opal (right, 6 ct). Photos by Le Ngoc Nang.
At the end of 2021, while performing experiments on natural opal to test changes in transparency and the play-of-color effect with various solutions, the authors accidentally discovered how the phantom formed artificially in natural opal when immersing the stones in a mixture of water, oil, acetone, and other solutions (figure 1). As our curiosity continued to grow, we devised a treatment method to create a phantom in opal by adjusting the amount of solutions, time, and temperature. The phantom opal obtained by the treatment is visually similar to natural phantom opal (figure 2). The treatment is simple, but it creates a spectacular and bizarre structure that improves the stone’s appeal and value.
To reproduce the treatment process, we randomly selected an opal sample purchased from a jewelry store in Ho Chi Minh City (the seller did not know the gem’s origin). The oval cabochon weighing 19.0 ct was white in bodycolor and semitranslucent, with weak play-of-color (dull orange, yellow, green, and blue). The gem was tested before and after treatment using standard gemological methods and Fourier-transform infrared (FTIR) spectroscopy with a spectral range from 650 to 4000 cm–1 at Liu Gemological Research and Application Center. The refractive index was 1.45 (spot method), and the hydrostatic specific gravity was 1.72–1.85. The stone was inert to long- and short-wave ultraviolet radiation. Examination with a gemological microscope revealed many black inclusions that might be black magnetite. FTIR spectroscopy displayed major absorption bands at 779, 999, and 1638 cm–1. The gemological properties and FTIR analysis indicated natural opal.

Figure 3. Left: The opal before treatment is semitranslucent white and shows a weak play-of-color. Right: After 36 hours of treatment, the opal becomes transparent light yellow, containing a white phantom. Photos by Le Ngoc Nang.
After the gemological examination, the opal was soaked in a mixture of 90% vegetable oil and 5% ethanol, and the mixture was boiled at 80°C. Treatment time depended on the sample size and the expected size of the phantom. With longer heating time, more of the “phantom” was converted into transparent opal, resulting in a smaller center and larger surrounding transparent area. In this case, the author decided to treat the gem for 36 hours, and the finished artificial phantom was half the size of the host opal (figure 3). The shape of the phantom was similar to that of the host gemstone. Notably, the play-of-color area shrank after treatment. It went from covering the entire opal to just a thin layer at the outline of the phantom. Interestingly, the dull quality of the play-of-color did improve somewhat.

The characteristics of an opal sample before and after treatment are shown in table 1. Three distinct features can be used to identify the artificial phantom. The first is the morphological similarity between the host opal and its phantom. Second, the treated phantom opal strongly luminesces under long- and short-wave UV radiation as a result of the oil, while the natural opal is usually inert to weak green. Third, the FTIR spectra after treatment exhibit two additional significant peaks at 2853 and 2922 cm–1, attributed to the symmetric and asymmetric stretching vibration of the aliphatic CH2 group present in oil (N. Vlachos et al., “Applications of Fourier transform-infrared spectroscopy to edible oils,” Analytica Chimica Acta, Vol. 573–574, 2006, pp. 459–465). The third feature is also the most noticeable evidence that the sample has been treated with oil.
The treated sample was stored at room temperature under fluorescent lighting for three months to test the treatment’s stability. The phantom remained intact, leading the authors to conclude that the treatment stabilization is permanent under normal conditions. The apparent stability of the transparent opal may be explained by the impregnated oil in the stone, which evaporates slowly. To avoid damaging the treatment, however, careful handling is still advised when wearing a stone treated in this way.
In gem trading, treated products must be disclosed. Treated phantom opal may appear commercially in the future, so it is important to disclose our treatment process used to create a phantom structure by impregnating opal with oil and heat, as well as the means to identify the treatment. More importantly, this report is intended to avoid confusion between natural and treated phantom opal. Source: GIA @topic:11


Title: New Violet Orbicular Chalcedony from Ethiopia Abstract: Figure 1. This relatively new type of violet chalcedony from Ethiopia (here, 75–198 ct) displays a wonderful pattern of white orbs. Photo by Annie Haynes; courtesy of Orbit Ethiopia Plc.
At the GJX show, the author encountered a relatively new find of violet chalcedony reportedly discovered in Ethiopia in 2019 (figure 1). Processed and brought to market as tumble-polished freeforms, the chalcedony was offered by Orbit Ethiopia Plc. According to managing director Tewodros Sintayehu, the mine is located in the Gamo Zone region, approximately 600 km from Addis Ababa. The material was first discovered in the Gerese District and has since been found in the adjacent districts of Kamba and Garda Marta. Sintayehu noted that he had a very large quantity of the material stockpiled.

Figure 2. White orb-like structures were confined to a shallow surface layer in the violet chalcedony from Ethiopia. Photomicrograph by Nathan Renfro; field of view 15.16 mm.
The notable features of this material were its fairly vivid violet color as well as the multitude of white orbicular structures distributed across the surface of the gems (figure 2). Microscopic examination revealed that the white color was related to a distinct botryoidal structure where a shallow outer layer of the gems contained all of the white areas. Because the white orbs are confined to a shallow surface layer, this explains why the material was sold as tumble-polished nuggets: Cutting the material into cabochons would likely result in the loss of the white orbicular pattern. A few unidentified mineral inclusions were also observed with the microscope, but the cause of the outer layer’s white orb pattern remains unclear.
This new material is quite remarkable for its beautiful pattern. Even if it is only made available as freeform tumble-polished stones, it will be a welcome addition to the chalcedony market. Source: GIA @topic:2


Title: Microscopic Observations of Blue Sapphires Treated with Heat and Pressure Abstract: Figure 1. This sapphire that was treated with heat and pressure contained small birefringent crystals (left) that were nearly invisible with unpolarized light, as seen in the brightfield image (right). Photomicrographs by Nathan Renfro; field of view 1.81 mm.
In recent months, sapphires treated under heat and pressure have been documented in the trade. This material is reported to be treated under pressure of 1 kbar at temperatures between 1200 and 1800°C by HB Laboratory Co. Ltd. of Korea (H. Choi et al., “Sri Lankan sapphire enhanced by heat with pressure,” The Journal of the Gemmological Association of Hong Kong, Vol. 39, 2018, pp. 16–25). This process is used to improve blue coloration and potentially heal any fractures within the stones.
GIA acquired from Sri Lankan gem dealer Imam Faris of Imam Gems (Pvt) Ltd. six samples that were said to have been treated under the conditions mentioned above. The samples were examined using a standard gemological microscope to look for any unusual features resulting from this type of treatment. Five of the six sapphires showed a feature that to our knowledge has not been reported before. Viewed in polarized light (figure 1, left), planes of small crystallites were observed as bright spots against a dark background when the host corundum was in the extinct position. But under unpolarized light (figure 1, right), the crystallites were either invisible or nearly so, and only visible from a low-relief interface between the crystallite and the host corundum. Due to the extremely low relief of these inclusions, the author speculates that these inclusions are corundum crystals that originated from fractures and were healed by recrystallization of the corundum. While it is certainly possible to have birefringent crystals of corundum in untreated corundum, the consistent observation of the planes of birefringent crystals by the author suggests that this feature could be a useful indicator for corundum treated with heat and pressure. These preliminary observations offer some interesting clues, but further research will be needed to fully characterize corundum treated with this technique. Source: GIA @topic:3


Title: Separating Glass-Filled Rubies Using the DiamondView Abstract: Figure 1. A pair of rubies that were determined to be glass filled, partly with the assistance of DiamondView imaging. Photo by Lai Tai-An Gem Lab.

The treatment of gemstones using various filler materials is not new. In the case of corundum, silica glass was often observed filling rubies from approximately 1980 to the early 2000s, when it was largely replaced by high-lead-content glass in early 2004 (S.F. McClure et al., “Identification and durability of lead glass–filled rubies,” Spring 2006 G&G, pp. 22–34) which has since become the mainstream artificial filler in corundum. The Lai Tai-An Gem Lab in Taipei recently examined a pair of rubies (figure 1) that were quickly determined to be glass filled with the assistance of DiamondView imaging. In our experience, the DiamondView detects the presence of glass, although it does not distinguish between different types of glasses. This note shows how the DiamondView can be used to observe the presence and, perhaps more importantly, the degree of filling in rubies.
The two heart-shaped cabochons weighed 6.81 and 6.89 ct and measured approximately 10.78 × 13.55 × 5.39 mm and 11.36 × 13.10 × 5.47 mm, respectively. Each semitransparent stone exhibited a purplish red color and fluoresced a strong red to long-wave ultraviolet radiation while exhibiting a weak red reaction to short-wave ultraviolet irradiation. Standard gemological testing showed spot refractive indices of 1.76, and specific gravities of 3.94 and 3.93, respectively, which were lower than regular values and raised suspicion that the stones were filled, while advanced analysis by energy-dispersive X-ray fluorescence (EDXRF) and Fourier-transform infrared (FTIR) spectroscopy and Raman microscopy revealed data consistent with ruby. Magnification with a gemological microscope revealed natural fluid and fingerprint inclusions, but some evidence of a filler was also observed in the fractures.

Figure 2. Notable differences in the reflectance of the glass filling and corundum host were seen in the DiamondView’s visible light mode.

Figure 3. In contrast to figure 3, the DiamondView’s operational mode clearly revealed the glass-filled cavities as well as the extent of the glass (shown in blue) running throughout the rubies.
Under the DiamondView’s visible light settings, some surface-reaching filler features and filled “cavities” were also revealed. Notable differences in the surface reflectance between the filling material and surrounding corundum (figure 2) were clearly evident. After exposure to the DiamondView’s short-wave UV radiation, the treated nature of both rubies was even more apparent as the reaction not only showed the obvious cavities but the extent of the filler (in blue) running throughout the stones (figure 3). The 6.81 ct ruby revealed an even greater degree of filling than its twin, especially on the base where a greater concentration of filling material was noted.
As the DiamondView results prove, filler materials penetrate or remain on the fractures of the treated material (ruby in this case) under certain treatment conditions. Hence, some filling treatments may be revealed more clearly when exposed to the ultra-short-wave energy of the DiamondView. Chemical analysis of a filled area using EDXRF detected Si and Ba as the major elements. Minute levels of Pb were also obtained. The results proved the filler was a glass composed of these elements, which were not detected when other filler-free areas were analyzed.
Artificial glass is frequently used as a filling material in gemstones. The variable chemical compositions of these different glasses help improve the appearance (lower visibility of fractures) of the host after treatment. While the vast majority of glasses and other fillers, both organic and inorganic, can be detected with a loupe or microscope, the DiamondView is a useful identification aid should the need arise. Source: GIA @topic:3


Title: New Technologies of the 1980s: Their Impact in Gemology Abstract: The 1980s witnessed great development in the application of new technologies to gemology. These technologies provided new or better ways to grow synthetic gem materials and to treat natural ones. They also permitted numerous breakthroughs in gem identification, in areas where classical gemological methods were no longer sufficient to make a positive identification. In particular, various types of spectroscopy proved to be of important practical value, for example, infrared absorption, X-ray fluorescence, Raman scattering, and cathodoluminescence. Source: GIA @topic:1


Title: Iridescent Musgravite Abstract: Figure 1. This 0.86 ct gray musgravite displays an unusual iridescent phenomenon that is clearly visible in the table facet. Photo by Kevin Schumacher.

Musgravite is a rare mineral closely related by composition to the mineral taaffeite. This magnesium-rich beryllium oxide crystallizes in the trigonal system, in contrast to the hexagonal system of taaffeite, and is highly sought after by rare stone collectors. A 0.86 ct musgravite, identified by Raman spectroscopy, contained a particularly interesting inclusion scene consisting of numerous etch tubes that broke the surface of the faceted stone (figure 1). With a direct source of light, these etch tubes displayed vibrant colors resulting from thin-film iridescence in the air-filled, crystallographically aligned tubes (figure 2). This is the first musgravite gemstone displaying any type of optical phenomenon that this author has examined to date.

Figure 2. Thin-film iridescence along crystallographically oriented etch tubes was the source of the colorful phenomenon in this rare musgravite gemstone, viewed using oblique fiber-optic illumination. Field of view 2.47 mm. Photomicrograph by Nathan Renfro. Source: GIA @topic:3


Title: Zircon and Geikielite from Sri Lanka with Artificial Stars Abstract: Two asteriated cabochons acquired in Sri Lanka were identified as natural zircon and geikielite. But the six-rayed star had not been observed in natural star zircons, and the eleven-rayed star of the geikielite was crystallographically “impossible.” Microscopic observation clearly showed both had been created by a fine scratching of the cabochon domes.

										In both cases, the surfaces appeared to have been produced by short parallel scratches. The center of each star was a white spot, and their branches were short, sometimes missing or undulating and hatched. The effect is formed mainly by diffraction at the scratches rather than reflection from needles or hollow tubes, like in natural stones. When the focus of the microscope is lowered some millimeters from above the cabochon surface through below the surface, the star gets finer and is sharpest below the surface, in contrast to natural stars, where the sharpest star seems to hover above the surface.

										The features described above, along with some other characteristics mentioned by Steinbach (2011), allow a safe distinction of scratched star stones from their natural counterparts mostly by simple observation with the naked eye.

Abstracted by Rolf Tatje Source: GIA @topic:3


Title: Large Faceted Hibonite Abstract: This 134.43 ct faceted hibonite is the largest examined by GIA to date. Photo by Robison McMurtry.

	The Carlsbad laboratory recently examined an unusually large 134.43 ct opaque, very dark brown faceted hibonite (see above image). Standard gemological testing gave spot RI values of 1.79 to 1.81 and a hydrostatic SG of 3.81. Hibonite, which crystallizes in the hexagonal system, has published RI values of 1.790 to 1.807, but we were unable to observe birefringence, probably due to its opacity and these values’ proximity to the limits of the refractometer. The stone showed a high luster and was inert to long-wave and short-wave UV. Testing with a Geiger counter showed it was slightly radioactive. All of these features are consistent with hibonite, yet more advanced testing was needed for a positive identification of this unusual material.

	Raman spectroscopy gave a spectrum consistent with hibonite. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis revealed large amounts of Mg, Ca, Al, Ti, and Fe; small amounts of Na, Si, Sr, La, and Ce; and traces of numerous other elements, including the radioactive elements thorium (62.62–122.60 ppma) and uranium (0.12–0.56 ppma). The presence of these elements caused the mineral to react to the Geiger counter. The thorium and REE content is consistent with samples from Madagascar (M.A.F. Rakotondrazafy et al., “Mode of formation of hibonite (CaAl12O19) within the U-Th skarns from the granulites of S-E Madagascar,” Contributions to Mineralogy and Petrology, Vol. 123, No. 2, 1996, pp. 190–201).

	Microscopic examination revealed one deep green mineral inclusion breaking the surface of the table. Its Raman spectrum was consistent with spinel, a known associated mineral of hibonite. LA-ICP-MS analysis showed it was an iron-rich spinel within the hercynite(FeAl2O4)-spinel (MgAl2O4) series, with almost one-third of the magnesium substituted by iron. Although difficult to see internally, other whitish mineral inclusions were visible, as well as an extensive fracture and cleavage network.

	Orangy brown, transparent, and well-formed hexagonal crystals of gem-quality hibonite have been reported from Myanmar (T. Hainschwang et al., “Hibonite: A new gem mineral,” Summer 2010 G&G, pp. 135–138; Summer 2012 Lab Notes, p. 136). Although not gem quality, the stone’s size makes it a rare collector’s mineral as well as the largest hibonite GIA has identified to date. Source: GIA @topic:2


Title: Unusual Epigenetic Malachite Discs in Quartz Abstract: Figure 1. This 52.99 ct freeform cabochon of rock crystal quartz, reportedly from Brazil, contained several epigenetic discs of malachite. Photo by Robison McMurtry.

              When mineral-rich fluids become trapped in open cracks and evaporate, they can leave behind epigenetic mineral precipitates. These epigenetic mineral deposits are fairly common in gem materials, usually taking the form of brownish iron oxide staining in cracks. These deposits are often a nuisance, impairing the potential beauty of the finished gem, but occasionally they contribute vibrant colors with interesting geometric shapes, such as inclusions of pyrite trapped in cracks in quartz.

	Figure 2. These radial discs of epigenetic malachite were trapped within cracks of rock crystal quartz. Photomicrograph by Nathan Renfro; shadowed illumination, field of view 2.15 mm.
An unusual freeform cabochon of rock crystal quartz (figure 1), obtained from Leonardo Silva Souto (Cosmos Gems, Teófilo Otoni, Brazil) and reportedly of Brazilian origin, was examined at GIA’s Carlsbad laboratory. The 52.99 ct stone contained several interesting inclusions of malachite (figure 2). These inclusions were obviously epigenetic, as they were confined within secondary cracks in the quartz host. This planar confinement caused the inclusions to grow outward after nucleating. The flattened discs were particularly interesting due to the vibrant interference colors visible in polarized light (figure 3), as well as their uniform structure. The identification of the inclusions and the host was confirmed by Raman spectroscopy.

	Figure 3. In polarized light, these malachite discs showed vibrant interference colors. Photomicrograph by Nathan Renfro; field of view 2.15 mm.
Malachite has been previously reported as a syngenetic inclusion in chalcedony and gypsum (e.g., E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, ABC Edition, Zurich, 1986), but epigenetic malachite in quartz is rather uncommon. In this stone, the resulting vivid green color is an improvement over the otherwise ordinary, colorless quartz. Source: GIA @topic:2


Title: Australian Opal Beads with Blue Play-of-Color Abstract: At Tucson’s Globe-X show, these polished Australian opal beads (in sandstone matrix) displayed blue play-of-color. Photo by Donna Beaton.

	The Australian Opal Shop (Gold Coast, Australia) had a variety of goods on display at Tucson’s Globe-X Gem & Mineral Show. Owner John McDonald primarily deals in boulder opal with a sandstone matrix from the Winton mining area in Queensland. Untreated specimens can be polished to create beautiful slabs of boulder opal with or without matrix, though sandstone with microscopic bits of opal must be treated to make the play-of-color visible. The pieces are soaked in a fatty oil (usually vegetable oil) rather than petroleum-based oils, which leave a residue. The finished product ranges from multicolored to dark blue, depending on the size of the opal pockets and the spherical structure. What appears as dark blue bodycolor is actually blue play-of-color. The treated rough is usually fashioned into beads. Source: GIA @topic:11


Title: The Chinese Red Feldspar Controversy: Chronology of Research Through July 2009 Abstract: Red copper-containing plagioclase feldspar from Oregon has been available for over a century. In the early 2000s, new localities for copper-bearing feldspar were reported from the Democratic Republic of the Congo and from Tibet or an unspecified locality in China. The new material has been the subject of widespread concerns about its geographic origin and natural color. In fact, extensive studies of its composition, spectroscopy, physical appearance, and isotopic properties suggest that much of the red andesine on the market is the product of laboratory diffusion of copper into pale yellow andesine from Inner Mongolia. All samples initially subjected to testing as part of this study gave strong evidence or suggestions of treatment. Traces of copper-containing fluxes found on rough stones, and measurements of argon isotopic composition in particular, demonstrate that the tested material was recently heated to high temperatures under conditions where copper diffusion could occur. These results apply to samples that were obtained through July 2009, but do not include samples from expeditions to Tibet in 2010.

	DATA DEPOSITORY

Electron Microprobe Analyses of Red Andesine from Various Sources
	May 2, 2011 Source: GIA @topic:2


Title: Arsenopyrite in Smoky Quartz Abstract: Figure 1. Blades of the iron arsenic sulfide mineral arsenopyrite seen in a smoky quartz from the Huanggang mine in Inner Mongolia. Photomicrograph by Nathan Renfro; field of view 4.67 mm.
The authors recently examined a smoky quartz gem with interesting bladed inclusions of arsenopyrite (FeAsS), an iron arsenic sulfide mineral. The inclusions generally occurred as thick blades with striated faces in a dark gray color (figure 1). One such inclusion that was exposed to the surface and polished through showed a silvery gray coloration. Energy-dispersive X-ray fluorescence testing revealed significant amounts of iron and arsenic, consistent with the mineral arsenopyrite. The stone was reportedly from the Huanggang mine in Inner Mongolia, China. It was also reported that this stone was cut from a single large crystal that yielded approximately 20 such gems with arsenopyrite inclusions. Also present were numerous fluid inclusions, some of which showed vibrant thin-film interference colors in reflected light (figure 2). These are the first arsenopyrite inclusions the authors have examined in Mongolian quartz.

Figure 2. Fluid inclusions that showed vibrant interference colors in reflected light were also observed in the smoky quartz. Photomicrograph by Nathan Renfro; field of view 4.36 mm. Source: GIA @topic:2