Title: Saltwater Bead Cultured Pearl with Laminated Nucleus Abstract: Figure 1. A white round nacreous pearl weighing 28.89 ct and measuring 16.00 mm. Photo by Nuttapol Kitdee.

The nuclei used for bead cultured pearl production are usually spheres fashioned from nacreous shell (J. Taylor and E. Strack, “Pearl production,” in P.C. Southgate and J.S. Lucas, The Pearl Oyster, 2008, Elsevier, Oxford, UK, pp. 273–302). The majority of this shell is sourced from freshwater mussels found in the Mississippi and Tennessee River systems in the United States (L.E. Cartier and M.S. Krzemnicki, “New developments in cultured pearl production: Use of organic and baroque shell nuclei,” Australian Gemmologist, Vol. 25, No. 1, 2013, pp. 6–13), and the resulting nuclei typically range between 6.0 and 8.0 mm. When a white round nacreous pearl weighing 28.89 ct and measuring 16.00 mm (figure 1) was submitted to GIA’s Bangkok laboratory for identification, the gemologists were intrigued by what the X-rays revealed.
Externally, the pearl showed characteristics typical of bead cultured pearls originating from the silver-lipped variety of Pinctada maxima: large size, symmetrical shape, satiny luster, and white color. Preliminary observation with a loupe and microscope revealed faint and smooth overlapping nacre platelets with some surface blemishes and polishing lines. Energy-dispersive X-ray fluorescence (EDXRF) analysis failed to detect any manganese (Mn) but did reveal high levels of strontium (Sr), while X-ray luminescence revealed a moderate greenish yellow reaction. These results are consistent with those expected for saltwater cultured pearls containing a freshwater shell bead nucleus (H.A. Hänni et al., “X-ray luminescence, a valuable test in pearl identification,” Journal of Gemmology, Vol. 29, No. 5/6, 2005, pp. 325–329).

Figure 2. Real-time microradiography revealed two planes and two recesses (one in the center of each plane) within a large shell bead nucleus. In the optimal direction, one plane (red arrow) shows as a distinct dark line owing to the perfect alignment with the X-ray source relative to the detector, while the other plane (yellow arrow) is less well aligned and hence appears more like a discoid feature. Image by Kwanreun Lawanwong.
However, several interesting features were revealed by examination with real-time microradiography (RTX) (figure 2). The bead nucleus was clearly visible in the RTX images and measured approximately 10.21 mm in diameter. This uncommon size was the first indication that this was not a standard bead. Moreover, two sharp planes were clearly visible, another interesting observation since most shell bead nuclei examined with RTX do not show such defined bands. (These are not to be confused with the mostly weak and more diffused bands sometimes seen that relate to the shell’s layered growth structure.) The parallel lines matched structures observed in GIA’s previous research on known samples of bead cultured pearls in which laminated shell bead nuclei were used. In keeping with samples from that research, the most defined line appears when the nucleus is in the optimal direction (figure 2, red arrow) relative to the X-ray source and detector, while the less defined line (figure 2, yellow arrow) appears more like a discoid feature when the alignment is not so perfect. Additionally, a shallow and circular-looking recessed feature in the center of each plane aroused further curiosity. Such structures are not typical of other laminated beads previously examined by GIA.
Laminated shell bead nuclei originated a few decades ago when some Australian pearl farms attempted to produce large pearls to meet demand. However, the high price of the larger shell bead nuclei needed for this forced them to experiment with other materials such as dolomite (Summer 1998 Lab Notes, pp. 130–131; Winter 2001 Gem News International, pp. 332) to produce the large nuclei. Unfortunately, none of the materials were suitable from a commercial perspective. Some farms started bonding strips of shell together to fashion larger bead nuclei of around 10–10.9 mm. The majority of such pearls were produced from second operations. Since this experiment proved more successful, a number of saltwater bead cultured pearls possessing a laminated shell bead nucleus are still encountered in the market today.
GIA labs globally have encountered numerous laminated shell bead nuclei. However, this is the first example with the unusual recessed features, and the reason for their existence is unclear. They are unlikely to be related to damage caused during the manufacturing of the bead. The almost identical positions and appearances suggest that they were created for some purpose. Since the pearl is undrilled, damage resulting from any drilling process (Summer 1995 Lab Notes, pp. 125) may also be eliminated. Another possibility is that they may be related to placement areas for radio-frequency identification (RFID) chips (see Spring 2020 Lab Notes, pp. 134–136 of this issue). But since it is customary to only use one chip per pearl and the recesses are relatively thin with rounded outlines, which differ from the usual deeper square recesses encountered for RFID pearls, this seems unlikely.
The presence of faint banding within the nucleus and the pearl’s X-ray luminescence reaction prove that the bead was fashioned from freshwater shell. Therefore, even though the nucleus is laminated, the pearl is still classified as a “bead cultured pearl.” The only mystery left is the reason for the two shallow circular recesses in the surfaces of two of the shell pieces used to form the laminated bead nucleus. Source: GIA @topic:5


Title: Natural Pearls Reportedly from a Spondylus Species (“Thorny” Oyster) Abstract: Figure 1. Four non-nacreous pearls, weighing 12.40, 11.55, 8.22, and 5.72 ct (left to right), were submitted for identification. Photo by Sood Oil (Judy) Chia.

              Non-nacreous conch, clam, Melo melo, Cassis, and scallop pearls are often submitted to GIA for identification. Four non-nacreous pearls, weighing 5.72 to 12.40 ct and measuring from 9.55 × 8.60 mm to 16.35 × 9.36 mm, were recently submitted to GIA’s New York laboratory for identification. These examples caught our attention because of their unusual appearance (figure 1).

Their bodycolors and shapes varied. Each exhibited some degree of pink and orange hues, and either elongated or button shapes. The porcelaneous surfaces also exhibited areas with clear flame structures. Under fiber-optic light, fine flame structures resembling those seen in other porcelaneous pearls such as Tridacna gigas and Strombus gigas (conch) pearls were observed. While the typical whitish flame structure was readily apparent, the more notable observation was that some of the flames had a distinct blue coloration (figure 2). Other types of pearls usually do not show blue flames. Microradiography was of little diagnostic assistance, as only tight structures were observed; this is not unusual for porcelaneous pearls. Raman spectroscopy detected both aragonite and calcite separately on different parts of the samples. In the authors’ experience, this differs from conch or clam pearls, which are usually composed of aragonite only.

Figure 2. The porcelaneous surface appearances of two of the pearls, weighing 12.40 ct (left, magnified 20×) and 8.22 ct (right, magnified 10×) show their characteristic blue flames, indicated by the arrows. Photos by Joyce WingYan Ho.
Due to their unique shapes, colors, surface, and flame structures, we suspected these pearls were from one of the many Spondylus species (figure 3), commonly called “thorny” or “spiny” oysters. Although rarely encountered in GIA laboratories, Spondylus pearls have been documented in the past (Winter 1987 Lab Notes, p. 235; E. Strack, Pearls, Ruhle-Diebener-Verlag GmbH & Co., Stuttgart, 2006, p. 255), and some samples have been collected by the Qatar Museums Authority (H. Bari and D. Lam, Pearls, Skira Editore S.p.A, 2009, pp. 88–89). Our client later informed us that these specimens were found by a fisherman in shells of Spondylus princeps off the coast of Baja California, Mexico.

Figure 3. These shells are from various Spondylus species. Courtesy of GIA’s Bangkok laboratory. Photo by Nuttapol Kitdee.
This was a rare opportunity to see natural pearls from a known Spondylus species, and to document their unique gemological characteristics as references for mollusk identification in the future. Source: GIA @topic:5


Title: Cultured Pearl Market Update – Tucson 2014 Abstract: View Gallery

Cultured pearls shine
Fran Mastoloni (Mastoloni Pearls, New York City) updated us on the cultured pearl market during the AGTA show. He explained that for the past two years, the emphasis has been on long necklaces, double strands, and mixing different sizes, colors, and types of cultured pearls. These trends have reenergized the market, making pearls “fun to wear again.” While weddings and graduations are still occasions for classic akoya-type necklaces and studs, there are now more opportunities to sell innovative blends of color and shape. Typical of this approach is the striking necklace with 15–17 mm Tahitian baroque cultured pearls shown in figure 1 (left). Such a piece might take three years to make and could retail for tens of thousands of dollars.

With production of Tahitian cultured pearls down, Mastoloni has been using smaller off-round, pastel-colored pearls to create distinctive, competitively priced necklaces. These styles offer a “big” look for a relatively low price. The colors, including a subtle silvery gray, are all natural. Mastoloni stressed the importance of luster as a selling point.

South Sea cultured pearl production has been reliable and consistent in quality, but prices have fluctuated. While lower-quality specimens are inexpensive and readily available, high-quality pearls are expensive and difficult to obtain. Due to improvements in culturing processes—including the X-ray inspection of mollusks—baroque-shaped cultured pearls have become increasingly rare. When X-ray operators detect a non-round pearl, Mastoloni noted, they will restart the culturing process. As a result, fewer non-round shapes are available for baroque necklaces (figure 1, center).

Demand for fine cultured pearls from China has outstripped supply, with fine examples of all pearl types showing surges in price. Golden cultured pearls from the Philippines (figure 1, right) have become increasingly costly and difficult to obtain, Mastoloni noted.

View Gallery

Cultured beauty
This scarcity of cultured pearls made the necklaces exhibited by Mastoloni all the more remarkable. They included an exceptional strand of multicolor specimens from Australia, the Philippines, and Tahiti (figure 2), as well as a truly remarkable Burmese cultured pearl necklace that was the product of decades of labor (figure 3).

Mastoloni added that the cultured pearl industry has become much more competitive. Dealers require much more breadth of inventory: Simply having akoya or Chinese freshwater material is no longer enough. Customers are more educated and driven to seek out unique, striking pieces of different colors, shapes, or lengths—and want to see new variations and combinations every time they look to make a purchase. Source: GIA @topic:5


Title: Calcite Found on the Surface of a Saltwater “Nacreous” Pearl Abstract: Figure 1. A cream-colored button-shaped loose pearl weighing 2.32 ct, submitted for identification. Photo by Tony Leung.
The Hong Kong laboratory recently examined a loose pearl weighing 2.32 ct and measuring 8.45 × 7.27 × 5.36 mm (figure 1). Externally, the cream-colored pearl did not look out of the ordinary and exhibited a soft luster with a relatively clean surface. Examination through a binocular microscope revealed typical overlapping platelets, pits, and scratches. No coating, surface working, or other indications of treatment were observed (figure 2).

Figure 2. The pearl exhibited overlapping surface platelets typically found in nacreous pearls. Photomicrograph by Nick Chan; field of view 1.10 mm.

Figure 3. RTX examination revealed a clear boundary running across the pearl as well as structures associated with natural formation. Images by Cheryl Ying Wai Au.
Real-time microradiography (RTX) revealed a distinct boundary with twin growth structures consisting of normal growth layers that followed the shape of the pearl (figure 3). No structural characteristics of any known type of cultured pearl were observed, so the pearl was identified as a natural pearl. Energy-dispersive X-ray fluorescence analysis showed high levels of strontium and no traces of manganese. This, together with its lack of visible fluorescence to X-ray luminescence, confirmed its saltwater origin.

Figure 4. Raman spectra of three spots on the pearl’s surface exhibit main peaks at 156, 282, 712, and 1087 cm–1 that are diagnostic of calcite.
Despite the typical saltwater nacreous pearl surface appearance, Raman analysis on three random spots with 514 nm laser excitation revealed that the pearl’s platelet surface was composed of calcite rather than aragonite, with peaks at 156, 282, 712, 1087, and 1437 cm–1 (figure 4) (J. Urmos et al., “Characterization of some biogenic carbonates with Raman spectroscopy,” American Mineralogist, Vol. 76, 1991, pp. 641–646).
Nacreous pearls are typically composed of small polygonal tablets of aragonite arranged in laminar layers (L. Addadi and S. Weiner, “A pavement of pearl,” Nature, Vol. 389, 1997, pp. 912–915). Up until the examination of this specimen, Raman analysis on submitted pearls and research samples exhibiting overlapping platelet layers has always shown a mineral composition of aragonite. Calcite is usually found in the form of mosaic or cellular patterns on the surface of some types of pearls, or in the prismatic internal layers. This is the first time GIA has encountered a “nacreous-looking” pearl showing calcite when tested in different positions on its surface, which is unique and certainly worthy of note. Source: GIA @topic:5


Title: Strong Pinkish Purple Freshwater Bead-Cultured Pearls Abstract: Figure 1. This necklace of freshwater bead-cultured pearls from China displays strong pinkish purple hues with orient. Photo by Sood Oil (Judy) Chia.

Freshwater cultured pearls are known for their wide range of attractive colors, including different combinations of white, orange, pink, and purple hues (S. Akamatsu et al., “The current status of Chinese freshwater cultured pearls,” Summer 2001 G&G, pp. 96–113). Jack Lynch of Sea Hunt Pearls (San Francisco) recently submitted a necklace consisting of 33 strong pinkish purple near-round pearls, ranging from 11.90 to 13.85 mm in diameter (figure 1), to GIA’s New York laboratory. The unusually intense color and large size of the pearls immediately drew our attention. Mr. Lynch indicated that the pearls were farmed in both the Hunan and Hubei provinces of China, over a period of three and a half to four years.

Figure 2. Real-time X-ray microradiography analysis revealed the round shell bead
nucleus used to culture each of the pearls. Photo by Yixin (Jessie) Zhou.
Real-time X-ray microradiography (RTX) analysis revealed that all of the pearls in the necklace were bead cultured and had relatively thick nacre (figure 2). Energy-dispersive X-ray fluorescence (EDXRF) analysis detected a high concentration of manganese, confirming that these pearls were grown in a freshwater environment. Furthermore, Raman spectroscopy verified that their color was natural, with two strong peaks around 1130 and 1510 cm–1 associated with natural polyenic pigments found under 514 nm laser excitation (figure 3), consistent with previous studies (S. Karampelas et al., “Role of polyenes in the coloration of cultured freshwater pearls,” European Journal of Mineralogy, Vol. 21, 2009, pp. 85–97).

Figure 3. Raman spectroscopic analysis on the pearl’s surface showed two natural
polyenic pigment peaks at 1130 and 1510 cm–1.
Earlier Chinese production with large beads resulted in a high mortality rate. We continue to see larger bead-nucleated freshwater cultured pearls, so it appears that the process has greatly improved, either through better techniques or hybrid mollusks (D. Fiske et al., “Continuity and change in Chinese freshwater pearl culture.” Summer 2007 G&G, pp. 138–145). Pearls with larger size, a near-round shape, and intense coloration are highly sought after and more valuable than traditional products. The owner’s inquiries revealed that the pearls were formed under an extremely controlled environment and culturing procedures in mussels that produce the material marketed as “Edison pearls.” This necklace proves that current culturing techniques can achieve a wide range of vibrant hues, providing interesting and unique products for the market. Source: GIA @topic:5


Title: Iridescent Botryoidal Growth in Untreated Akoya Pearl Abstract: Iridescent and botryoidal subsurface growth seen in a pair of untreated akoya pearls. Note the nacre lines visible at the surface (top right of image B), giving context to the unusual growth and phenomenon below the surface. Photomicrographs by Britni LeCroy; field of view 3.57 (A) and 2.34 mm (B).
Cultured akoya pearls (Pinctada fucata) are typically admired for their high luster and desirable overtone. Nearly all pearls from this species undergo color treatment before entering the market. One untreated akoya pearl examined by the author exhibited an iridescent and botryoidal subsurface appearance when viewed with a fiber-optic light under microscopic magnification (see above). This was in sharp contrast to the pearl’s appearance without magnification, which showed a light gray bodycolor and smooth surface.
The light gray bodycolor of the pearl was caused by large voids or gaps surrounding its bead nucleus, which could be seen using real-time X-ray microradiography (RTX). Akoya pearls possess very thin nacre platelets that are transparent to translucent when viewed under strong lighting, allowing the viewer to see into the deeper layers of the pearl. The strong iridescence was caused by light interference within alternating layers of aragonite and conchiolin—the two substances that create nacreous pearls and that also have different refractive indices. Specifically, this iridescence is caused when incoming overhead light is reflected from the surfaces between the successive aragonite and conchiolin layers. When the reflected light rays from a bottom layer of nacre interfere with the incoming light, iridescence is created. In pearls, this feature is known as orient (E. Fritsch and G.R. Rossman, “An update on color in gems. Part 3: Colors caused by band gaps and physical phenomena,” Summer 1988 G&G, pp. 81–102). The underlying botryoidal structure combined with the iridescence from the overlying nacre was responsible for the unusual pattern or orient seen in this akoya pearl. This is the first time the author has encountered such a phenomenon in a pearl. Source: GIA @topic:5


Title: Natural Fossil Pearls and Shell Blister from the Coast of Florida Abstract: Figure 1. Three fossilized specimens recently submitted to GIA’s New York laboratory: two fossil pearls (12.64 × 11.50 × 10.00 mm and 13.08 × 11.45 × 10.18 mm, left and right, respectively) and a fossil shell (45.97 × 32.03 × 10.90 mm) containing a shell blister. Photos by Sood Oil (Judy) Chia; courtesy of Kathryn Malatino and Aaron Brown.

Fossilized shells and pearls represent a unique group of specimens that are occasionally submitted to GIA, as reported in G&G previously (Winter 2015 Lab Notes, pp. 432–434; Spring 2020 Lab Notes, pp. 136–138). Those fossil samples were usually brownish in color and fully petrified, lacking any surface structures and associated luster or overtones that once belonged to them. However, two cream-colored fossil pearls (along with a fossil shell containing a shell blister; figure 1) recently submitted to GIA’s New York laboratory completely changed our earlier impressions.
The two semi-baroque-shaped pearls measuring approximately 12.64 × 11.50 × 10.00 mm (weighing 8.64 ct) and 13.08 × 11.45 × 10.18 mm (weighing 9.48 ct) exhibited a dry, chalky appearance that would be expected for such old samples, with cracks and parasite holes (figure 2, right) detectable by visual observation. More remarkably, some surface areas had delicate nacre layers showing fine nacre platelet structures and displaying subtle iridescence effect, which could be considered as orient in nacreous pearls (figure 2).

Figure 2. Nacreous spiral platy structures, parasite tunnels, and orient effects were observed on the surfaces of the two fossil pearls. Photos by Joyce Wing Yan Ho (left; field of view 1.5 mm) and Emiko Yazawa (right; field of view 5.9 mm).
EDXRF analysis detected low concentrations of manganese and high concentrations of strontium, typical for marine mollusks. Raman spectroscopy identified the composition of the materials as aragonite. Microradiography revealed internal concentric and arc growth features, which confirmed their natural origin. Out of curiosity and due to the very good condition of the two pearls, we further extracted a small amount of powder from the surface of one pearl and sent it to the Accelerator Mass Spectrometry Lab at the University of Arizona for radiocarbon dating analysis. The dating work resulted in a δ13C value of –0.8 ‰, proving the sample to be very old. The fraction of modern carbon is less than 0.0024, indicating that the age of the sample was beyond the limit of radiocarbon dating (>48,500 years), though the actual age is unknown. This result proved that the sample could be categorized as fossilized material.
The shell that was submitted along with the two fossil pearls looked more petrified but also remained relatively intact, with obvious ridges (or scutes) on the back of the shell and a shallow cream-colored “bump” on the inner side that could best be described as a shell blister. According to the owner, these fascinating specimens were found off of the west coast of Florida near St. Petersburg, approximately 25–50 feet below the sediment during dredging, along with many more shells of various kinds and even fossilized shark teeth.
The two natural fossil pearls and the shell blister created by Mother Nature have been well preserved. They provided unique insights into ancient mollusks and their associated pearls or related materials. Source: GIA @topic:5


Title: Fluorescence Spectroscopy for Colored Pearl Treatment Screening Abstract: Figure 1. Treated pearls (left) with a similar range of colors as naturally colored pearls (right). Photo by Sood Oil (Judy) Chia.

Color is one of the most important value factors for pearls. Commonly applied treatment methods used to alter their color to increase commercial value include dyeing, irradiation, and bleaching. Unfortunately, the identification of some color treatments is challenging and time consuming. In this study, we tested the use of a fluorescence spectroscopy system to nondestructively inspect pearls by measuring their near ultraviolet (UV) response to visible fluorescence under mid-UV excitation.
When excited by deep to mid-UV (200 to 300 nm) light, naturally colored pearls emit a fluorescence band between 320 and 400 nm centered at 340 nm. This fluorescence feature may be attributable to the organic compounds contained within the nacreous layers (J. Hiramatsu et al., “Non-destructive assessment of the effects of heat and sunlight on akoya pearl quality,” Seibutsu Kogaku, Vol. 88, No. 8, 2010, pp. 378–383; F.W.J. Teale, “The ultraviolet fluorescence of proteins in neutral solution,” Journal of Biochemistry, Vol. 76, No. 2, 1960, pp. 381–388). It can be identified in all untreated pearls, corresponding to the UV absorption band around 280 nm (J. Yan et al., “Origin of the common UV absorption feature in cultured pearls and shells,” Journal of Materials Science, Vol. 52, No. 14, 2017, pp. 8362–8369).
Commonly applied color treatments such as dyeing and irradiation tend to damage or mask the conchiolin in the nacre, significantly reducing the fluorescence intensity. By evaluating the intensity of a pearl’s fluorescence in the UV region, it is possible to rapidly detect potential color treatments on pearls in a nondestructive manner.
A prototype fluorescence spectroscopy system was designed to measure the fluorescence signal in order to detect potential color treatments. A 275 nm UV light-emitting diode (LED) was used as the excitation source. The excitation light was guided by a bi-fabricated fiber probe to generate the fluorescence signal from the pearl sample, and the fluorescence signal was relayed by the same fiber probe to the detector. Finally, a spectrometer was used to disperse the fluorescence light emitted and monitor the response in the 300 to 700 nm range.
A set of 12 pearl samples was selected for evaluation. Figure 1 shows six treated-color pearls (left) and six naturally colored pearls (right). The samples included both freshwater and saltwater cultured pearls of colors frequently encountered in the market.

Figure 2. Fluorescence spectra of naturally colored and treated-color pearls. The horizontal axis represents the wavelength of the signal, and the vertical axis displays the signal level in normalized intensity.
Figure 2 shows the experimental results of this fluorescence measurement prototype. The horizontal axis indicates the fluorescence wavelengths from 300 to 550 nm while the vertical axis shows the normalized detector counts, which is the relative intensity of the signal normalized to the spectrometer’s integration time per millisecond. Based on the results, the six naturally colored pearls showed fluorescence signals in the UV region at least 2.5 times stronger than the six treated pearls. This characteristic feature may be a useful and rapid screening technique for gemological laboratories to detect color treatments in pearls. Source: GIA @topic:5


Title: Color Classification and Stability of Queen Conch Pearls Abstract: Figure 1. Six Queen conch pearls showing the differences in appearance between stronger (top) and weaker (bottom) saturation levels within the same hue. Three different hues are shown. Photo by Jian Xin (Jae) Liao.

Due to the ever increasing popularity and value of Queen conch (Lobatus gigas, formerly Strombus gigas) pearls, GIA has seen a steady increase in the number of conch pearls submitted to its various laboratories for identification. In response, this is an appropriate time to improve and expand upon GIA’s conch pearl color terminology in general and, more specifically, how it is applied to GIA Pearl Identification Reports.
To that end, GIA has redefined its approach to conch pearl color, so that it bears a stronger resemblance to the more refined process applied to GIA’s classification of nacreous pearls. Establishing and defining practical color boundaries has improved specificity and consistency in the description of conch pearl color opinions between all GIA gemologists and laboratories. In addition, the resulting conch pearl color classification system provides more precision in the communication of conch pearl color, for both the pearl industry and the public at large.
In order to be identified as Queen conch pearl, non-nacreous pearls that formed in the Lobatus gigas mollusk must fall into the red (pink) hues, namely reddish purple (extremely rare), purplish red, red, orangy red, and reddish orange. While conch pearls do occur in colors outside of this hue range, it is challenging to definitively identify them as such in a laboratory when they lack any red (pink) hue. Because the vast majority of Queen conch pearls fall into mid-tone and mid-saturation ranges, in the straight red hue, GIA (in keeping with the trade) has traditionally described conch pearl color in a much more general way than nacreous pearl color. The bulk of conch pearls were simply described as pink, unless the tone and saturation were significantly out of the mid-range in either direction (weaker or stronger). GIA’s current and historical data, as well as the studied sample materials, produced results that reinforced the notion that pink occurred most often, followed by Strong pink, Light pink, and Very light pink, with Red occurring very rarely. Some examples of these pearls are shown in figure 1.
In determining the boundaries for the different aspects (hue, tone, and saturation) of Queen conch pearl color classification, a number of resources were used. In addition to physical samples, we also used references from GIA’s database, with the application of color science, and from GIA’s color system for nacreous pearls. The goal was to create practical boundaries and color ranges that were discrete enough to differentiate between the obvious typical variances in conch pearl color, but would not be difficult to employ or understand. Once the accuracy of the boundaries was established, a “Conch Pearl Color Terminology Chart” was developed. This chart illustrates all of the boundaries, as well as the master pearl placement in the defined color space, and the designated color classification terminology.
A key issue that needed to be explored before expending the time, effort, and cost to create Queen conch pearl masters was color stability, especially with regard to the pink component; we have seen previously that such color can be modified under X-ray radiation. One quick illustrative experiment, where a piece of Queen conch shell was exposed to X-ray radiation under GIA’s X-ray luminescence instrument (100 kV, 3.2 mA, approximately 4 inches from the X-ray source), is presented here. The left side of the shell’s surface was shielded from the radiation, while the right side was exposed to X-rays. After 15 minutes of exposure, the apparent color of the shell turned from pink (left) to purplish (right), with reduced saturation (figure 2). A different result was observed when pink shell was exposed to short-wave UV radiation, for an extended time (after 4 hours), using a conventional 4-watt short-wave (254 nm) lamp. However, unlike the hue change observed in response to X-ray exposure, the effect observed using short-wave UV was a reduced saturation of the same hue (fading). No obvious changes were observed when the shell was exposed to long-wave UV radiation (365 nm) for 6 hours, although the effect of long-term exposure under long-wave UV radiation is still unknown. Exposure to sunlight and the fluorescent white light used for pearl classification also failed to induce any color changes.

Figure 2. Hue and saturation changes observed on a piece of Queen conch shell after 15 minutes’ exposure to X-ray radiation. The shielded area is to the left, the exposed area to the right. Photo by Sood Oil (Judy) Chia.
In addition, we recorded a real-time color change of a section of Queen conch shell exposed to X-ray radiation for 10 minutes, which clearly shows a gradual color shifting over this period. A ten-second time-lapse video is shown here, with the before and after appearance of the shell also shown at the end of the video. However, this experiment was strictly for research purposes, as the actual laboratory testing of Queen conch pearls only requires a very brief exposure of the samples under X-rays at minimal power settings necessary for examination of their internal structures. Proper shielding with lead is also used when multiple conch pearls are mounted in a single piece of jewelry, to avoid any unnecessary collateral exposure.

	Queen Conch Shell Exposed to X-Ray Radiation.

In summary, GIA has developed a consistent in-house color classification system and color masters for conch pearls, resulting in a comprehensive yet straightforward method to evaluate conch pearl color. While the color stability experiments clearly illustrate that the color of Queen conch shell and pearls may shift in hue and/or saturation under either X-ray radiation or short-wave UV radiation, GIA has long-standing precautions in place to mitigate the issue. Furthermore, the results showed that under standard lighting conditions, no discernible color changes were evident. Improved precision in describing conch pearl color facilitates better color consistency between GIA gemologists and the GIA laboratories. The clearer color terminology also allows buyers and sellers to communicate more accurately and effectively with each other. Source: GIA @topic:5


Title: Atypical Freshwater Cultured Pearls with Damaged Nacre Abstract: Figure 1. These four atypical freshwater cultured pearls with damaged nacre reveal one or more distinct nacreous layers underneath. Left to right: samples 1–4. Photo by Chunhui Zhou.

Recently the East Coast laboratory received four baroque-shaped pearls ranging in size from 9.07 × 13.50 × 14.03 mm to 9.32 × 11.34 × 15.77 mm  and weighing between 10.63 and 13.60 ct. On each of the four samples, the outermost surface nacre layers exhibited large holes and gaps, revealing one or more distinct nacreous layers underneath (figure 1). These underlying nacreous layers displayed good luster and overlapping platelet surface structures, and the large gaps between the inner and outermost nacre layers indicated that smaller pearls had been used as nuclei during the culturing process.
Further gemological testing by energy-dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma–mass spectrometry (ICP-MS) confirmed that both the outer and inner nacre layers originated from a freshwater environment. Some of these pearls contained widely varying amounts of trace elements (i.e., Mn and Mg) between the outer and inner layers, but previous studies have found that uneven distribution of trace elements can also occur in a pearl’s cross section (R. Lu et al., “Operational considerations of EDXRF, LA-ICP-MS, and photoluminescence techniques in the analysis of pearls,” Summer 2011 G&G, pp. 149–150).
Two did not show any distinct internal demarcation when examined with X-radiography in various directions (figure 2). This lack of a clear internal boundary may be due to multiple culturing attempts using the same pearl as a nucleus, which can cause overlapped internal structures and multiple distinct nacreous layers under the surface, as shown in the third sample. In addition, structures typical of non-bead cultured pearls were observed in these micro X-radiographs, suggesting that freshwater cultured pearls were used as nuclei during the culturing process.

Figure 2. X-radiographs show partial demarcation between the outer and inner structures of cultured pearls 1 and 2, but fail to reveal any clear boundaries in samples 3 and 4. Photo by Chunhui Zhou.
Finally, photographs of the X-ray fluorescence reactions of all four pearls were taken in a dark environment (figure 3). Various intensities of green and yellowish green fluorescence could be observed within each nacreous layer, presumably due to varying concentrations of manganese between layers and among the pearls themselves (H.A. Hanni et al., “X-ray luminescence, a valuable test in pearl identification,” 2005 Journal of Gemmology, 29, 5/6, pp. 325–329). More interestingly, reddish fluorescence was also observed around the damaged areas of the nacre in samples 3 and 4. This was possibly caused by foreign material between the “nucleus-pearl” and the outer nacre layers, which may also contribute to the lack of distinct demarcation observed in the cultured structure.

Figure 3. X-ray fluorescence images of the four cultured pearls showing various degrees of green or yellowish green fluorescence between inner and outer layers. Atypical orangy red fluorescence is also visible between the layers in samples 3 and 4. Photo by Chunhui Zhou.
While similar types of pearls with intact outer nacre surfaces have been reported on previously (E. Strack, “Chinese freshwater cultured pearls beaded with baroque freshwater cultured pearls,” Fall 2011 G&G, pp. 244–245), the ambiguous internal structures, interesting X-ray fluorescence properties, and large gaps in the outer nacre layers of these four samples offer a rare view of their internal physical structure and appearance, obtained free of destructive testing. Source: GIA @topic:5


Title: “Gran Dama” Brooch Featuring Large Melo Pearl Abstract: Designed by Gianmaria Buccellati, the “Gran Dama” brooch celebrates pregnancy through its centerpiece 98.67 ct Melo pearl. Photo by Orasa Weldon.

              After a surge in popularity during the 19th century, Melo pearls reemerged on the gem market in the 1990s. These exceedingly rare pearls are produced by the Indian volute, a sea snail indigenous to Southeast Asia. The pearls themselves are non-nacreous and found in shades of orange, yellow, gray, and brown. Upon acquiring a 98.67 ct Melo pearl, thought to be one of the largest in the world, acclaimed jewelry designer Gianmaria Buccellati created the “Gran Dama” brooch to showcase this exceptional gem.

Created to honor the power of pregnancy, the brooch epitomizes, in Buccellati’s own words, “the highest and purest, I dare say divine, human state.” While many years were invested in the concept design and inspiration, the brooch itself required three years to complete, from original design to finished piece. The Melo pearl, representing the womb of the expectant mother, is accentuated by its setting in yellow, pink, and white gold, surrounded by 410 round brilliant diamonds and 139 fancy-color diamonds. The pear-shaped, 18.21 ct South Sea cultured pearl used for the brooch’s head provides a striking visual contrast with the orange, spherical pearl at the centerpiece of this work of art. Source: GIA @topic:15


Title: The First Identified Non-Nacreous Beaded Cultured Pearl Abstract: Figure 1. A parcel of natural pen pearls surrounds a 6.92 ct non-nacreous beaded cultured pearl. Photo by Olivier Segura.

              The Laboratoire Français de Gemmologie (LFG) recently had the opportunity to examine a collection of non-nacreous pearls from the Pinnidae family (Pinna and Atrina species). Among these, one black pen pearl drew our attention for its relatively large size: a 10.6–10.6 × 9.6 mm round button weighing 6.92 ct.

Its dark black porcelaneous appearance was typical of pearls from the calcitic part of Atrina vexillum, the kind usually submitted for laboratory analysis (figure 1). Observation at 85× magnification (figure 2) revealed a distinctive pattern of convolution, with a few micro-cracks.

Figure 2. Surface magnification of the non-nacreous beaded cultured pearl revealed a typical calcitic pattern of pen pearls. Photo by Olivier Segura; magnified 85×.
Our findings on these cultured pearls are similar to those of N. Sturman et al. (“Observations on pearls reportedly from the Pinnidae family [pen pearls],” Fall 2014 G&G, pp. 202–215) in terms of Raman spectra (confirming the calcitic nature), UV-Vis spectra, and chemical composition.

The most interesting findings came from X-radiography. Microradiography/tomography imaging clearly shows a bright white disk inside the pearl (figure 3). The continuous separation line around this feature leaves no doubt that there is a bead inside the cultured pearl. As the beads used to nucleate “nacreous” pearls typically come from large freshwater mussels, we know that they are of a slightly denser material than saltwater nacre. Thus, they appear whiter than the surrounding material (of saltwater origin). The bead’s appearance was consistent with a classical nucleus of the kind used in bead-nucleated pearls. Measurement of the bead gave a 6.70 mm diameter.

Figure 3. This microradiograph clearly identifies the pen pearl as a beaded cultured pearl. Image by Olivier Segura.
Tomography confirmed the presence of a near-perfect spherical bead inside the cultured pearl. Even with the owner’s consent, however, we decided not to cut the pearl, as the imaging techniques were sufficient to prove the bead-cultured origin.

We wonder if this gem represents a single specimen achieved by a curious experimenter, or if there is now an industrialized process for cultivating such pearls. The cultivation technique used, even if it is known to produce cultured pearls in farms, requires advanced knowledge of the process. The owner reports having handled a black round pen pearl “the size of a golf ball.” From the size and symmetry and given this new discovery of a bead-cultured pen pearl, one can speculate that this too might be a bead cultured pearl.

This bead nucleation technique for unusual species could have easily been developed in the past. To our knowledge, though, this specimen represents the first non-nacreous beaded cultured pearl examined by a laboratory. Faced with the expansion of the bead culturing process and the possibility of successful trials in different mollusks, gemologists need to be very cautious in natural origin determinations, even when there is every reason to believe a pearl to be natural. Source: GIA @topic:5


Title: Chinese Freshwater Pearl Culturing, Overall Market Summary Abstract: Figure 1. Jack Lynch of Sea Hunt Pearls displays strands of baroque bead-nucleated Chinese freshwater cultured pearls at his AGTA booth. Photo by Duncan Pay/GIA.

Also at the AGTA show, Jack Lynch (Sea Hunt Pearls, San Francisco) offered his perspective as a pearl entrepreneur (figure 1). Over the years he has introduced many trends in cultured pearls and pearl culturing techniques to the market, including soufflé pearls: large baroque Chinese freshwater cultured pearls with fine luster, interesting colors, and light heft (Spring 2010 GNI, pp. 61–63, www.gia.edu/gems-gemology/spring-2010-gem-news-international).

Lynch’s reputation for introducing new products and styles leads to the same question at his Tucson booth every year: “What’s new in the pearl business?” Typically the question centers on freshwater cultured pearls from China. This year, he noted, the emphasis of Chinese pearl culturing innovation was on size. As evidence, Lynch showed us a remarkable necklace composed of round freshwater cultured pearls graduating from 15.4 to 19.3 mm (figure 2). He had never seen a necklace of this size and quality, with beautifully matched, top-quality round pearls. His supplier only had four available, and this necklace was the finest.

Figure 2. This spectacular strand of Chinese freshwater cultured pearls is graduated from 15.4 to 19.3 mm. Lynch described it as the best of four such strands available when he purchased it from his supplier. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls.
Rather than producing baroque pearls, like the soufflé, the drive is now toward bead nucleation and large, spherical pearls. As producers initially sell by weight, there is a financial imperative to produce bigger pearls.

Although producers are ultimately striving for quality, quantity is still the most important factor. Lynch felt that the goal of Chinese freshwater pearl culturing has always been the production of “large white round pearls” and that success to date has been limited, with extremely small volumes of fine-quality product available. Certainly, Lynch knows of no more than a handful of examples like the necklace he showed us at his AGTA booth.

Lynch was uncertain which kind of nuclei or culturing process is used for these larger spherical pearls, but he said the results speak for themselves. He believed it might be similar to the proprietary process used by Chinese producer Grace Pearl for its “Edison” pearls. In this method, genetically selected mussels are implanted using tiny beads instead of mollusk tissue. “Edison” is a backhanded tribute to American inventor Thomas Edison.

Lynch noted that producers are continually hybridizing the mussels used for cultivation, and that they remain very tight-lipped about their methods. Without drilling, sawing, or X-raying the pearls, it is difficult to fully understand the processes or growth methods used.

He mentioned that some of the top producers in China have become increasingly “bullish” about their products, comparing them very favorably with the best South Sea cultured pearls. Because the Chinese domestic market is so strong, its consumers are prepared to pay higher prices than consumers in countries like the U.S. The producers are, in effect, pricing their products out of these markets. According to Lynch, the message from these producers is that the traditional stature of their product vis-à-vis other pearl types must change. In the meantime, they will not consider lowering their prices to satisfy traditional export markets in the U.S. and Europe.

We noticed he had a comprehensive selection of baroque freshwater cultured pearls. Lynch said that while there is moderate market demand for baroque pearls, much of the production originates from cultivators striving for spherical pearls, because “that’s where the money is.” In his opinion, much of the current Chinese production is similar to “Kasumiga pearls” with textured skins that display very strong orient over natural colors (figure 3).

Figure 3. These 16 × 13 mm bead-nucleated baroque Chinese freshwater cultured pearls have impressive heft along with striking orient and warm natural colors. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls
Known as “ripple” pearls for their textured surface, they are highly regarded for their prismatic effects, near-metallic luster, and organic shapes. As a strand wholesales for just a few hundred dollars, they present a “big look” for a modest outlay. For example, a very rough estimate on the 15.4–19.3 mm round necklace shown in figure 2 would be $10,000 per strand, whereas these baroque multicolor necklaces cost just a few hundred dollars per strand.

Lynch’s higher-quality baroque Chinese freshwater pearls are larger and have smoother skins (figure 4), so the price rises accordingly. The next examples he showed us cost two to three times more. According to Lynch, they are very fashion-forward and still represent a tremendous value for the size.

Figure 4. These slightly larger, higher-quality baroque cultured pearls have smoother skins than those in figure 3. As a consequence, they are priced two to three times higher. Natural-color goods are in the foreground, while the white pearls have been bleached for a more uniform appearance. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls.
The higher-quality baroque strands Lynch showed us were also bead nucleated, but the bead had been positioned more conventionally, in the gonad of the mollusk. This technique produces a different type of pearl, known in the trade as a “fireball” (D. Fiske and J. Shepherd, “Continuity and change in Chinese freshwater pearl culture,” Summer 2007 G&G, pp. 138–145, www.gia.edu/gems-gemology/summer-2007-continuity-change-chinese-freshwater-pearl-culture-fiske).

All the peach to pink colors in these strands are natural, Lynch told us. Bleaching produces the white product. Unlike the soufflé pearls, which are typically hollow after being drilled, these bead-nucleated pearls have impressive heft. They sell very well, according to Lynch, and no two necklaces are uite the same due to the uniqueness of every pearl. As an aside, he told us that the weight of the pearls he shipped to the show was around 489 pounds (about 221 kg), much of that consisting of bead-nucleated freshwater cultured pearls.

Next, he showed us some tissue-nucleated (non-beaded) round freshwater cultured pearls (figure 5). These 5–6 mm spherical pearls were impressively uniform with high luster and crisp reflections from smooth skins, making them an excellent substitute for an akoya strand. Finding this sort of quality is very difficult these days, Lynch told us. These also cost a few hundred dollars per strand.

Although Lynch carries a wide stock of Chinese freshwater pearls, most of his resources go into purchasing Tahitian, South Sea, and akoya cultured pearl products. All in all, he said, supply of every top-quality cultured pearl type is very limited, and competition for available product is very high. The increase in Chinese consumption has drastically affected supply for U.S. and European wholesalers. Fortunately, Lynch told us with a sense of relief, he has been a “pearl hoarder” for many years, so he has a significant inventory to draw upon.

Figure 5. These tissue-nucleated Chinese freshwater cultured strands resemble fine akoya cultured pearls. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls.
Lynch suggested that the Chinese domestic market does not know what the market value of many products might be elsewhere. The Chinese have a different mindset than consumers in the West, he told us, citing a fashion example: “You’ll pay more for couture items in Shanghai than in Paris… If it’s expensive, it’s better.” Although many commentators insist the Chinese economy is slowing down and no longer enjoying double-digit percentage growth, Lynch said that the emergence of a large middle class that wants all the trappings of wealth is driving up the market prices for gems and pearls. He noted that the Chinese like to display their wealth, and jewelry is an obvious way to do that.

Asked what was selling this year, Lynch explained how his business has changed. He used to sell more volume at the Tucson show, especially freshwater items wholesaling for $300 to $600 apiece. Today he handles fewer transactions, but the average transaction has increased dramatically. Lynch’s perception is that spending habits have changed as the middle class in the U.S. has shrunk. He finds fewer consumers looking for $1,000 items. Instead, he sees purchasers from a higher income bracket looking for a $20,000 or $30,000 piece.

Figure 6. Fine Tahitian and South Sea cultured pearl singles and pairs are in high demand with designers for one-of-a-kind custom jewelry pieces. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls.
Lynch now sells far more round white South Sea and Tahitian goods, along with fine single pearls and pairs (figure 6). The first piece he showed us was a superb, exceptionally large round South Sea cultured pearl of 18.2 mm (figure 7). Lynch said he buys with designers in mind, as items like this are far more affordable than a strand and make excellent centerpieces for custom jewelry pieces. The price for such a piece would be approximately $6,000, whereas a necklace of this quality would cost many tens of thousands of dollars.

Figure 7. This superb spherical South Sea cultured pearl measures 18.2 mm in diameter and weighs 8.25 grams. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls.
Finally, Lynch pulled out a uniquely shaped Tahitian baroque cultured pearl (figure 8). Its flattened shape would allow it to sit especially well as a pendant. At 19.7 mm, it was large. Even though the pearl was very baroque, its color was exceptional. This piece had the style and substance to really make a statement at a reasonable price (a couple of thousand dollars).

Figure 8. This 19.7 mm Tahitian Sea cultured pearl weighs 2.45 momme (9.19 grams). It would make a fine centerpiece for an item of custom jewelry. Photo by Duncan Pay/GIA; courtesy of Sea Hunt Pearls. Source: GIA @topic:5


Title: Atypical Bead-Cultured Pearls with Unusual Nacre Growth Abstract: Figure 1. The 10 loose pearls submitted for identification. Samples 1, 4, and 5 are conventional bead-cultured pearls, while the rest were cultured with atypical nuclei. Photo by Sood Oil (Judy) Chia, courtesy of Aloha Pearls.

Atypical bead-cultured pearls are, by definition, cultured with unconventional beads as opposed to the typical round, predominantly freshwater shell beads. Examples of such atypical bead nuclei are irregularly shaped pieces of shell, ceramic, plastic, wax, coral beads, or even cultured or natural pearls.

Recently, GIA’s New York laboratory received 10 loose undrilled pearls for identification. These samples exhibited a brownish bodycolor and measured from 7.17 × 6.92 × 6.42 mm to 12.25 × 9.72 × 9.28 mm (figure 1). Many were unusually lightweight for their size. Microradiographic examination of seven of the pearls revealed atypical bead nuclei (figure 2). The X-ray transparencies of the bead nuclei allowed us to observe faint demarcations and drill holes with varying degrees of clarity in the nuclei.

Figure 2. Microradiographs of seven pearls revealed atypical beads that were transparent to X-rays. The beads showed faint demarcations and drill holes of varying clarity. Unusual nacre growth that partially filled the drill hole of the bead of one pearl is seen in image C.
These atypical bead nuclei permitted some unusual nacre growth to develop within the drill holes, as shown in figure 2C, where the nacre secretion flows into the drill hole. This interesting observation concerning nacre viscosity was also described in recent work on atypical bead culturing experiments (K. Scarratt et al., “Atypical ‘beading’ in the production of cultured pearls from Australian Pinctada maxima,” GIA Research & News, Feb. 13, 2017).

To better visualize the unusual nacre growth within the drill hole of the bead in one of the pearls, we used computed X-ray microtomography (μ-CT) and subsequently reconstructed the pearl using computer software (figure 3). The reconstructed image displayed a surface indentation aligned with the bead’s drill hole (shown in orange in figure 3, left). Additional nacre growth (shown in green, figure 3, right) filled about half of the drill hole. The yellowish outer region in figure 3 (left) represents the outer nacre of the pearl.

Figure 3. Left: A computed 3-D reconstruction of one of the atypical bead-cultured pearls. The orange area represents the transparent bead revealed by X-rays, with a drill hole partially filled by nacre growth shown by the whitish area (indicated by the arrow). A surface indentation toward the top also corresponds to the orientation of the bead’s drill hole. Right: Reconstruction of the internal bead only. The central pink area is the drill hole inside the bead nucleus. The green area represents the nacre growth that formed inside the drill hole. Photos by Emiko Yawaza.
Although this is not the first time GIA has received pearls cultured using X-ray transparent bead nuclei (Fall 2011 Lab Notes, pp. 229–230), the unusual nacre growth pattern within some of the drill holes in this sample group is worthy of note. Three-dimensional rendering using computer software and μ-CT data sets also proved very useful in visualizing the internal structure, further demonstrating the technique’s worth as a powerful tool in pearl identification. Source: GIA @topic:5


Title: Studies on Tourmaline, Sapphire, Cultured Pearl, and a Reliquary of Legend… Abstract: Spring is always a time of renewal. For our industry, early February marks the Tucson gem shows, the first big event of the season, where buyers are tempted with colored gems of every type and price. Similarly, there is truly something for everyone in our Spring 2019 edition.
We begin with multicolored tourmalines; few gems encompass such a rich variety of colors. In our lead article, GIA’s Ziyin Sun, Aaron Palke, and Christopher Breeding join Louisiana State University’s Barbara Dutrow to present a simplified classification system for tourmaline species using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analysis of major trace elements.

“A simplified classification system for tourmaline species using LA-ICP-MS……”

Our second study unites researchers based in Switzerland, Bahrain, and Scotland. Age dating of sulfide inclusions in diamonds using radiogenic decay systems is well known, but for gemologists, applying similar analyses to zircon inclusions in corundum is an emerging practice. Lead author Emilie Elmaleh tells us more about the age and origin of sapphires from two Sri Lankan alluvial deposits.
Next, a team headed by Gerard Panczer of France’s Claude Bernard University Lyon 1 contributes the first scientific, gemological analysis of the fascinating Talisman of Charlemagne. This historical, bejeweled container of holy relics—or reliquary—is a rare masterpiece of the goldsmith’s art dating back to the ninth century.
The authors of our fourth paper use a combination of LA-ICP-MS and multivariate analysis to compare the trace-element concentrations of two groups of cultured freshwater pearls (one from China, one from the United States) with natural pearls found in the U.S. This study, by Artitaya Homkrajae and her GIA team, provides the prospect of greater confidence identifying pearls of freshwater origin.
In our fifth paper, regular contributor Karl Schmetzer investigates the color appearance of faceted alexandrite, where the quest for the best color change is complicated by this biaxial gem’s inherent pleochroism. Through direct observation of synthetic alexandrite samples, he documents the impact of the inevitable multiple internal reflections on placement of a faceted gem’s table facet and its perceived color change and pleochroism.
Our final paper is a field report on Ethiopia, a new land of opportunity for colored gems. The 2016 discovery of fine emerald at Shakiso in the southern part of the country, coupled with the 2017 news of sapphires from northern Tigray Province, prompted a 2018 GIA field expedition. Led by field gemologist Wim Vertriest, the group documented mining and processing, measured social impact, and collected samples for GIA’s reference collection.
Our regular columns also provide plenty of interest. Our Lab Notes section features the largest diamond ever discovered in North America, Burmese color-change sapphire, and a synthetic diamond containing a CVD layer grown on natural diamond. In Diamonds from the Deep, Karen Smit and Steven Shirey examine fundamental questions around the ages of natural diamonds and the lessons we can draw from this information, while Micro-World offers a glimpse into the internal world of condor agate from Argentina, grandidierite inclusions in sapphire, and a fossil insect in opal. Our Gem News International section has more than 30 pages covering the 2019 Tucson shows, blending market insights with a fascinating display of gems from around the world.
As is customary, this issue contains the annual G&G Challenge: We invite you to test your gemological knowledge and skills of recall in the 2019 quiz. Finally, congratulations to our 2018 Dr. Edward J. Gübelin Most Valuable Article Award winners.
Welcome to the 2019 Spring edition of Gems & Gemology! Source: GIA @topic:7


Title: Cultured Abalone Blister Pearls from New Zealand Abstract: The successful culturing of abalone pearls has been known since French scientist Louis Boutan’s experimentation in the late 1890s, but commercial production has been achieved only in recent decades. The use of New Zealand’s Haliotis iris, with its colorful and iridescent nacre, has had the strongest recent impact on this industry. Empress Abalone Ltd. is producing large, attractive cultured blister pearls in H. iris. The first commercial harvest in 1997 yielded approximately 6,000 jewelry-quality cultured blister pearls, 9–20
mm in diameter, with vibrant blue, green, purple, and pink hues. Examination of 22 samples of this material by standard gemological and advanced testing methods revealed that the presence and thicknesses of the conchiolin layers had a significant impact on face-up appearance. Empress Abalone Ltd. is also experimenting with producing whole free-formed cultured pearls in this gastropod mollusk. Source: GIA @topic:5


Title: Freshwater Natural Pearls from the Concho River, Texas Abstract: Figure 1. Nine “Concho” pearls examined in this study together with a Tampico pearlymussel shell. The shell measures approximately 12 × 8 cm. Pearls range from 0.12 to 16.59 cts. Photo by Sood Oil (Judy) Chia.

Throughout history, natural pearls have been found in many species of freshwater mollusk in North American lakes and rivers. They are most abundant within the Mississippi River drainage basin, which provides the perfect habitat for these animals because of the large watershed areas with their underlying limestone substrata (J.L. Sweaney and J.R. Latendresse, “Freshwater pearls of North America,” Fall 1984 G&G, pp. 125–140). Lesser-known sources of natural freshwater pearls are the Colorado River and Brazos River and their tributaries in the state of Texas. However, the best samples are sometimes found in a species named Tampico Pearlymussel (Cyrtonaias tampicoensis) that inhabits the Concho River in West Texas.

The mollusk is distributed from northeastern Mexico into the Concho, Colorado, and Brazos Rivers of central Texas and has been collected by licensed harvesters. Mussel harvesting is restricted to hand collection only, and there is a legal minimum shell size requirement. In addition, several areas in Texas have been designated mussel sanctuaries in order to provide protection and species conservation (R.G. Howells, “The Tampico pearlymussel (Cyrtonaias tampicoensis), shades of the Old West”). Pearlers find mussels by wading into water that is three to four feet deep and feeling for the shells with their toes. Rattlesnakes on the banks and water moccasins and snapping turtles in the murky water (J. Morthland, “Irregular radiance: The rare beauty of Conch River pearls,” Texas Highways, April 2015) pose risks to these adventurers searching for gems.

GIA’s New York laboratory recently received nine loose pearls from Stone Group Laboratories (Jefferson City, Missouri) for a joint study. The pearls ranged in size from 2.95 × 2.45 mm to 14.76 × 13.55 × 13.13 mm. Reportedly recovered from Tampico pearlymussel shells taken from the Concho River, they exhibited colors ranging from purplish pink to orangy pink. Some of the samples also possessed varying degrees of a brownish hue (figure 1). Most of the small pearls in the group exhibited a dull chalky appearance, with some broken or cracked areas of the nacreous surface. The largest pearl in the group (16.59 ct) showed good nacre condition, a high luster, and noticeable orient on its surface.

Figure 2. The pearls’ internal structures showed typical natural concentric growth arcs, while some also exhibited dark organic-rich centers and natural internal cracks.
The internal structures of the pearls were analyzed by real-time microradiography, and the majority revealed typical concentric natural growth arcs (figure 2). Dark organic-rich centers were also seen in some of the pearls, as well as internal fissures, cracks, or growth boundaries. There were no indications of bead nuclei or non-bead cultured features (irregular linear or void structures). Additional advanced techniques such as X-ray fluorescence imaging and energy-dispersive X-ray fluorescence (EDXRF) spectrometry revealed noticeable X-ray luminescence and high manganese content, confirming the pearls’ freshwater origin. Furthermore, Raman spectroscopic analysis of all the pearls detected polyacetylenic compounds (figure 3); these are natural pigments responsible for the colors of many freshwater and some saltwater pearls.

Figure 3. Raman spectrum of a “Concho” pearl showing polyacetylenic pigment-related peaks at 1130 and 1516 cm–1 and peaks at 1086, 704, and 701 cm–1 (the latter two a doublet) of structural calcium carbonate in the form of aragonite.
The study provided GIA with a rare opportunity to study this unique group of freshwater natural pearls originating from the southwestern United States. Both gemological and analytical data were consistent with their claimed natural and freshwater origin. Pearls produced from this locality often possess beautiful fancy pink, purple, or lavender colors (Summer 1989 GNI, p. 115; Fall 2005 Lab Notes, pp. 259–260), as demonstrated by these examples. Source: GIA @topic:5


Title: Data Supplement Abstract: The published versions of the authors’ microradiographs are shown here, with the original versions below them.

Figure S3. Microradiographs of sample 8, a bead-cultured saltwater pearl from Pinctada
fucata, produced with an FPD (top) and an II (bottom). The diameter of the bead is
about 4.5 mm.

Figure S4. Microradiographs of the center of sample 19 (a non-bead-cultured saltwater
pearl from Pinctada maxima), produced with an FPD (top) and an II (bottom); fields of
view approximately 7 mm.

Figure S5. Microradiographs of sample 1 (a natural saltwater pearl from Pinctada
radiata), produced with an FPD (top) and an II (bottom); fields of view approximately
3.5 mm.

Figure S6. Microradiographs of sample 21 (a non-bead-cultured freshwater pearl from
Hyriopsis species), produced with an FPD (top) and an II (bottom); fields of view
approximately 9 mm. Source: GIA @topic:5


Title: Paspaley: Inside an Exclusive South Sea Pearl Auction Abstract: View Gallery

The first stop for nearly all saltwater cultured pearls on their way to market is the producer auction. Three or four times each year, the producers of South Sea and French Polynesian black cultured pearls auction their harvests in Hong Kong. Akoyas are auctioned in Kobe, Japan.

In mid-September 2012, I visited the auction held by Paspaley, the largest producer of South Sea cultured pearls, to see exactly how these sales work. Such auctions are normally by invitation only, so it was a rare glimpse inside this part of the pearl world.

The harvest was divided into several dozen lots, based on quality factors; size, shape (roundness), luster and color. Most of the lots carried reserve prices, given in Japanese yen, total weight in momme (1 momme = 3.75 grams) and a quality designation (AAA, AA, etc.). Paspaley’s people matched some of the top-quality pieces into strands, several of which had undisclosed reserve prices.

During the one-day auction, invited dealers were given fifteen minutes to examine each lot on which they planned to bid. Those who wanted a very close look could leave a place card on the auction display and carry the lot to a back table—Paspaley’s staff was quite adamant about the fifteen-minute rule. After looking over the goods, the dealers completed bid forms, which they left in the “ballot box” at the end of the display table.

All of the bidders were pearl wholesalers from the U.S., China, Japan and Europe. The September auction, which included golden cultured pearls from producers in the Philippines, is typically the smallest of the company’s quarterly sales.

Pearl producers developed the auction system about thirty years ago because it was the most efficient way of getting goods to market and determining prices. Before then, Paspaley and others sold their production to the Japanese wholesalers who once dominated the market. Source: GIA @topic:5


Title: Cultured Pearl Farming and Production in the Federated States of Micronesia Abstract: The current production of cultured pearls from the black-lipped pearl oyster (Pinctada margaritifera) in the Federated States of Micronesia (FSM) includes mostly beaded as well as blister and nonbead-cultured pearls in a wide array of colors. Pearl farming is carried out on four islands, with plans for commercial production in the near future. The sector is envisaged as a model for economic development and marine conservation. To successfully compete in the marketplace, pearl farmers in the FSM should focus on producing high-quality cultured pearls and explore market differentiation strategies such as the “Micronesian Blue” product. Gemologically, the FSM cultured pearls are indistinguishable from those of French Polynesia that are produced using the same mollusk species. Source: GIA @topic:5


Title: Paspaley Pearl Auction Shows Signs of Market Revival Abstract: Buyers at the 53rd Paspaley Pearl Auction at the Hong Kong Convention Centre examine lots of white South Sea and golden pearls. Buyers place written bids for each lot in a sealed box that is opened at the close of the three-day sale. Photo by Russell Shor/GIA

                      The market for cultured saltwater pearls has softened this year as growth in Chinese demand has slowed, according to dealers at the recent September Hong Kong Gem and Jewellery Fair.

Demand from China had pushed prices up some 30% in the previous two years, while expenses remained relatively flat, so dealers noted that they could weather the corrections in the market.

Demand for Akoya, white and gold South Sea pearls, and Tahitian black pearls was down several percentage points through the first half of the year. Prices and demand were starting to “edge upward” at the Paspaley Pearling Company Hong Kong auction, however, said the company officials who oversaw the sale.

	A single lot of 519 South Sea cultured pearls weighing 448.6 momme (1 momme = 3.75 grams) offered at the September Paspaley Pearl Auction in Hong Kong. Photo by Russell Shor/GIA
The company invited 141 pearl dealers – regular clients – to the annual three-day, invitation-only auction. Officials said 110 from Japan, China, the U.S. and Europe registered by the middle of the second day, and more were expected, which they said was good sign for the fall.

Producers such as Paspaley, whose main output is high-end white South Sea goods, sell most of their productions at such auctions. The goods are separated into lots according to size, weight and quality, including shape, color, luster and orient.

Because the Japanese Yen is the dominant currency for the industry – tracing back to the period when that country was the only major pearl culturing center – it is how reserve prices are given.

	Lots of golden South Sea pearls produced in the Philippines were divided into various sizes, shapes and colors. Photo by Russell Shor/GIA
Paspaley’s offerings included white goods from the company’s farm in Northern Australia, contract producers in Indonesia and golden cultured pearls from a farm in the Philippines, which the company owns with Japanese and Chinese partners.

Pearl dealers agreed with Paspaley that the market had grown increasingly dependent on China in the past four years as demand for higher-end pearls grew very slowly or not at all in Japan and Western countries. In addition, competition is increasing from Chinese freshwater pearls, which are continually improving in quality and variety. Source: GIA @topic:15


Title: Assembled Cultured Blister Pearl with an Unusual Component Abstract: Figure 1. This blue-violet assembled cultured blister pearl (mabe) weighed 2.44 carats and measured 10.23 × 5.86 mm. Photo by Lhapsin Nillapat.

	GIA’s Bangkok laboratory recently examined a blue-violet assembled cultured blister pearl (mabe) weighing 2.44 ct and measuring 10.23 × 5.86 mm (figure 1). The specimen had the appearance of a typical mabe pearl, exhibiting a boundary line between the nacre face and shell base. 2D microradiography showed a component with an unusual fluted shape, with radio-translucency similar to that of the CaCO3 nacre and the shell (figure 2).

Figure 2. A microradiograph of the intact assembled cultured blister pearl prior to sawing revealed an internal component. The radio-translucency of the object, the nacre, and the shell base are similar. Image by Areeya Manustrong.

	GIA has examined the characteristics of mabe pearls used in commercial jewelry over the years (see Lab Notes: Summer 1981, pp. 104–105; Summer 1991, pp. 111–112; Fall 1991, p. 177; Summer 1992, pp. 126–127; Fall 1992, pp. 195–196; Fall 1996, p. 210), but none of these notes mentioned this unusual component. In Bangkok, this feature has been seen five times in mabe pearls submitted for testing since 2010; questions about its identity and purpose have been raised since the first observation.

	Out of curiosity, one client decided to cut their sample in half in order to examine the interior in more detail (figure 3, left). The two halves consisted of a thin nacre dome top, which was coated with a dark layer on the inner surface; an artificial resinous material; and the white fluted object bordering the shell base. The fluted object was translucent, and a clear spiderweb structure was visible at 10× magnification. When exposed to standard short-wave UV radiation (254 nm) and examined in the DiamondView, this object showed a moderate white blue reaction that followed the spiderweb pattern (figure 3, right).

Figure 3. Left: The cross-section revealed the white fluted object with a spiderweb structure bordering the shell base. Photo by Sasithorn Engniwat. Right: DiamondView imaging showed a moderate white blue reaction following the spiderweb pattern. DiamondView image by Artitaya Homkrajae.

	Further investigation with Raman spectroscopy using a 488 nm laser revealed a calcite spectrum with peaks at 159, 285, 716, 1088, and 1750 cm–1, similar to white coral (Corallium secundum). A small peak related to carotenoid pigments was present at 1020 cm–1 (e.g., J. Urmos et al., “Characterization of some biogenic carbonates with Raman spectroscopy,” American Mineralogist, Vol. 76, 1991, pp. 641–646).

	Based on the spiderweb structure, radio-translucency, calcite spectrum, and general appearance, the object appeared to be a biogenic carbonate. White coral was the first material considered. Further research revealed accounts of sea urchin sections used in some assembled cultured blister pearls from Bali, Indonesia, in “Kuta” pearls (E. Strack, Pearls, Ruhle-Diebener-Verlag, Stuttgart, Germany, 2006, p. 605). Regardless of identity, the reason for including this material within some mabe pearls remains uncertain. It does not appear related to either the formation of the mabe pearl component or its weight and stability. Source: GIA @topic:5


Title: Continuity and Change in Chinese Freshwater Pearl Culture Abstract: The great majority of Chinese freshwater cultured pearls are produced by implanting tissue pieces in the mantle of Hyriopsis cumingii mussels. Farmers have experimented with bead nucleation, but until recently the methods tried did not produce the quantity or quality necessary for economic success. In the late 1990s, Chinese researchers imported H. schlegelii mussels from Japan, began propagating them in hatcheries, and started cross-breeding them with native H. cumingii mussels. Using the two pure species and the hybrid, Chinese farmers produce tissue implantation-only cultured pearls and have developed a method called coin-bead/spherical-bead nucleation. This method has yielded significant quantities of jewelry-quality baroque shapes and lesser quantities of jewelry-quality rounds and near-rounds. Continued experimentation is expected to increase the percentage of rounds and near-rounds. Source: GIA @topic:5


Title: Seattle Gemologists Import Pearls, Build Family Legacy Abstract: The Oba family – from left, Avery, Jessica, Yoshizumi and Amadea – is building its legacy in pearls. Courtesy Oba Family

                      Countless finished pieces traded hands at this year’s Tucson gem and mineral shows; among them were a handful of pearl and gemstone bead necklaces fashioned by an up-and-coming designer from Seattle: 6-year-old Amadea Oba.

Oba was arguably the youngest entrepreneur at the shows, but her 3-year-old brother, Avery, is hot on her heels. He’s already learning to shake pearls through sieves to sort them by millimeter size, say the pair’s parents, Yoshizumi “Yoshi” and Jessica Oba.

The elder Obas, owners of pearl importer Y.K. Trading, both graduated from GIA’s Santa Monica campus with Graduate Gemologist diplomas in November 1995.

Though the pair was originally scheduled to have different start dates, timelines changed and they ended up in the same classroom. Jessica Oba recalls meeting a polite young Japanese man her first day; her now-husband jokes that he knew right away they would be a good fit.

“Jessica was the best student in the class and I was the worst, so I knew I had to grab her,” Oba says. “I wasn’t really planning to meet my future wife at GIA – it must have been fate.”

Yoshi Oba grew up surrounded by the pearl industry in his hometown of Kobe, Japan. His father owned a pearl company, and Oba remembers hearing his father’s colleagues talk about GIA. Even as a young man, he says he noticed the respect a Graduate Gemologist diploma commanded among those in the industry.

Oba decided as a teenager that he would one day move to the United States and open his own business. He knew pearls, but wanted to learn more about other gemstones and other aspects of the jewelry industry. His first order of business was to learn English, so in 1990, Oba left Japan for his “adopted hometown” of Seattle, Washington.

Jessica Oba – lacking any family connection to the jewelry industry – had a lifelong interest in gems. Her first job, as a high school student in Oxnard, California, was working at a gift boutique that specialized in sterling silver and gemstone jewelry. Her curiosity was further piqued by the experience, and when an attentive manager handed her a GIA brochure, she enrolled in the Institute’s distance education courses.

Jessica Oba used her earnings from her high school retail job to continue coursework through her first post-graduation job with a fine jewelry store in nearby Camarillo, California.

“The correspondence work was satisfying and rewarding,” she says, “but I really longed to have the on-campus experience.”

So she moved to Santa Monica in May 1995 – where she met her future husband and business partner.

The couple moved to Seattle immediately after graduation in 1996. Yoshi Oba founded Y.K. Trading, and Jessica Oba accepted a job offer with a colored stone wholesaler. They married two years later, and Jessica Oba came on board to help build the family business.

Today, Y.K. Trading imports from Japan, China and Tahiti, and carries several types of pearls, including Japanese Akoya, Chinese freshwater, Tahitian and South Sea. Their primary customers are other small businesses, such as independent jewelry stores, designers and wholesale repair shops. They sometimes do specialty contract work – Jessica Oba strings pearls for other dealers, while Yoshi Oba drills and sorts large lots for other companies.

Their business works with a true international community, so Jessica Oba says their GIA experience comes into play regularly.

“The skills you learn at GIA are invaluable,” she says. “It provides a bit of shorthand when meeting other graduates – you instantly know there is this shared well of knowledge, and that increases your confidence when dealing with colleagues and clients.”

If their children’s early interest in the family business is any indication, the Obas may soon be using that gemological “shorthand” at home.

	Yoshi and Jessica Oba use their GG skills to help them in their pearl importing
	business, Y.K. Trading. Photo by Siegfried Markwart, courtesy Y.K. Trading Source: GIA @topic:11


Title: A Large Baroque Tridacna Gigas (Giant Clam) Pearl Abstract: Figure 1. This giant clam pearl was recovered from a huge Tridacna gigas mollusk in Papua New Guinea. Photo by Lai Tai-An Gem Lab.

              Natural pearls from various clam species are not as rare as many believe, and plenty of samples are available in the market. But with the exception of a few very large specimens, they tend to occur in sizes under 20 carats. A client of the Lai Tai-An Gem Lab in Taipei recently requested a report on what he claimed was a natural clam pearl (figure 1) recovered from a huge Tridacna gigas mollusk from a fishery in Papua New Guinea in 1981.

The pearl exhibited an elongated baroque shape with uneven brown and white coloration, lacking the lustrous and shimmering iridescent colors of a nacreous pearl. It weighed 360.59 ct and measured 76.7 × 28.0 × 25.8 mm. We also recorded an SG of 2.88, which fell within the range of other Tridacna pearls examined in our laboratory. Long-wave UV produced a moderate chalky blue reaction. FTIR, Raman, and UV-visible spectra were collected. The Raman spectrum clearly showed that the pearl was composed of aragonite, given the peaks at approximately 142, 199, 701, and 1082 cm–1. FTIR reflectance spectra also revealed calcium carbonate in the form of aragonite, with peaks at approximately 873 and 1483 cm–1.

Figure 2. The natural Tridacna pearl showed a characteristic sugary surface texture. Photo by Lai Tai-An Gem Lab; magnified 60×.
While microradiography is usually applied to the identification of pearls, it is considered especially beneficial when various types of nacreous pearls need to be separated from one another. It is usually less helpful with non-nacreous or non-porcelaneous pearls such as this one, since many reveal little in the way of helpful structure. Observed through the loupe and microscope, the pearl showed the grainy or sugary surface texture (figure 2) typical of some natural Tridacna pearls. This example was noteworthy for its size and interesting coloration, and its pronounced banding when viewed with transmitted light (figure 3), a feature that is often considered indicative of shell fashioned into imitation pearls. This Tridacna pearl was clearly no imitation.

Figure 3. The Tridacna pearl exhibited pronounced banding when viewed with transmitted light. Photo by Lai Tai-An Gem Lab. Source: GIA @topic:5


Title: The Current Status of Chinese Freshwater Cultured Pearls Abstract: Chinese freshwater cultured pearls (FWCPs) are assuming a growing role at major gem and jewelry fairs, and in the market at large. Yet, it is difficult to obtain hard information on such topics as quantities produced, in what qualities, and the culturing techniques used because pearl culturing in China covers such a broad area, with thousands of individual farms, and a variety of culturing techniques are used. This article reports on recent visits by two of the authors (SA and LTZ) to Chinese pearl farms in Hanzhou Province to investigate the latest pearl-culturing techniques being used there, both in tissue nucleation and, much less commonly, bead (typically shell but also wax) nucleation. With improved techniques, using younger Hyriopsis Cumingi mussels, pearl culturers are producing freshwater cultured pearls in a variety of attractive colors that are larger, rounder, and with better luster. Tissue-nucleated FWCPs can be separated from natural and bead-nucleated cultured pearls with X-radiography. Source: GIA @topic:5


Title: Fall 2017 G&G: HPHT Synthetic Diamond Review, Radiocarbon Dating of Pearls from the New World, and Colombia’s Evolving Emerald Industry Abstract: While the size and color of synthetic diamonds grown by the high-pressure, high-temperature (HPHT) method have
changed considerably in the past decade, a combination of gemological characteristics, spectroscopic features, and
UV fluorescence reactions provides reliable indication of synthetic origin. Our lead article surveys the HPHT-grown
diamonds seen in GIA labs since 2007. The HPHT synthetics on the cover, part of the GIA collection and ranging in
weight from 0.31 to 1.94 ct, demonstrate the colors now seen in this lab-grown material. Photo by Kevin Schumacher.

The Fall 2017 issue of Gems & Gemology covers topics across the gemological spectrum, from HPHT synthetic diamond identification criteria to natural saltwater pearls harvested during the Columbian era and the current state of Colombia’s emerald industry. Other highlights include a study of photoluminescence spectra in emerald as a method of determining geographic origin, a review of synthetic star corundum from mid-twentieth century Germany, and an examination of the material known in the industry as “dalmatian jasper.”
OBSERVATIONS ON HPHT-GROWN SYNTHETIC DIAMONDS: A REVIEW

While some HPHT synthetic inclusions appear transparent, most appear to be pieces of dark solidified metal flux. A variety of shapes are possible, including thin rods and irregular shapes, and some are associated with feathers. These metallic inclusions can create a magnetic attraction. Photo by Sally Eaton-Magaña.
While synthetic diamonds grown by the high-pressure, high-temperature (HPHT) method have been commercially available since the mid-1990s, the technology has made great strides in the last decade. In the issue’s lead article, GIA’s Sally Eaton-Magaña, James E. Shigley, and Christopher M. Breeding provide insight into the HPHT-grown material available on the market, including statistical data about the cut, color, and clarities available as well as identification criteria for gemologists.
SALTWATER PEARLS FROM THE PRE- TO EARLY COLUMBIAN ERA: A GEMOLOGICAL AND RADIOCARBON DATING STUDY

These natural pearls, reportedly from the pre- to early Columbian era, represent some of the 85 samples examined in the study. They were discovered already drilled but were only recently strung as a necklace. The center blister pearl (31.41 × 16.86 × 10.25 mm) consists of multiple small pearls that formed as an aggregate. Photo by Sood Oil (Judy) Chia.
Pearls were treasured by the indigenous people of the Americas and by the Spanish colonists. Oyster beds in the Caribbean were heavily exploited during the first half of the sixteenth century before oysters became scarce. A supplier came into possession of 85 pearls, reportedly from Central or South America and dating from the pre- or early Columbian era. A team from GIA and the Gübelin Gem Lab, led by Chunhui Zhou, analyzes the pearls through a variety of methods to validate these claims.
PHOTOLUMINESCENCE SPECTRA OF EMERALDS FROM COLOMBIA, AFGHANISTAN, AND ZAMBIA

Emerald crystals from Zambia (left), Colombia (top right), and Afghanistan (bottom right). Each emerald’s hexagonal prismatic crystal habit has been enhanced by polishing flat the two hexagonal end faces (perpendicular to the crystal’s c-axis) and two or more prism sides (parallel to the c-axis). Photo by D.B. Thompson.
Photoluminescence (PL) in emerald arises from trace chromium impurities. An emerald’s PL spectrum displays two features that can vary depending on the stone’s origin. Lead author David Brian Thompson and his team examine the PL spectra of 48 emeralds from Colombia, Afghanistan, and Zambia to provide evidence for or against possible geographic origins.
SYNTHETIC STAR SAPPHIRES AND RUBIES PRODUCED BY WIEDE’S CARBIDWERK, FREYUNG, GERMANY

Three synthetic blue star sapphire cabochons and one synthetic star ruby cabochon in direct sunlight. The ruby weighs 8.92 ct and measures 13.2 × 11.0 mm; the sapphire at the bottom left weighs 3.67 ct and measures 9.1 mm in diameter. Photos by K. Schmetzer.
During the 1950s, Wiede’s Carbidwerk patented a method of growing star synthetic corundum for the commercial market. The company sold these goods through the late 1970s, though the samples from the 1960s and beyond differ slightly from their earlier counterparts. Karl Schmetzer and his coauthors explore the variant of the Verneuil process that Wiede’s used to grow these synthetics.
TRUE COLORS OF “DALMATIAN JASPER”

Dalmatian stone samples examined in this study reveal a spotted appearance connected with the presence of alkali amphiboles disseminated through feldspar-quartz matrices. Left: A rough block-shaped specimen measuring 1.5 × 1.5 × 1 cm. Right: A polished bracelet (1 cm bead diameter) alongside a pendant measuring 3 cm in length. Photos by Tomasz Powolny.
The decorative gemstone known in the trade as “dalmatian jasper” due to its black spots (identified as arfvedsonite) is not widely discussed in the published literature. Tomas Powolny and Magdalena Dumańska-Słowik investigate the stone’s mineralogical composition and properties. On the basis of the study, they suggest the use of “dalmatian stone,” as the material does not meet the gemological definition of jasper.
THE COLOMBIAN EMERALD INDUSTRY: WINDS OF CHANGE

Colombian emerald-producing areas such as Muzo have a long tradition of independent mining. The hope of finding the stone that will change their lives is a strong motivator for miners, but bringing them into a formal system is challenging. Photo by Andrew Lucas.
Emerald mining in Colombia dates back more than a thousand years. Yet its greatest opportunities may still lie ahead, as multinational companies invest in the industry as transparency and traceability come to the forefront. In this field report, an expedition led by Colombian gemologist Darwin Fortaleché documents the recent changes in the country’s mine-to-market emerald industry.
LAB NOTES

This dark reflective platinum platelet observed in the pink synthetic sapphire is a common inclusion in flux-grown synthetic corundum. Photo by Nathan Renfro; field of view 1.82 mm.
Updates from GIA’s labs include reports on a flux-grown pink synthetic sapphire with unusual inclusions, synthetic overgrowth on a flux-heated ruby and a beryllium-diffused sapphire, and separation of synthetic melee from natural diamond using GIA’s iD100 screening device.
MICRO-WORLD

Reminiscent of a flower in a rainstorm, this inclusion scene has been dramatically enhanced using modified Rheinberg illumination to accentuate a growth blockage and thin-film rosette within a sapphire from Elahera, Sri Lanka. Photomicrograph by Jonathan Muyal; field of view 1.34 mm.
G&G’s photomicrography section features a flower-like inclusion in a Sri Lankan sapphire, silvery rutile inclusions in quartz, and fluorite hosting eye-visible barite inclusions.
GEM NEWS INTERNATIONAL

These sapphires (0.64–8.27 ct) are from Antang and Gombe, in northern Nigeria. Photo by Shunsuke Nagai.
The Fall GNI section includes an update on Mozambique ruby mining, an analysis of blue-green pyrope-spessartine with high vanadium, and an examination of sapphires reportedly from new sources in northern Nigeria. Source: GIA @topic:4


Title: Dyed Yellow Beaded Freshwater Cultured Pearls Imitating South Sea Cultured Pearls Abstract: Figure 1. Uneven color and blemishes on the surface of a low-quality dyed cultured freshwater pearl necklace obtained from Grace Pearls. Photo by Lore Kiefert.

In the spring of 2017, the Gübelin Gem Lab received a yellow pearl necklace for testing. The size and color of the specimens implied that they were South Sea cultured pearls. The high insurance value appeared to confirm this; however, there were some suspicious color patches that suggested the material had been dyed.

Only a few months earlier, author LK visited the Hong Kong office of Grace Pearls, a large producer with a pearl farm and factory in China, to see their latest batch of freshwater cultured pearls. Grace Pearls developed a proprietary method to grow large freshwater pearls with bead, marketed as “Edison” pearls. These occur in all the known colors of traditional freshwater pearls, typically white, orange, pink, and purple. To  complement their color range, they also offer yellow and black treated pearls ranging from approximately 12 to 18 mm.

The goods we saw at Grace Pearls had a wide range of qualities and prices. The lowest price for a strand of Edison pearls was approximately US$100, while the highest-quality yellow dyed pearls go for as much as US$2,000. Prices for top-quality white and pink natural-color pearls may reach up to US$40,000 per strand.

The Gübelin Gem Lab acquired from Grace Pearls a necklace of yellow dyed freshwater bead-cultured pearls to complement our extensive reference collection. The largest of these pearls measured nearly 17 mm. For study purposes, we deliberately chose a low-quality necklace showing color concentrations, slightly irregular colors from pearl to pearl, and slight blemishes on the surface (figure 1).

The grafting process, which Grace Pearls considers a proprietary method, appears to be similar to that of “Kasumigaura pearls” from Japan and “Ming pearls” from China, where the bead is drilled first and a tissue is partly inserted into the drill hole in order to introduce both tissue and bead at the same time during the implantation procedure (H.A. Hänni, “Ming pearls: A new type of cultured pearl from China,” Journal of the  Gemmological Association of Hong Kong, Vol. 32, 2011, pp. 23–24). X-ray images  clearly show drill holes in the beads of several of these cultured pearls, mostly in the  smaller beads (figure 2), while larger beads, like the one in the center of figure 1, have only one drill hole. This may be due to a possible re-implantation into the pearl sac once the first pearl has been harvested. X-ray fluorescence (XRF) analysis gave Mn and Sr values consistent with those of freshwater pearls.

Figure 2. X-ray image of yellow dyed freshwater cultured pearls. The beads range
from approximately 10 to15 mm in diameter, while nacre thickness varies from
<0.2 to >5 mm. Some of the beads show an additional drill hole. Image by Pierre
Hardy.
Upon testing, the necklace submitted by the client showed identical properties: dark yellow color concentrations around drill holes and in cavities, uneven surfaces with various shades of yellow (figure 3, left; see also C. Zhou et al., “Update on the identification of dye treatment in yellow or ‘golden’ cultured pearls,” Winter 2012 G&G, pp. 284–291), X-rays showing an additional drill hole through the bead in some of the pearls (figure 3, right), and the chemical composition of freshwater pearls (figure 4). This demonstrates the importance of staying informed on new developments in the market.

Figure 3. Left: Blemishes and dark color concentrations in cavities on the surface of dyed cultured freshwater pearls in a client-submitted necklace. Photo by Lore Kiefert. Right: An X-ray image of two pearls from the client necklace showing a clear bead. The left pearl displays an additional drill hole in the bead. Image by Pierre Hardy.

Figure 4. A plot showing the theoretical distribution of MnO vs. SrO in freshwater
and saltwater pearls (after W. Gutmannsbauer and H.A. Hänni, “Structural and
chemical investigations on shells and pearls of nacre forming salt- and fresh-water
bivalve molluscs,” Journal of Gemmology, Vol. 24, No. 4, 1994, pp. 241–252).
The red dots represent values for our reference collection necklace, the yellow
dots the values for the client-submitted necklace. Source: GIA @topic:5


Title: Atypical Bead Cultured Pinctada maxima Pearls Nucleated with Freshwater Non-Bead Cultured Pearls Abstract: The 12 white and “golden” South Sea cultured pearls (Pinctada maxima) of various shapes and sizes examined in this study. Although their external appearances are similar to saltwater bead and non-bead cultured (NBC) pearls, 11 of them are atypical bead cultured (aBC) pearls formed by inserting freshwater non-bead cultured pearls as nuclei into saltwater hosts. Photo by Nuttapol Kitdee.

White and yellow “golden” South Sea cultured pearls are typically nucleated with freshwater shell beads. However, shell beads are not the only material used as nuclei. In this study, freshwater non-bead cultured pearls were inserted as nuclei in saltwater hosts. Researchers from GIA’s Bangkok laboratory performed spectroscopy (UV-Vis, PL, and Raman), LA-ICP-MS chemical analysis, and microradiography and X-ray luminescence examination on 12 samples. Two samples were cut in half to further analyze their internal structures.

The results are available in a study titled "Atypical Bead Cultured Pinctada maxima Pearls Nucleated with Freshwater Non-Bead Cultured Pearls." The authors concluded that standard pearl testing methods permit the straightforward identification of such aBC pearls, and the ability to obtain more data from the pearls cut in half is a very useful method for further scientific examination. Source: GIA @topic:5


Title: X-ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls Abstract: The distinction of natural from cultured pearls traditionally has been based on X-radiography. X-ray computed microtomography (μ-CT) has recently been applied to gain more insight into pearl structures. Using this technique, this article presents features observed in a selection of natural pearls and beaded and non-beaded cultured pearls. Based on these observations, μ-CT is shown to be a powerful tool for pearl identification.

	DATA DEPOSITORY

	Supplementary Videos (see below)
	Summer, 2010

	Figures 1a and 1bTwo Natural Pearls

	Two natural pearls, samples mxt 3 (freshwater; a) and mxt9 (saltwater; b); for details and explanation, see table 1 and figure 3.

	Figure 2A Beaded Cultured Pearl

	A beaded cultured pearl, sample mxt 14b (saltwater); for details and explanation, see table 1 and figure 4.

	Figures 3a, 3b and 3cTwo Non-beaded Cultured Pearls

	Two non-beaded cultured pearls, samples mxt 1 (freshwater; a) and mxt 61_14 (saltwater; b). Also included is a short movie showing the rendered model of the cavity structure (“moustache”) in the center of sample mxt 1 (c); for details and explanation, see table 1 and figures 5 and 6.

	Figure 4A Non-beaded Cultured Pearl

	A non-beaded cultured pearl with a complex structure, sample mxt 21_1 (saltwater); for details and explanation, see table 1 and figure 8. Source: GIA @topic:5