Title: Large and Unusual Gems Abstract: Figure 1. Noor Gems showcased afghanite from Badakhshan Province, Afghanistan. Photo by Duncan Pay/GIA; courtesy of Noor Gems Japan Ltd.

              The inventory of Noor Gems Japan Ltd. at the GJX show was characterized by large and unusual gems, including a fine selection of rare blue and pink gemstones: afghanite, hauynite, hemimorphite, and pezzottaite. Bright blue afghanite (figure 1), which the company has been selling for three years, was available in gem quality in the 0.3–1.5 ct range, priced at approximately $500–$700 per carat. It has been especially popular with Noor’s Japanese clientele. Afghanite is a relatively soft stone for jewelry, with a hardness 5.5 to 6, best suited for pendants and earrings. While near-colorless material can be found in Italy and Germany, the recent production of blue afghanite is from Badakhshan Province, Afghanistan.

Mehraj Uddin exhibited two large topaz of exceptional pink to red color (6.38 and 12.08 ct). As with virtually all pink topaz, he acknowledged that these fine stones were heat treated. Debuting at Noor’s GJX booth was pinkish purple copper-bearing tourmaline from Mozambique (figure 2).

Figure 2. Another attraction at the Noor Gems booth was pinkish purple copper-bearing tourmaline from Mozambique, which they labeled as “Paraíba.” Photo by Duncan Pay/GIA; courtesy of Noor Gems.
For some large and exceptional gemstones, such as a 254.50 ct peridot cabochon from Pakistan, Uddin admitted they hold on to these stones for 10 or 20 years. The company is reluctant to sell them because of the difficulty in replacing such inventory. They will only sell when they feel the market is high. Source: GIA @topic:1


Title: Online Gem Exploration for Kids Abstract: GIA’s new GemKids site is not just for kids – parents and educators will want to use it too. The interactive, online gemology, geology and jewelry education site, geared toward 9-12-year-old students, is a great way for adults and children to explore the world of gems and jewelry together. The site is also user-friendly on desktops and mobile devices, so the learning experience can take place wherever it is most comfortable and convenient.

The “Gem Explorer” section highlights 24 popular gems – such as diamond, ruby and pearl – with fun facts about color, history and lore; name origin; image galleries and micrographs of the gem under different microscope magnification levels; and a localities map. The “Find My Gem” feature lets students explore different gems based on their birthday, favorite color or by country of origin. The “Story of a Gem” section describes the world of gems, including mineralogy, mining, cutting, phenomena, gem art and more. Additional gems will be added on an ongoing basis.

GemKids’ “Jewelry Explorer” describes seven categories of jewelry including rings, necklaces, crown jewels, memorial jewelry and timepieces. A “Jewelry Time Machine” traces the evolution of jewelry from prehistory to the modern era.

More than 160 gemological, geological and jewelry terms are defined in the “Glossary,” which also offers an audio pronunciation and descriptive image for each entry. Parents and educators can use the “Classroom Guides” to prepare interactive programs on gemology, geology and birthstones, or to prepare Boy Scouts and Girl Scouts for earning a merit badge. A “Careers” section describes 16 exciting jobs in the gem and jewelry field.

“Bringing engaging gem information that is fun for kids is a great way to extend our 83-year history as the world’s leader in gem and jewelry education,” said Bev Hori, GIA’s chief learning officer and vice president of education. “Students can learn about the fascinating world of gems directly on their computers and tablets, and teachers can use this information to supplement their science curriculums.”

The lessons are adapted from GIA’s Junior Gemologist Program™, which offers 10-15 year-old students the opportunity to discover the world of gemology through hands-on, practical training. Taught by expert gemologists and regularly offered at the Institute’s Carlsbad, Calif. campus and in other global locations, the program makes the complexities of gemology easily understood by all. It also meets federal curriculum guidelines, and enriches school district and youth science programs. GIA has partnered with Boy Scouts of America and Girl Scouts of the USA to create a specialized Jr. Gemologist Program where scouts can earn geology and jewelry merit badges, belt loops and pins.

Explore GemKids: Visit gemkids.gia.edu for more details. Source: GIA @topic:10


Title: Explore the Gem Encyclopedia Abstract: You may not have the time or means to go on a gem expedition, but GIA can guide you through one. This new website, which aggregates more than 80 years of gemology research, can help you explore the world of gems.

Whether you’re a consumer looking for information on a gem before you buy, a student considering a career in the gem and jewelry industry or someone who simply loves gems and minerals, you are sure to discover information here that reveals the beauty and wonder of gems.

This site features a comprehensive overview of gem information, starting with the GIA Gem Encyclopedia, a major new feature that highlights 21 of the most popular gemstones. Each has its own page with standout facts, information on treatments, synthetics and imitations, famous stones and a map of gem localities. It also includes eye-catching photography, video and a streamlined, content-rich format. The easy-to-navigate layout enables you to search by color or country of origin and toggle between rough and polished images of the stone.

Looking to buy a gem? Jump straight to a Buying Guide for tips on quality factors, gem care or how to find a jeweler. Whether you’re seeking advice on how to clean your diamond or the refractive index of tanzanite, you can find it in the Gem Encyclopedia.

“From someone in GIA’s Junior Gemologist program newly bitten by the gemology bug to researchers eager to tap into nearly 80 years of G&G  knowledge, the Gem Encyclopedia covers all levels of interest,” said Duncan Pay, editor-in-chief of G&G.

The gem pages also lead you to related articles on the Research & News section so you can easily browse from one topic to the next if you want more information.

“As you explore the pages you’ll find the more you learn, the more you can learn,” Pay said. “A consumer on the sapphire page will find useful, quick information, but they can also dig deeper and learn about fascinating research on new sapphire sources and see maps of where the gem is found.”

The new Research & News section is a quick reference to all G&G articles – dating back to 1934 – which are available to read on the website or download in a free PDF.  This section also features content from GIA global researchers and subject matter experts, including field reports, market analyses and the latest research updates.

	The Gem Encyclopedia overview provides broad information about each stone, but you
	can easily dig deeper with the embedded links. Source: GIA @topic:7


Title: Burmese Jade: The Inscrutable Gem Abstract: The jadeite mines of Upper Burma (now Myanmar) occupy a privileged place in the world of gems, as they are the principal source of top-grade material. This article, by the first foreign gemologists allowed into these important mines in over 30 years, discusses the history, location, and geology of the Myanmar jadeite deposits, and especially current mining activities in the Hpakan region. Also detailed are the cutting, grading, and trading of jadeite—in both Myanmar and China—as well as treatments. The intent is to remove some of the mystery surrounding the Orient’s most valued gem. Source: GIA @topic:12


Title: Gem Wealth of Tanzania Abstract: The East African nation of Tanzania has great gem wealth. First known by Westerners for its diamonds, Tanzania emerged in the 1960s as a producer of a great variety of other gems such as tanzanite, ruby, fancy-colored sapphire, garnet, and tourmaline; to date, more than 50 gem species and varieties have been produced. As the 1990s begin, De Beers has reinstated diamond exploration in Tanzania, new gem materials such as transparent green zoisite have appeared on the market, and there is increasing interest in Tanzania's lesser-known gems such as scapolite, spinel, and zircon. This overview describes the main gems and gem resources of Tanzania, and reviews their history, geology, mining, and economic development. Source: GIA @topic:1


Title: Synthetic Gem Materials in the 1980s Abstract: Although the 1980s did not experience the emergence of several totally new synthetics that characterized the preceding decade, it was during this period that synthetics matured, with many new manufacturers and greater manufacturing capacity. The highlights of this decade included the introduction of a number of new synthetic sapphires, rubies, and emeralds, as well as the appearance of the first commercially available cuttable synthetic diamond. The 1980s also saw the influx into the market of literally tons of synthetic amethyst and thousands of tons of synthetic cubic zirconia. As new synthetic products emerged, so did the need for new detection techniques. Developments during this decade will provide major challenges in the years to come. Source: GIA @topic:1


Title: Gem Localities of the 1980s Abstract: The 1980s saw major developments in new sources for diamonds and colored stones, as well as expanded production at many existing mines. This article identifies important new discoveries, as well as localities that were major gem producers, during the decade. Brief descriptions are provided for many of these, and their impact on the jewelry industry is reviewed. The article also provides an index to key recent publications on these occurrences. Source: GIA @topic:7


Title: Gem-Quality Green Zoisite Abstract: A new transparent, gem-quality green zoisite has been discovered in the Merelani Hills of mineral-rich Tanzania. The gemological properties are identical to those known for violetish blue tanzanite. The main differences are the pleochroic colors and the presence of chromium lines in the absorption spectrum of the green material. Chemical analyses demonstrated the presence of varying amounts of chromium and vanadium relative to the saturation of green. Source: GIA @topic:2


Title: Gem-Bearing Pegmatites: A Review Abstract: Many of the important gem minerals seen on today's market - aquamarine, tourmaline, and topaz, among others - come from an unusual type of rock known as a pegmatite. Gem-bearing pegmatites are crystalline igneous rocks that are distinguished by their large-size crystals, concentrations of certain chemical elements otherwise rare in the earth's crust, and various unusual minerals. Pegmatites are typically rather small bodies of rock that are found in particular geologic environments; the gem minerals occur in open cavities or "pockets" within the pegmatite. This article surveys our current understanding of pegmatites, beginning with a brief description of their characteristics and following with a discussion of the occurrence of gem minerals in them. The article concludes with a summary of the specific conditions necessary during pegmatite formation for the crystallization of abundant gem minerals. Source: GIA @topic:2


Title: 'Cobalt-Blue' Gem Spinels Abstract: The traditional gemological technique for distinguishing natural from synthetic blue spinel has involved the use of refractive index and absorption spectra. Recently, however, the standard interpretation of these tests has proved troublesome in the identification of several intensely colored blue stones that have R.I.'s in the range of natural blue spinels but that exhibit spectral features generally associated with synthetic cobalt-colored spinels. To establish the origin of these specimens, a detailed investigation of natural, flame-fusion, and flux blue spinels was carried out. Our results indicate that, while spectral features in the longer wavelengths are unreliable for separating these spinels, an iron-related absorption band at about 460 nm was seen only in our natural specimens. Flame-fusion synthetics may still be distinguished by their lower R.I.'s. Source: GIA @topic:3


Title: Gem Andradite Garnets Abstract: Andradite, the rarest of the five well-known gem garnet species, is examined and characterized with respect to refractive index, specific gravity, absorption spectrum, color, and chemical composition. These properties are measured and specifically tabulated for 21 gem andradrites (20 green and one yellow). From the narrow ranges of refractive index (1.880-1.883), specific gravity (3.80-3.88), and chemical composition (less than 3% of components other than andradite in any of the specimens examined) that were observed, it is apparent that the gem-quality andradrites are chemically distinct from other types of gem garnets and that these stones are easy to distinguish by means of color coupled with refractive index. Source: GIA @topic:2


Title: Engraved Gems: A Historical Perspective Abstract: Such innocuous events as the creation of the pre-gummed envelope and the modem postal system contributed to the demise of the engraved gem seal. During the thousands of years that the seal served as man's most important mark of identification, however, gem engraving reigned as one of his most significant art forms. This article traces the-history of engraved gems from primitive amulets through cylinder seals, scarabs, scaraboids, and ringstones, to the more recently introduced cameos. Also discussed is the engraving process itself, how to evaluate an engraved gem, and more recent developments in the materials and methods used to engrave gems. Source: GIA @topic:10


Title: A Computer Program for Gem Identification Abstract: Following a feasibility study of computer-aided gem testing, which resulted in a student-level gem identification program, the author has developed a professional version containing data on over 200 gem materials and gem simulants. The program sections include Gem Identification (using test inputs for R.1, values, optic sign, S.G., etc.), Gem Data Tables (arranged in alphabetical, R.I., and S.G. order), Gem Data Comparisons, Gem Data Pages, and Gem Calculations (for determinations of S.G., reflectivity, critical angle, and Brewster angle). This type of computer program provides rapid access to gem constants and characteristics, and can assist the less experienced gemologist by identifying unfamiliar or rare stones and indicating the various alternatives. Source: GIA @topic:7


Title: Gem-Quality Grossular Garnets Abstract: The gemological classification and identification of gem grossular garnets is examined through the study of 105 gem-quality grossulars. These specimens were measured for refractive index, specific gravity, absorption spectrum, color, and chemical composition. From these data, the authors were able to reexamine the ranges of physical and optical properties that are characteristic of the gem species grossular. In addition, they discuss the problems encountered in defining the two gem varieties of grossular, tsavorite and hessonite. Source: GIA @topic:2


Title: Sri Lanka: The Gem Island Abstract: Sri Lanka, formerly Ceylon, remains one of the single most important sources for fine gemstones. Especially notable are blue sapphire, pink sapphire or ruby, and yellow sapphire; alexandrite and cat's-eye chrysoberyl; and almandine and hessonite garnet. Spinel, tourmaline, zircon, moonstone, and quartz are also relatively common; they share their country of origin with several rarer gemstones as well. Most of the gem-quality material is found in alluvial deposits throughout the island, which are mined by primitive methods. In many instances, the Sri Lankan origin of the gemstone can be determined by characteristic inclusions, several of which are also discussed in this article. Source: GIA @topic:1


Title: Color In Gems: The New Technologies Abstract: Advances in technology have brought great advances in our ability to impart color to natural gemstones as well as to create synthetics. Simultaneously, technologies are also being developed to distinguish natural from artificial colors as well as natural from synthetic materials. This article discusses some of the work being done to enhance color in gemstones today and some of the techniques used by the laboratories at the California Institute of Technology to determine whether a color originates naturally or in the laboratory. Dyed jade, synthetic turquoise, heat-treated beryl and zircon, irradiated spodumene, and topaz that has been irradiated and heat treated to produce a pleasing blue color are some of the specific examples included. Source: GIA @topic:1


Title: Gem Crystals – Tucson 2014 Abstract: Figure 1. Tiny calcite crystals adhering to the surfaces of this superb tanzanite crystal, along with the brown coloration around its base, are strong indicators that the material has not been heated. The crystal weighs 500.45 ct and measures approximately 8 cm in length. Photo by Eric Welch; courtesy of New Era Gems.

              At the Pueblo Show, Steve Ulatowski (New Era Gems, Grass Valley, California) told us how the dynamics of his business have shifted from facet-quality rough to crystal specimens, which now make up more than 80% of his turnover by dollar value. In particular, small gem crystals in wire-wrapped jewelry now form a large part of his commerce.

	Steve UlatowskiNew Era Gems

	Gem-trade veteran Steve Ulatowski describes the recent market changes have driven prices for rough colored gems of all types to unprecedented heights. He explains the impact on his business and reveals some of the key factors behind these momentous market dynamics.
Ten years ago, facet rough made up 90% of New Era’s business, while gem crystals were a mere 5%. Facet rough now represents just 10% of his total, because it is nearly unobtainable.

As an example of changing market dynamics, Ulatowski showed us a fine tanzanite crystal (figure 1), which previously would have been more valuable as a mineral specimen. In today’s frenzied market, such a crystal might be worth $45,000 uncut but command $50,000 as rough for faceting.

According to Ulatowski, the criteria for a superior gem crystal include luster, color, and the condition of its edges (absence of nicks or chips). Whether or not it has a perfect termination also plays a role. Another consideration is the potential amount of cuttable material. For example, a 109- gram tanzanite crystal might yield 80 grams (400 carats) of cutting material, which would yield on average about 160 carats of fashioned gems.

Ulatowski noted that due to demand for cutting rough in late 2013, many crystals were broken for that purpose. Fine, well-formed crystals once commanded a premium over those suitable only for cutting fashioned gems; a fine crystal might be worth twice as much if left as a specimen. Although fine crystals are exceptionally rare, the market for cutting rough is tremendous right now, with worldwide shortage of every type of cutting material—even staples like blue topaz and smoky quartz. He has never seen a rough shortage comparable to this current one. Like other dealers at the shows, Ulatowski believes this represents a combination of less global mining activity, stricter mining regulations in many countries, rising fuel costs, and growing Asian demand.

Still, his U.S. client base is reluctant to pay higher prices for what they perceive as overpriced rough. There is also a growing trend toward better cutting at the source, with governments trying to support their own domestic cutting industries, as this retains more value in country than merely exporting the rough as raw material.

	Figure 2. This 335.46 ct crystal contains relatively little cuttable material, but its crystal form and condition are excellent, making it worth five times more as an uncut specimen. The cuttable portion is located near the tip of the crystal, where the rough begins to narrow, so there is not enough depth for a significant faceted stone. Photo by Eric Welch; courtesy of New Era Gems.
Ulatowski had a range of unheated tanzanite crystals, which he estimated might make up 20% of total rough tanzanite production. He showed us many examples with blue to green terminations and brown coloration near the base (figure 2). A few blue crystals included calcite matrix, while some had associated pyrite.

Although many in the trade say all blue tanzanites have been heated, Ulatowski explained that it is impossible to heat only part of a crystal. Therefore, any crystal that is brown on the base has not been heated. In many specimens, the brown base is best for cutting, as it is usually the widest part of the crystal.

Demand for what Ulatowski calls “fancy tanzanite” (zoisite) is strong, with top pink colors selling for up to $800 per carat. Unheated natural pinks usually form only in the tip of the crystal, so most stones are small (less than a carat). The most valuable specimens are pure pink, with no purple cast.

	Figure 3. This 765.00 ct tanzanite crystal was heated in an oven at approximately 1000°F to remove all brown coloration. After the temperature was raised incrementally over a number of hours, the peak temperature was maintained for one hour before gradual cooling over a period of six to eight hours. Prior to heating, the crystal was completely brown, with no traces of blue. Photo by Eric Welch.
For contrast, Ulatowski showed us a heated crystal where the brown coloration had been removed (figure 3), as well as a natural unheated reddish brown sample (figure 4) with no hint of blue. He also had a range of green grossular garnet crystals, a byproduct of Merelani tanzanite mining (figure 5). Also remarkable were bicolor tourmaline crystals (figure 6) with an unusual etched core but intact terminations. These were reportedly from the Barra de Salinas mine in Minas Gerais, Brazil.

	Figure 4. Specimen crystals, such as this 87.59 ct natural-color unheated reddish brown zoisite, are currently the mainstay of Steve Ulatowski’s business. Photo by Eric Welch; courtesy of New Era Gems.
In closing, Ulatowski noted that his best sales year at Tucson was 2013, but that 2014 was headed in the same direction.

	Figure 5. In Merelani, green grossular garnet (tsavorite or “mint” garnet) is a byproduct of tanzanite mining. This unusual 27 ct group of intact euhedral crystals measures approximately 4 cm in length. It is a “floater,” meaning there is no visible attachment to any host rock. Photo by Eric Welch; courtesy of New Era Gems.

	Figure 6. These bicolor tourmaline crystals are reportedly from the Barra de Salinas mine near Coronel Murta in Minas Gerais, Brazil (left). Each 2–3 cm crystal had a heavily etched, almost skeletal pink core topped by a euhedral or very slightly etched green cap. The terminations (right) may have projected into a layer of clay minerals during formation, protecting them from etching. Photos by Eric Welch; courtesy of New Era Gems. Source: GIA @topic:1


Title: An Introduction to Spectroscopy in Gem Testing Abstract: When Isaac Newton first held a prism up to the sun, he scarcely could have imagined the influence of the spectroscope on modern gem testing. In the early 1950s, GIA’s Robert Crowningshield became expert at using this instrument to identify gems, including enhanced and imitation goods. This article shares Crowningshield’s methods, including several original drawings of spectral bands that reveal how certain gemstones selectively transmit or absorb light, yielding valuable clues to their identity. Source: GIA @topic:1


Title: How to Choose a Gem of a Jeweler Abstract: Purchasing a piece of jewelry requires important decisions. Just as you consult with other professionals for important advice, such as a family doctor or lawyer, you should turn to a professional jeweler to make a jewelry purchase a pleasurable event.

Here are some guidelines for selecting a professional jewelry.

First, a professional jeweler should have the knowledge and training to help you make an informed purchase. Look for credentials that indicate professional experience. For example, the initials GG (Graduate Gemologist) after a jeweler’s name indicate that the jeweler has had a high level of gemological training. A GG should be up to date on the industry’s most relevant developments through GIA’s continuing education programs such as the Continuing Education Recognition Program.

In addition to product knowledge, a jeweler’s reputation is one of his or her most valuable assets. Ask friends for recommendations, or ask a jeweler to provide references. Find out how long the jeweler has been in business, check for affiliations with industry associations and ask whether he or she is an active member of the GIA Alumni Association.

If you are buying a diamond or colored gemstone, consider getting a report from an independent laboratory with your purchase. For example, professional jewelers worldwide provide independent diamond grading reports with their fine diamonds. The most widely used and respected are those issued by the GIA Laboratory, which created the diamond grading system. A jeweler can even arrange to have a diamond’s unique GIA Diamond Grading Report number, or even a personal message, laser inscribed onto its girdle (outside edge) for easy identification.

Be sure to ask jewelers about the types of services they provide – such as repairs, appraisals, and inscriptions – the range of products offered and the store’s return policy and credit terms. Source: GIA @topic:7


Title: “Lily Pad” Structure in an Orangy Yellow Pearl Abstract: Figure 1. The orangy yellow pearl weighing 4.14 ct and measuring 9.51 × 8.43 × 7.51 mm. Photo by Gaurav Bera.
GIA’s Mumbai laboratory recently received for identification an orangy yellow semi-baroque pearl weighing 4.14 ct and measuring 9.51 × 8.43 × 7.51 mm (figure 1). Externally, the pearl had a distinct indentation on its top portion and possessed a medium surface luster. Observation of the surface under 40× magnification showed typical fine overlapping platelets of aragonite.
Energy-dispersive X-ray fluorescence revealed a manganese level below detection limits and a strontium level of 1226 ppm. When exposed to X-ray fluorescence, the pearl showed an inert reaction. Both results confirmed the pearl’s saltwater origin. Under long-wave ultraviolet light, it exhibited a yellowish green reaction. Raman analysis using a 514 nm laser excitation revealed a doublet at 701 and 704 cm–1 and a peak at 1085 cm–1, indicating the presence of aragonite. Photoluminescence spectra revealed two strong broad peaks at 620 and 650 nm as well as one weak peak at 680 nm, confirming the pearl’s natural color origin.

Figure 2. A: RTX image revealing a unique acicular “lily pad” feature with tiny flame-like structures. B: μ-CT scan displaying a small central core with elongated spiky features. C: A magnified μ-CT scan showing the spiky features surrounded by prominent growth arcs.
Upon further testing using real-time X-ray microradiography (RTX), the pearl displayed an unusual acicular feature resembling the shape of a lily pad, with tiny flame-like structures radiating from the center. This feature was intersected by several growth arcs (figure 2A). X-ray computed microtomography (μ-CT) provided a more detailed view, revealing a distinct small void at the center. Surprisingly, the acicular “lily pad” feature observed in the RTX images appeared as numerous elongated, spiky structures with very fine lines cutting through the shape (figure 2, B and C).

Figure 3. The 3D models generated using μ-CT scans show the acicular feature in red resembling a lily pad with a small core at the center, while the green area represents the pearl’s growth structure.
To further study this feature, three-dimensional models were created using specialized software to render the μ-CT scan images (C. Zhou et al., “New 3-D software expands GIA’s pearl identification capabilities,” GIA Research News, May 13, 2016). In both the μ-CT scan images and the 3D models shown in figure 3, it was evident that this unique feature was confined to the central part of the pearl and did not extend to the outer nacre layers. Notably, the lily pad feature had elongated spikes that were thicker at one end and gradually tapered as they radiated outward from the center.
Gemological laboratories do encounter pearls with internal structures that are very difficult to positively identify. Due to the lack of conclusive evidence proving it was a cultured pearl combined with the presence of a rare and distinctive natural structure, this pearl was considered noteworthy. Such intriguing natural growth structures can be influenced by several factors, including environmental conditions, the health of the mollusk during formation, and other external causes impacting the pearl formation process. The precise mechanism of natural pearl formation continues to be widely debated, and encountering such pearl samples causes us to further contemplate the creation of these exquisite gems. Source: GIA @topic:5


Title: Large Freshwater Cultured Pearls with Atypical Bead Nuclei Abstract: Figure 1. These two necklaces consisting of large freshwater cultured pearls displayed strong hues with orient. Photos by Sood Oil (Judy) Chia; courtesy of Yvel.
Freshwater cultured pearls are known for their wide range of attractive colors, including different combinations of white, orange, pink, and purple hues. In the past decade, round or near-round freshwater bead cultured pearls of large size, commonly called “Edison” pearls in the trade, have gained popularity (Summer 2015 Lab Notes, pp. 179–181; C. Zhou et al., “Detection of color treatment and optical brightening in Chinese freshwater ‘Edison’ pearls,” Summer 2021 G&G, pp. 124–134). Recently, two necklaces consisting of large pearls of mostly orangy pink to purplish pink colors (figure 1), ranging in size from 15.40 to 17.42 × 16.70 mm and from 18.00 to 19.96 × 19.06 mm, were submitted to GIA’s New York laboratory. The strands caught our attention for their size and intense colors, as well as the growth features found inside these pearls.

Figure 2. RTX analysis revealed the near-round atypical bead nucleus used to culture each of the pearls.
Real-time X-ray microradiography (RTX) revealed that all the pearls were bead cultured—but not with the shell bead nuclei typically used for cultured pearls. Instead, a more X-ray transparent material with a distinct outline and near-round shape was found inside them (figure 2). The material appeared porous and nonuniform and did not resemble the “mud-like” material found in “soufflé” freshwater cultured pearls previously studied (Spring 2010 Gem News International, pp. 61–63). However, the exact nature of this material could not be determined. Energy-dispersive X-ray fluorescence analysis of their trace elemental concentrations (such as manganese and strontium) confirmed that the pearls were grown in a freshwater environment. Furthermore, Raman spectroscopy using 514 nm laser excitation indicated that their colors were natural, with two strong peaks around 1125 and 1510 cm–1 associated with natural polyenic pigment.
Cultured freshwater pearls with large size, near-round shape, and intense coloration are highly sought after and more valuable than traditional freshwater cultured pearls. These large freshwater cultured pearls are especially noteworthy because of the unique bead nuclei used during the culturing process, which suggests that culturing techniques are continuously evolving, resulting in higher-quality products. Source: GIA @topic:5


Title: Seed Pearls in an Antique Indian-Style Headdress Abstract: Figure 1. This antique Indian-style headdress is decorated with handwoven light cream and cream-colored seed pearls. Photo by Gaurav Bera.
Identification of seed pearls often poses a challenge to gemologists. Seed pearls are typically smaller than 3 mm and can be of either saltwater or freshwater origin (The Pearl Blue Book, CIBJO, 2022). These tiny pearls have long been used for adornment on clothing, jewelry, and various decorative items.
Recently, GIA’s Mumbai laboratory examined an antique headdress (figure 1) submitted for pearl identification service. The exquisite headdress, which according to the client dates back several decades, featured intricate embroidery on a red velvet base. It incorporated approximately 7,000 light cream and cream-colored pearls, most of which displayed a strong orient. These pearls, ranging from semi-baroque to baroque in shape, were meticulously hand-woven onto the headdress using white silk thread and further secured by a surrounding framework of twisted white metal wire. The headdress itself weighed 240 g, and most of the pearls measured around 2.10 mm, with some larger ones reaching up to 3.40 mm.

Figure 2. Left: Long-wave ultraviolet reaction displaying a greenish yellow reaction and an occasional yellowish brown reaction. Right: Freshwater pearls emitting a strong yellowish green XRF reaction; some orangy red fluorescence suggesting vaterite.
Under a 10× loupe, some of the pearls displayed slight wear around the drill hole, while maintaining an overall intact nacre condition with a medium to high surface luster. The pearls embroidered on top of the headdress displayed nacreous overlapping aragonite platelets (platy structure) patterns, which are typically observed in pearls from a saltwater environment. Those on the side portion exhibited slightly broader platy patterns, which are common in freshwater pearls. Under long-wave ultraviolet radiation (figure 2, left), most of the pearl samples showed weak greenish yellow fluorescence, with a small percentage showing yellowish brown. A similar weaker reaction was observed under short-wave ultraviolet radiation (not shown).
When exposed to X-ray fluorescence, the pearls on top of the headdress were inert, indicating their saltwater origin. In contrast, the pearls on the side portion showed a strong yellowish green fluorescence due to high manganese contents, indicating a freshwater origin (figure 2, right). Interestingly, some freshwater pearls also displayed an orangy red fluorescence, suggesting the presence of vaterite, a less commonly observed form of calcium carbonate (CaCO3) compared to aragonite or calcite (Winter 2021 Lab Notes, pp. 377–378). Due to the size and delicate nature of the headdress, further analysis of chemical composition using energy-dispersive X-ray fluorescence spectrometry was not feasible.

Figure 3. Left: RTX image of pearls from the top portion of the headdress (saltwater environment). Right: RTX image of pearls from the side portion (freshwater environment).
To study the internal structures, the authors performed random sampling using real-time microradiography (RTX) imaging (figure 3). Internally, most of the saltwater pearls exhibited small organic-rich cores with fine growth arcs, while other samples displayed tight to minimal structures with a few fine growth arcs toward the outer nacre. These internal structures were similar to those observed in natural pearls from the Pinctada species. Similarly, the freshwater pearls displayed natural structures with growth arcs throughout the pearl, consistent with natural freshwater pearls from GIA’s research database (Summer 2021 Gem News International, pp. 167–171). Twisted linear structures or voids, which are commonly found in non-bead cultured Chinese freshwater pearls, were also observed in a minority of the tested samples (K. Scarratt et al., “Characteristics of nuclei in Chinese freshwater cultured pearls,” Spring 2000 G&G, pp. 98–109).
Although the identification of seed pearls has always presented challenges and limitations, advancements in equipment and instrumentation available at GIA laboratories enable the detailed analysis of even the most minute structures and features in pearls, whether natural or cultured. Source: GIA @topic:5


Title: Natural Freshwater Pearls from Europe: Russia, Scotland, and Germany Abstract: Figure 1. The eight European natural freshwater pearls reportedly produced by Margaritifera mussel species, collected from freshwater sources in Russia, Scotland, and Germany. Photo by Diego Sanchez.

The Carlsbad laboratory received eight European freshwater (FW) pearls from coauthor ES for gemological and chemical characterization (figure 1). Although the exact locations and times of discovery were not recorded, all the samples were obtained directly by ES from reputable sources in each country. The first three samples are of Russian origin and were obtained by Russian fisheries biologist Valery Ziuganov during his studies of the Varzuga River, Kola Peninsula, in the 1990s (E. Strack, “European freshwater pearls: Part 1–Russia,” Journal of Gemmology, Vol. 34, No. 7, 2015, pp. 580–593; E. Strack, “Freshwater pearls from Russia,” Margaritologia newsletter, No. 11, 2018). Two samples from Scottish rivers were provided in 2004 by Cairncross Jewellers, the only company allowed to buy pearls from the fishers in Perth, Scotland. The last three are from Lüneburg Heath in northern Germany and were supplied around 1997 by a local family that had collected and fished for pearls over the decades. European FW natural pearls have reportedly been produced for centuries from mussels belonging to the Margaritifera species, which has been referred to as the “freshwater pearl mussel” (E. Strack, Pearls, Rühle-Diebener-Verlag, Stuttgart, Germany, 2006). Today, most natural FW pearls produced in North America and cultured FW pearls from Asia form in various mussel species within the Unionidae family. Both families are member of the Unionoidea superfamily.

The samples exhibited two different surface structures: nacreous and non-nacreous. Upon examination with a loupe and microscope, samples 1–4 (see table 1) exhibited nacreous surfaces, with fine overlapping platelets visible under high magnification. Surface wrinkling was also seen in single areas on samples 1 and 3, along with fine surface fractures; the wrinkled feature in each was previously noted as a characteristic of a FW environment (Strack, 2015, 2018). The nacreous samples ranged from 0.70 to 2.68 ct and measured from 4.77 × 4.33 mm to 7.08 × 6.72 mm. According to GIA classification procedures, their shapes were semi-baroque, baroque, and circled oval, while their bodycolors varied from light pinkish brown to light purplish pink and very light pinkish brown. Sample 3 showed a dull surface lacking luster and overtone, while the other three displayed orient and pink overtones.

Figure 2. At higher magnification, the four non-nacreous pearls displayed mosaic or cellular surface patterns of different sizes and shapes. This image shows the cellular structure on the surface of sample 7 when illuminated with a fiber-optic light. Photomicrograph by Nathan Renfro; field of view 1.00 mm.
Conversely, samples 5–8 exhibited a non-nacreous surface appearance and lacked overlapping platelets characteristic of most FW pearls. They ranged from 0.94 to 2.11 ct and measured from 5.12 mm to 7.32 × 6.98 mm. The shapes were uniformly round, oval, and drop, and all the samples were brown-yellow. At higher magnification, using strong illumination such as fiber-optic lighting, all the pearls displayed mosaic or cellular surface patterns of differing sizes and shapes. The small cells, which looked like pinpoint features in lower lighting conditions, resulted in a dimpled surface texture (figure 2). A cellular pattern was also observed in a small area on the base of sample 1. The non-nacreous appearance and cellular surface structures resembled those commonly observed on pen pearls from the Pinnidae family (N. Sturman et al., “Observations on pearls reportedly from the Pinnidae family (pen pearls),” Fall 2014 G&G, pp. 202–215), as well as some non-nacreous non-bead cultured pearls from the Pinctada maxima mollusk (A. Manustrong et al., “Known non-nacreous non-bead cultured pearls and similar unknown pearls of likely cultured origin from Pinctada maxima,” GIA Research News, 2019, https://www.gia.edu/gia-news-research/known-non-nacreous-non-bead-cultured-pearls). Non-nacreous natural pearls from Pteria species mollusks have also reportedly displayed hexagonal-like cellular patterns (S. Karampelas and H. Abdulla, “Black non-nacreous natural pearls from Pteria sp.,” Journal of Gemmology, Vol. 35, No. 7, 2017, pp. 590–592).

Figure 3. Raman spectra of all eight samples obtained using an 830 nm diode laser revealed clear aragonite peaks, a doublet at 702 and 705 cm–1 (magnified in the inset), and a single intense band at 1085 cm–1. These results allowed the four non-nacreous pearls to be separated from pen pearls, which are normally composed of calcite (Sturman et al., 2014). Spectra are offset vertically for clarity.
Under long-wave ultraviolet radiation (365 nm), the nacreous samples exhibited weak bluish yellow fluorescence over most of the surface, while a yellow reaction was observed on the limited yellowish brown areas. The non-nacreous samples exhibited uniform weak to moderate chalky yellow fluorescence similar to that reported for pen pearls (Sturman et al., 2014), but different from the strong orangy red fluorescence observed in non-nacreous Pteria pearls (S. Karampelas and H. Abdulla, 2017).
A Raman spectrometer was used to examine the surface composition of all the pearls, initially using a 514 nm argon-ion laser. Owing to the high background fluorescence observed in most of the samples, an 830 nm laser provided better peak resolution. Clear aragonite peaks at 702, 705, and 1085 cm–1 were recorded in all the samples (figure 3), and the results allowed the four non-nacreous pearls to be separated from pen pearls, which are normally composed of calcite (Sturman et al., 2014). Raman spectra collected using the 514 nm laser revealed weak polyene peaks at approximately 1125 cm–1 and 1512 cm–1 in samples 1, 3, and 4, indicating their colors were natural. Polyene peaks were not observed in samples 2 and 5–8, possibly due to the samples’ high fluorescence. The 830 nm laser is not helpful in resolving polyenic peaks. Surface observations did not reveal color modification in any of the samples.
UV-Vis reflectance spectra were collected from the smoothest and most homogeneously colored area of each sample in the 250–800 nm range. An absorption feature at about 280 nm that is usually observed in nacreous pearls was clearly seen in samples 1–4 but absent in samples 5–8. Samples 1, 2, and 4 showed reflection minima in the blue to yellow range, which corresponds with their predominantly pink hue. These results correlate with those in a previous study on naturally pink FW pearls of natural origin from the Mississippi River System in the United States (Summer 2019 GNI, pp. 282–285) and with reports on natural-color FW cultured pearls from Hyriopsis species mollusks (S. Karampelas et al., “Role of polyenes in the coloration of cultured freshwater pearls,” European Journal of Mineralogy, Vol. 21, No. 1, 2009, pp. 85–97; A. Abduriyim, “Cultured pearls from Lake Kasumigaura: Production and gemological characteristics,” Summer 2018 G&G, pp. 166–183). Owing to the very light color of sample 3, the spectrum obtained was nearly flat, as would be expected for white pearls, and hence no features of any significance were observed. The spectra obtained from samples 5–8 showed a lower reflectance than the four previously reported samples due to their more saturated colors. All the spectra showed similar patterns, with an incline from 400 to 750 nm in the visible region, comparable to the reported spectra of dark-colored pen pearls (Sturman et al., 2014) and non-nacreous non-bead cultured pearls from Pinctada maxima (Manustrong et al., 2019).
Table 1 shows the internal structures of the eight samples using real-time microradiography (RTX) and X-ray computed microtomography (µ-CT). Sample 1 and all the non-nacreous samples showed clear organic-rich concentric ring structures with faint radial features radiating outward from the center across the concentric rings. The radial structures are associated with cellular surface patterns. All three sections of sample 2 showed weak growth arcs corresponding to their shapes. Sample 3 exhibited a wavy concentric growth pattern together with a dark organic-rich patch, while µ-CT analysis revealed a small dark core in the structure. Sample 4 displayed the least amount of visible structure—only a few very faint growth arcs, even when examined using µ-CT. Cracks of varying lengths and degrees of visibility were present in the samples. The structures observed confirmed their stated natural origin. However, a smaller nucleus with a lighter gray core next to the main nucleus in sample 7 did raise some concerns. If the pearl was submitted to a gemological laboratory without any known provenance, the smaller structure could be mistaken for the lighter gray carbonate “seed” features sometimes found in saltwater non-bead cultured pearls (M.S. Krzemnicki et. al., “Tokki pearls: Additional cultured pearls formed during pearl cultivation: External and internal structures,” 32nd International Gemmological Conference, 2011, https://www.ssef.ch/wp-content/uploads/2018/01/SSEF_Tokki_pearls.pdf). However, the authors are not aware that this type of feature has ever been reported in non-bead cultured pearls from a FW environment.
Chemical compositions were initially analyzed by energy-dispersive X-ray fluorescence (EDXRF) spectrometry, and some of the samples were tested twice in different positions. Most samples contained relatively low manganese (Mn) levels (0 to 240 ppm) compared to the majority of natural and cultured FW pearls in GIA’s database. The usual Mn range observed is between 150 and 2000 ppm. Samples 1, 3, and 6–8 showed Mn concentrations below 50 ppm. It was interesting to note that in sample 5, Mn was absent at one end but present (170 ppm) at the opposite end. Additionally, the samples with low Mn levels (<50 ppm) did not show visible reaction under X-ray excitation (H. Hänni et al., “X-ray luminescence, a valuable test in pearl identification,” Journal of Gemmology, Vol. 29, No. 5/6, 2005, pp. 325–329), as would be expected for such low traces of the element. Strontium (Sr) contents were relatively low (<1000 ppm) in all the samples, which is characteristic of FW origins. However, the very low concentration of Mn and lack of X-ray fluorescence reactions could create some doubts and lead to some misidentifying them as saltwater (SW) pearls.

Detailed trace element concentrations were analyzed using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) with the same parameters used in previous FW pearl studies (A. Homkrajae et al., “Provenance discrimination of freshwater pearls by LA-ICP-MS and linear discriminant analysis (LDA),” Spring 2019 G&G, pp. 47–60; Summer 2019 GNI, pp. 282–285). At least three ablation spots were tested on each sample, and the results for the 22 elements selected are shown in table 2. The five elements (sodium, magnesium, Mn, Sr, and barium) found to be useful discriminators in the differentiation of FW from SW pearls and in classifying FW pearls from different sources are bolded in the table. Mn and Sr contents obtained were consistent with the EDXRF results.

Figure 4. All the European pearl samples contained Mn levels below 500 ppm, which helped separate them from the majority of freshwater pearls previously studied. Mn and Sr levels obtained by LA-ICP-MS analysis were consistent with the EDXRF results. Yellow spots represent results from American natural pearls (USA-NAT), red spots from American cultured pearls (USA-CUL), green spots from Chinese NBC pearls (CH-NBC), and purple spots from American natural pearls from the Mississippi River System (USA-LP).
All the samples contained low Mn levels (<500 ppm), separating them from the majority of FW pearls previously studied (figure 4; see Homkrajae et al., 2019; Summer 2019 GNI, pp. 282–285). The ternary diagram of relative percentages between Ba, Mg, and Mn that was used to verify the growth environment conditions of the questionable FW pearls in previous studies (Homkrajae et al., 2019; Summer 2019 GNI, pp. 282–285) was used once again to confirm the formation environment of the six samples containing low levels of Mn (below 100 ppm). All six samples plotted alongside those of the FW pearls previously studied, confirming their FW origin. These results also help to distinguish non-nacreous samples from saltwater non-nacreous non-bead cultured pearls produced by Pinctada maxima (Manustrong et al., 2019). The values of these five discriminant elements, as well as those for lead (Pb), correspond with the chemical results reported on natural FW pearls produced by Margaritifera mollusks found in the Spey River, Scotland (S. Karampelas et al., “Chemical characteristics of freshwater and saltwater natural and cultured pearls from different bivalves,” Minerals, Vol. 9, No. 6, 2019, p. 357). The Sr-Ba concentration plot is also shown in figure 5. This result supports the observation made by Karampelas et al. (2019). Furthermore, the pearls from each European locality could be separated from each other in this plot, though it should be noted that this was based on a very limited number of known samples.

Figure 5. American and Chinese freshwater pearl samples studied previously, together with the samples from this study, were plotted in the Sr-Ba concentration plot. This result supports the observation made by Karampelas et al. (2019). Although the study was based on a limited sample pool, the pearls from each European locality could also be separated using this plot.
For centuries, the freshwater mussel species Margaritifera was abundant in the rivers and streams of Europe, and the pearls produced were part of European culture and history. The American native mussel species followed a similar path. However, environmental changes, and the impact of pollution from industry and agriculture have damaged ecosystems and directly affected the mussels’ habitat and lifespan (Strack, 2006). Freshwater pearl fishing in Europe is currently prohibited or under regulation due to the decline of mussel populations. Studying these rare European FW natural pearls provided valuable data that has enlarged GIA’s identification database, offering a useful reference for the gemological community. Source: GIA @topic:5


Title: Vaterite Found on a Strand of Freshwater Cultured Pearls Abstract: Figure 1. Single-strand freshwater bead cultured necklace measuring 10.33 × 10.18 mm to 13.36 × 12.72 mm. Photo by Sood Oil (Judy) Chia.

Recently, GIA’s New York laboratory received a single-strand necklace with 32 pearls for identification (figure 1). The pearls were white and near-round, ranging from 10.33 × 10.18 mm to 13.36 × 12.72 mm in size and weighing 81.50 grams total. Real-time microradiography (RTX) analysis revealed that all of them had a bead nucleus. Chemical analysis by EDXRF spectrometry showed a high manganese concentration and low strontium, indicating they formed in a freshwater environment. During examination of the strand, random white patches were observed on the surface of many of the pearls. These irregular patches appeared overgrown on the surface and crystalline-like (figure 2).

Figure 2. Irregular whitish patches were visible on the surface of many of the pearls. Photos by Sally Chan Shih.
X-ray fluorescence analysis revealed a strong yellowish green reaction around each pearl, while the irregular white surface patches showed a reddish orange reaction with moderate intensity (figure 3).

Figure 3. X-ray fluorescence analysis of the strand showed a yellowish green reaction along with a reddish orange reaction on the irregular white patches. Photos by Sally Chan Shih.
Additionally, Raman analysis of the nacreous surface and the irregular white patches revealed they consisted of two calcium carbonate polymorphs: aragonite and vaterite, respectively (figure 4). Aragonite peaks were observed at 701, 704, and 1085 cm–1; vaterite peaks were at 740, 750, 1075, and 1090 cm–1.

Figure 4. Raman analysis found aragonite peaks at 701, 704, and 1085 cm–1 and vaterite peaks at 740, 750, 1075, and 1090 cm–1.
Formation of the shells and pearls relies on the epithelial cells of the mollusk. Aragonite and calcite are the two most common calcium carbonate polymorphs found in pearls, while vaterite is the third most common and also the least stable form. Vaterite has only been found in freshwater pearls so far (Li Qiao et al., “Special vaterite found in freshwater lackluster pearls,” Crystal Growth & Design, Vol. 7, No. 2, 2007, pp. 275–279; Summer 2021 Gem News International, pp. 171–174). Although the reason why vaterite formed on the pearls’ surface is unknown, the defect is one of the most unusual formations seen, especially in an entire strand. Source: GIA @topic:5


Title: Freshwater Bead-Cultured Pearls with Multiple Features of Interest Abstract: Figure 1. Eleven of the 24 pearls in this necklace exhibited a shape like a dumbbell or peanut shell, which corresponded with the internal twin bead structure revealed by subsequent microradiography. Photo by Johnny Leung.

GIA’s Hong Kong laboratory recently examined a necklace consisting of 24 white baroque-shaped nacreous pearls ranging in size from 21.92 × 15.24 mm to 24.95 × 15.12 mm (figure 1). Their external appearance, high luster, and strong orient hinted at a freshwater origin. Detailed examination revealed additional features of interest.

Figure 2. A small whitish non-nacreous region was observed on one pearl under white light (left). The optical X-ray fluorescence image (right) revealed a strong green fluorescence reaction, as expected for freshwater pearls. An atypical reddish orange reaction was observed on the whitish non-nacreous portion. Photos by Sharon Tsz Huen Wu.
While their appearance was indicative of freshwater pearls, energy-dispersive X-ray fluorescence analysis was performed on a random selection to confirm their formation environment. The high manganese concentrations of 751–1728 ppm were consistent with freshwater pearls. In keeping with the reactions seen in freshwater pearls with such levels of Mn, the samples exhibited strong green fluorescence when exposed to X-rays. However, one in particular displayed moderate to strong reddish orange fluorescence on some areas of its surface (figure 2), associated with whitish non-nacreous regions on the pearl. Similar reddish fluorescence reactions had previously been observed around damaged areas of nacre on pearls examined in GIA’s New York laboratory (Summer 2013 Lab Notes, pp. 113–114). The exact reason for this reaction, which GIA gemologists have seen in cultured and natural freshwater pearls from time to time, is unknown.

Figure 3. Microradiographs revealed two round bead nuclei in one of the dumbbell-like pearls (left) and a network of tubules in the beads, resembling the parasite tubes commonly associated with saltwater shells (right). X-ray contrast permits the observation of structures near the surface and nearer the center of the pearls. Images by Sharon Tsz Huen Wu.
Eleven of these pearls had a shape resembling a dumbbell or peanut shell, indicating the possible presence of two nuclei in each. Real-time microradiography confirmed the presence of two round bead nuclei in these pearls (figure 3). The remaining 13 contained only a single round bead, consistent with the majority of bead-cultured pearls on the market. In addition, a network of tubules was observed within most of the bead nuclei. Such tubules resembled those observed in saltwater shells, which result from the burrowing actions of parasites. Thus, the bead nuclei were likely fashioned from saltwater shells rather than the usual freshwater nuclei employed. Nonetheless, it was impossible to determine the nature of the shell beads without destructive testing. Microradiography examination proved the bead nuclei were not pre-drilled, a characteristic often observed in freshwater nuclei used to culture freshwater pearls (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. 23–25) and typically encountered by GIA during testing. While pearls cultured with two bead nuclei are relatively uncommon, their existence has been acknowledged in the literature (Fall 1993 Lab Notes, pp. 202–203). The twin bead structure clearly influenced the appearance of these pearls and resulted in some pleasing baroque shapes.

Figure 4. Artificial material was observed filling and masking surface blemishes on some of the pearls in the necklace. Fields of view 5.68 mm (left) and 3.74 mm (right). Photos by Sharon Tsz Huen Wu.
Finally, upon closer examination, a “glittery” grainy material was observed on the pits and blemishes of several pearls (figure 4). This resembled the essence d’orient applied on the surface of some imitation pearls. Raman analysis of this material yielded a number of peaks (e.g., 634–639 cm–1 and 1604 cm–1) that matched, to some degree, the peaks of the filling material described in an earlier reference (Winter 2017 GNI, pp. 482–484).
While the GIA laboratory examines pearl strands on a daily basis, we seldom encounter one submission possessing several interesting features such as the twin bead structure, reddish orange optical X-ray fluorescence, and filled surface blemishes. It is important for gemologists to always stay alert to the surprises they might find when examining pearls. Source: GIA @topic:5


Title: Two Foraminifera-Like Objects Found in a Natural Saltwater Pearl Abstract: Figure 1. The 1.57 ct brown nacreous pearl measuring 11.06 × 9.15 × 7.20 mm. Photo by Tony Leung.
GIA’s Hong Kong laboratory recently received a brown nacreous pearl weighing 1.57 ct and measuring 11.06 × 9.15 × 7.20 mm (figure 1). It had a baroque shape and exhibited a soft luster with an unaltered surface. Despite its size, the pearl felt relatively lightweight, indicating the possibility of a hollow or partially hollow internal structure. Viewed under 40× magnification, the surface displayed overlapping nacre platelets in a spiral pattern, similar to that observed in pearls produced by Pteria species mollusks (L. Kiefert et al., “Cultured pearls from the Gulf of California, Mexico,” Spring 2004 G&G, pp. 26–39).
The sample exhibited the typical brownish surface tint of pearls produced by the Pteria mollusk species. Its ultraviolet/visible spectrum showed the characteristic reflectance features of naturally colored pearls formed in this mollusk, with identifiable absorptions at 405 and 495 nm (S. Karampelas et al., “Spectral differentiation of natural-color saltwater cultured pearls from Pinctada margaritifera and Pteria sterna,” Summer 2011 G&G, p. 117). Under long-wave UV radiation, the pearl also displayed moderate red fluorescence, a reaction linked to a type of porphyrin pigment found in pearls originating from the Pteria species (Kiefert et al., 2004). Energy-dispersive X-ray fluorescence analysis showed no traces of manganese and 1150 ppm of strontium, confirming its saltwater origin.

Figure 2. Real-time microradiographs showing the overall internal structure of the pearl (left) and greater detail of the foreign materials (right).
Real-time microradiography revealed a fascinating internal structure (figure 2). A large central void, composed of light and dark gray areas associated with the presence of organic matter, occupied almost the entire interior of the pearl, which explained the lighter than expected heft. Surrounding the void, a few distinct growth arcs were observed, following the outline of the pearl’s shape—a typical feature seen in natural pearls. In addition, two intriguing foreign materials were trapped within the inner wall of the light gray organic-rich area of the void.

Figure 3. μ-CT images revealed more details of the foraminifera-like spheres. Both consisted of a radiating structure that extended from an empty core.
Further analysis via X-ray computed microtomography (μ-CT) imaging revealed the porous nature of these two materials. Resembling foraminifera, a marine micro-skeleton member of a phylum of amoeboid protists, they consisted of radial structures extending from the center of empty cores (figure 3). The pair of near-spherical objects measured 1.50 × 1.25 mm and 1.53 × 1.33 mm, respectively, and appeared to be separate entities while sharing a homogeneous formation. The pearl’s structure was judged to be natural due to the appearance of the natural-looking void, which consisted of a flowy outline, and the presence of the foraminifera-like entities. It is worth noting that most cultured pearls from the Pteria species available in the market are bead cultured pearls. Non-bead cultured “keshi” Pteria pearls are normally of smaller sizes and distinguishable internal structures.
GIA has received numerous pearl submissions in the past with interesting internal structures related to foreign materials. In fact, the skeletal composition of the foreign material observed looked exceedingly similar to that found in a natural pearl examined by GIA’s Bangkok laboratory in 2015 (Winter 2015 Lab Notes, pp. 434–435). However, this pearl stands out for the presence of paired foraminifera-like spheres. No two pearls are the same, and it is always rewarding when advanced testing reveals such captivating features. Source: GIA @topic:5


Title: An Environmental, Social, and Governance Assessment of Marine Pearl Farming Abstract: Figure 1. Pearl diver collecting shells from the wild. Photo courtesy of Pearls of Australia: Cygnet Bay Pearl Farm, Western Australia.
Farming pearl oysters is an important economic activity that, when done sustainably, can also provide valuable environmental and social benefits. To gain an evidence-based understanding of the sustainability challenges and opportunities facing marine pearl farming and their intersection with environmental, social, and corporate governance (ESG), The Nature Conservancy (TNC), a U.S.-based nonprofit, conducted an ESG assessment of an Australian pearl farm. This pilot project was intended to guide the development of a sector-wide ESG and sustainability assessment framework. The project was supported and funded by GIA as part of its global effort focused on education and the promotion of responsible practices.
Pearl oysters filter water at rates that are often higher than those reported for other oyster species. This filtration process contributes to waste treatment through the uptake of not only nutrients (nitrogen and phosphorus) but also heavy metals (S. Gifford et al., “Quantification of in situ nutrient and heavy metal remediation by a small pearl oyster (Pinctada imbricata) farm at Port Stephens, Australia,” Marine Pollution Bulletin, Vol. 50, No. 4, pp. 417–422; L.T. Barrett et al., “Sustainable growth of non-fed aquaculture can generate valuable ecosystem benefits,” Ecosystem Services, Vol. 53, 2022, article no. 101396). Pearl oysters are hung in baskets suspended from long lines, and these structures in which they are farmed provide habitat for a variety of fish and invertebrates (S.J. Theuerkauf et al., “Habitat value of bivalve shellfish and seaweed aquaculture for fish and invertebrates: Pathways, synthesis and next steps,” Reviews in Aquaculture, Vol. 14, No. 1, 2022, pp. 54–72). If the negative impacts of pearl farming can be mitigated and effective sustainability strategies implemented through waste reduction, recovery and reuse, disease mitigation, and avoidance of overstocking, pearl farming could significantly benefit regional economies and local marine environments.
TNC’s 2019 report titled Towards a Blue Revolution provided comprehensive guidance for evaluating critical aquaculture systems. Since the report’s publication, TNC has built a science-based tool to assess industry and company operations. This tool takes into account factors related to the natural environment as well as the inherent and unique characteristics of a sector or company’s operations. The tool has been designed to consider environmental data and the health of local ecosystems, enabling the identification of potential environmental benefits via restorative aquaculture, which has the potential to generate a net positive ecosystem outcome. This approach sets it apart from other sustainability assessment frameworks, risk assessments, and life cycle assessment methodologies.

Figure 2. The pearl oysters are partially opened to allow seeding. Photo courtesy of Pearls of Australia: Cygnet Bay Pearl Farm, Western Australia.

Figure 3. Seeding Pinctada maxima pearl shell. Photo courtesy of Pearls of Australia: Cygnet Bay Pearl Farm, Western Australia.
Between February and May 2023, the assessment was conducted on Cygnet Bay Pearl Farm (CBPF; see figures 1–3), a company that produces pearls from Pinctada maxima north of Broome, Western Australia, using both wild capture and hatchery operations. CBPF is an operation of Pearls of Australia (PoA). Using the TNC framework, a number of overarching factors were assessed:

Company capacity, ethics, and management measures
Impacts on wild stocks from source of stock, hatchery escapes/interbreeding, and macrofauna interactions
Reliance on added feed and chemicals
Habitat impacts
Water column effects (e.g., temperature, salinity, light penetration, and chemical characteristics of seawater at different depths)
Disease
Use of resources: fresh water, land, and energy

The assessment showed that CBPF meets or exceeds all essential requirements within the ESG framework, including the company capacity, ethics, and management metrics. The company has no compliance issues associated with sustainability metrics, and an internal management team oversees sustainability topics and implementation. CBPF adheres to the Pearling Environmental Code of Conduct, developed by Australia’s Pearl Producers Association in 2002 and updated in 2007. The farm has Marine Stewardship Council certification, meeting independent, third-party ecological sustainability standards. It operates within a country that has an effective governance, legal, and enforcement system in place to manage the industry into the future.
Regarding the social component of ESG, CBPF forms part of the Banararr Steering Committee (BSC) of the Bardi people, the traditional owners of the area. The BSC’s role is to establish a positive relationship between CBPF and the Bardi traditional owners. Any amendment, use, or development of the area is discussed by the BSC together with relevant topics affecting the community at large, including school, transport, and fishing. Dedicated cultural heritage tours managed by Bardi people form part of the ecotourism offered at Cygnet Bay Pearl Farm. CBPF is active in research, housing the Kimberley Marine Research Station, and parent company PoA currently partners with the Marine Bioproducts Cooperative Research Centre. This research focuses on better understanding the implications and potential positive effects on fish and invertebrates that grow naturally on PoA farms.
CBPF could already be providing environmental benefits to the surrounding area through restorative aquaculture practices. Based on a general understanding of ecosystem services associated with oyster aquaculture, CBPF does meet the criteria for restorative outcomes, such as increased cycling of water and nutrients and providing habitat to other species. However, the extent to which these ecosystem services positively impact broader environmental outcomes remains unknown, in part because of the limited understanding of anthropogenic effects on water quality and habitat loss in the area.
Overall, the assessment provided an effective means to evaluate CBPF for its management and approach to ESG, the extent to which cultural communities are considered, the company’s engagement with voluntary certification and codes of practices, and its awareness of key environmental risks and negative impacts as well as positive impacts.
At the same time, additional needs for TNC’s ESG Assessment Framework have been identified. Brood stock sourcing and handling, biosecurity, and genetic risks are all areas that require additional research. One hundred percent utilization of the oysters farmed should be an explicit goal and assessment factor. The assessment should also consider the legacy effects of aquaculture equipment (e.g., recovery, reuse, and recycling), as well as the origin and species status of shells utilized to manufacture nuclei. Once these considerations are addressed, the TNC’s ESG Assessment Framework should provide an effective sector-wide approach. Source: GIA @topic:5


Title: Calcite Present in a Pearl from Pinctada maculata Abstract: Figure 1. The white and cream non-nacreous pearl weighing 0.29 ct and measuring 3.75 × 3.55 mm. Photo by Gaurav Bera.
Pinctada maculata pearls, also known in the trade as “pipi pearls,” form in shells considered to be the smallest of all the Pinctada species. The shell size ranges from 2 to 6 cm and produces pearls ranging from 1 to 4 mm. However, some rare examples may reach up to 9 mm (Spring 2014 GNI, pp. 89–90). Most pearls from this mollusk exhibit a yellow to “golden” color range, yet some are white to cream, orange, and gray. Round to near-round pearls are quite typical of the species, but other shapes may be found, as with all pearls (N. Nilpetploy et al., “The gemological characteristics of pipi pearls reportedly from Pinctada maculata,” Winter 2018 G&G, pp. 418–427). They are distributed throughout French Polynesia and the Cook Islands and found in shallow waters and depths up to 20 meters. GIA’s Mumbai laboratory had the opportunity to examine a quantity of these pearls, which were reportedly sourced from known divers who fished them from wild P. maculata mollusks off the Cook Islands. The parcel contained 306 natural pearls of various sizes and shapes, with measurements ranging from 2.87 × 2.69 × 2.55 mm to 8.34 × 3.25 mm.

Figure 2. Left: Cellular calcite structure; field of view 0.5 mm. Right: Aragonite platy surface structure; field of view 0.8 mm. Photomicrographs by Pfokreni Nipuni.

Figure 3. The Raman spectra showed peaks at 280 and 712 cm–1 indicative of calcite (spots 1 and 2) and typical aragonite features at 701, 704, and 1085 cm–1 (spot 3).
Real-time microradiography (RTX) showed a variety of internal structures expected for natural pearls. Externally, most samples showed the typical nacreous overlapping aragonite platelets (platy structure) and surfaces that ranged from clean to moderately blemished. However, one near-oval, bicolor white and cream pearl, weighing 0.29 ct and measuring 3.75 × 3.55 mm (figure 1), revealed a very interesting surface structure under 40× magnification. The top part of the pearl exhibited a mosaic, or network of columnar calcite structures in a cellular form (hexagonal and clustered), creating an uneven surface. This was similar to the appearance of non-nacreous pen pearls (N. Sturman et al., “Observations on pearls reportedly from the Pinnidae family (pen pearls),” Fall 2014 G&G, pp. 202–215). The bottom part had a combination of both: areas of nacreous overlapping aragonite platelets (the circular ring-like area around the base) and areas of columnar calcite structure (figure 2). The surface was unique among those observed in the lot, as it exhibited both polymorph forms of calcium carbonate (aragonite and calcite). To confirm the non-nacreous cellular areas observed, Raman analysis using a 514 nm laser excitation was carried out on three spots of the pearl’s surface (spots 1 and 2 with cellular structure and spot 3 with platy structure). Spots 1 and 2 showed peaks at 280 and 712 cm–1, respectively, indicative of calcite. Spot 3 showed a doublet at 701 and 704 cm–1 and a peak at 1085 cm–1, both characteristic features of aragonite (figure 3).

Figure 4. Left: RTX image revealing the calcitic nature of the pearl. Right: μ-CT scans showed a small core with a large acicular structure covering the entire area.
RTX imaging revealed an organic-rich fine acicular feature with no central core, associated with some concentric growth arcs (figure 4, left). X-ray computed microtomography (μ-CT) showed a large central fine acicular feature with a small core showing its calcitic nature, surrounded with thick, dense organic-rich concentric growth arcs (figure 4, right). The internal structure of the pearl matched with the expected columnar structure observed on the surface, as noted in previous research reports.
Energy-dispersive X-ray fluorescence spectrometry revealed a low manganese level of 16 ppm and a higher strontium level of 1286 ppm. Optical X-ray fluorescence was inert, and both results are characteristic of the saltwater environment in which the pearl formed. The pearl showed a moderate bluish green reaction under long-wave UV radiation and a much weaker bluish green reaction under short-wave UV. It was also examined by the ultra-short UV wavelength (230 nm) of the DiamondView, which revealed a clear bluish reaction with fine cellular hexagonal columnar features typically indicative of calcite.
Spectroscopic examination confirmed the presence of both calcite and aragonite. The top and bottom portions of this P. maculata pearl exhibited a combination of calcite and aragonite surface features aligned parallel to each other. Such external features are not typically observed in pearls from this mollusk, based on the extensive samples GIA has examined globally, which makes this pearl rare and interesting despite its lack of visual appeal. Source: GIA @topic:5


Title: Fine Linear Structures in Non-Bead Cultured Pearls Abstract: Four non-bead cultured pearls (samples 1–4, left to right) weighing 0.22 to 4.84 ct. Photo by Gaurav Bera.
Saltwater non-bead cultured (NBC) pearls are defined by the World Jewellery Confederation (CIBJO) as those without an internal bead nucleus that have “formed accidentally or intentionally by human intervention in marine pearl oysters.” These are commonly referred to as “keshi” pearls in the trade. GIA’s Mumbai laboratory has received many pearl submissions that revealed internal structures typical of NBC pearls such as large voids, elongated linear structures, and some with loose concentric “gaps.” However, a recent submission of 23 loose pearls for pearl sorting service proved quite challenging to identify. Externally, all of them looked similar, with a white to light cream color and a medium to high luster. Some possessed a few surface blemishes, but on the whole they were quite clean and appeared cultured.
A majority of the pearls in the lot exhibited concave bases, while a few showed bases with concentric, graduating white to cream-colored rings, with distinct central white frosty patches which were part of the inner subsurface nacreous layers. Four pearls revealing different forms of linear structures were selected from this lot. All were white and button shaped, with sizes ranging from 3.24 × 2.55 mm to 10.33 × 6.84 mm (see above). Externally, all their surfaces exhibited typical nacreous overlapping aragonite platelets, with a fingerprint-like pattern when viewed under 40× magnification.
Energy-dispersive X-ray fluorescence spectrometry on the four pearls revealed low manganese levels ranging between 12.60 and 41.10 ppm and high strontium levels between 1767 and 2883 ppm. Additionally, optical X-ray fluorescence analysis yielded an inert reaction, thus confirming their saltwater origin. The pearls showed a moderate bluish green reaction when viewed under long-wave ultraviolet radiation and a weaker bluish green reaction under short-wave ultraviolet radiation. Raman analysis using 514 nm laser excitation showed a doublet at 702 and 705 cm–1 and peaks at 1085 and 1463 cm–1 indicative of aragonite.

Real-time microradiography (RTX) and X-ray computed microtomography (μ-CT) analysis revealed internal structures that were not straightforward and required more work to reach conclusive results. RTX imaging of pearl 1 showed a prominent, very fine central linear feature horizontal to the base (table 1, row 1). Analysis with μ-CT revealed a more obvious linear feature showing that it was unaligned with the other growth arcs that generally followed the shape of the pearl. This structure was observed in most of the samples in the submitted lot. Externally, a small white frosty central spot was visible on the concave base surrounded by graduating circular rings.
RTX images of pearl 2 revealed a small circular light gray core associated with undefined gray arcs curving along the core in a distorted pattern (table 1, row 2). Moreover, only a couple of weak growth arcs were observed in the outer nacre layers. The structure was very similar to those observed in some natural pearls with small dense cores, making it inconclusive (A. Homkrajae et al., “Internal structures of known Pinctada maxima pearls: Cultured pearls from operated marine mollusks,” Fall 2021 G&G, pp. 186–205). Further μ-CT analysis helped define the main feature, a short and fine linear structure accompanied by a minute void-like feature.
RTX images for pearl 3 revealed a medium-size button-shaped central organic-rich core, which was radiotranslucent and had a thin gray outline (table 1, row 3). This was surrounded by numerous fine growth arcs that followed the shape of the core. Although this organic-rich core looked quite natural from the RTX images, μ-CT images revealed a short linear feature in the center of the core, suggesting an NBC pearl.
The largest sample, pearl 4, had been partially drilled, and the drill hole was quite large (table 1, row 4). It was unlike the thinner and shorter drill holes often used for weight retention in natural pearls. While the choice of drill hole thickness is not decisive evidence on its own, it may be a useful indicator (Spring 1986 Lab Notes, pp. 51–52; Summer 1986 Lab Notes, p. 111). Externally, the pearl had a rounded base and a circled circumference with multiple deep indentations associated with the circled grooves. The RTX images showed minute metal remnants (visible as radiopaque white specks) within the drill hole and extensive curved growth arcs throughout the pearl, with additional arcs located on adjacent boundaries. The pearl showed minimal tight growth structure, and its external appearance aroused suspicion. Further examination via μ-CT analysis revealed a small linear feature that had been partially removed by the drilling. Reaching a conclusion would be very challenging, if not impossible, using RTX analysis alone.
Given the volume of button-shaped pearls the Mumbai laboratory has been testing, it is quite evident that large quantities of such pearls are circulating in the market. These pearls mostly have smooth surfaces and high untreated luster. The linear features could not be identified in all the pearls using RTX alone due to a number of factors including size, appearance, radiotranslucency, and orientation. It is not difficult to remove minute linear structures by drilling, and such pearls could easily be passed off as natural due to the presence of fine growth features around the center. But with the availability of advanced technology, especially μ-CT imaging, remnants of the linear structure were evident in certain orientations. In some cases, with the proper alignment of the drill hole, such small linear structures may also be visible in the RTX images. This requires considerable skill and patience to align, starting from the thickest direction first with respect to the shape of the pearl and then repositioning the same pearl 90° in the profile view. Therefore, it may be risky to rely on RTX results alone (S. Karampelas et al., “X-ray computed microtomography applied to pearls: Methodology, advantages, and limitations,” Summer 2010 G&G, pp. 122–127).
By analyzing these challenging internal structures using modern equipment, GIA and other laboratories aim to protect consumers by creating awareness of them and minimizing the chances of misidentification. Source: GIA @topic:5


Title: A Fascinating Large South Sea Bead Cultured Pearl Abstract: Figure 1. The large round bead cultured pearl weighing 54.96 ct and measuring 19.90 × 19.53 mm. Photo by Gaurav Bera.
A recent noteworthy submission to GIA’s Mumbai laboratory contained a loose round, undrilled white pearl with strong orient, weighing 54.96 ct and measuring 19.90 × 19.53 mm (figure 1). Externally the pearl had a smooth, blemish-free surface and exhibited a homogeneous uniform color with a high luster. When viewed under 40× magnification, large and evenly spaced overlapping aragonite platelets were visible which helped account for the silky reflection on the surface. X-ray fluorescence (XRF) analysis gave a relatively inert reaction. Chemical analysis using energy-dispersive X-ray fluorescence spectrometry was performed on two surface areas. The data collected showed manganese levels on both areas below the detection level of the instrument and higher strontium levels of 1162 and 1163 ppm, confirming the pearl formed in a saltwater environment. A moderate greenish yellow reaction was observed under long-wave ultraviolet radiation, and a much weaker greenish yellow reaction was noted under short-wave UV.

Figure 2. RTX images revealing the pearl’s internal structure. Left: Diameter of the bead in four directions. Right: The size of the nacre thickness measurements around the bead from its demarcation up to the outer nacre in four directions.
Due to the pearl’s large size, it was quite intriguing to see the growth structure revealed from within. Real-time microradiography (RTX) imaging showed an extremely small bead nucleus together with distinct growth arcs flowing in an even pattern around the nucleus proving it to be a bead cultured (BC) pearl. The exceptional thickness of the nacre growth around the bead was particularly notable (figure 2) (L.M. Otter et al., “A look inside a remarkably large beaded South Sea cultured pearl,” Spring 2014 G&G, pp. 58–62). The size of the bead and the nacre thickness were measured using an option available on the RTX instrument, resulting in a reading of 6.122 mm for the thickest part of the bead and a range of 5.987 to 6.283 mm, in four different directions, for the overlying nacre. These measurements indicated a composition of more than 96% nacre and less than 4% bead nucleus by volume.

Figure 3. X-ray fluorescence reaction comparison for a freshwater non-bead cultured pearl (A), a saltwater bead cultured pearl with thin to medium nacre thickness (B), and the examined pearl with relatively thick nacre (C). Photos by Gaurav Bera.
The majority of beads used in the cultivation process of BC pearls are produced from freshwater mollusk shell (Unionidae) collected in the United States (A. Homkrajae et al., “Internal structures of known Pinctada maxima pearls: Cultured pearls from operated marine mollusks,” Fall 2021 G&G, pp. 186–205). Due to the high levels of manganese present in freshwater mollusks, such BC pearls would emit a weak or moderate yellowish green fluorescence when subjected to XRF analysis. This reaction is normally based on the size of bead nuclei used in the cultivation process and the thickness of the surrounding nacre. Hence, the reaction observed via XRF for the pearl was relatively weak due to the thickness of its nacre overgrowth (figure 3) (S. Karampelas et al., “Chemical characteristics of freshwater and saltwater natural and cultured pearls from different bivalves,” Minerals, Vol. 9, No. 6, 2019, article no. 357). Taking all these factors into consideration—external appearance, dimensions, size of the bead nucleus, nacre thickness measurements, and chemistry data—the pearl was classified as a BC pearl produced from the Pinctada maxima species.
Over the decades, South Sea BC pearls have played an important part in the global pearl trade. Larger pearls, some more than 20 mm, were also produced, but these are very rare even with today’s modern farming methods. Their uniquely large size, silky luster, and greater nacre thickness compared with BC pearls from other mollusks make them more attractive and durable. This has allowed them to establish a prominent position in the cultured pearl value chain as the primary choice of consumers looking for large white to cream, or “golden” BC pearls. As a result, they have been used by renowned jewelry designers in their exclusive collections. GIA continues to test numerous South Sea cultured pearls, and this unique submission to the Mumbai laboratory was particularly notable for its size and fine quality. Source: GIA @topic:5


Title: Heart-Shaped Golden South Sea Cultured Pearl Abstract: Figure 1. A heart-shaped golden South Sea pearl pendant measuring 17.78 × 11.65 × 9.07 mm and weighing 1.93 g (including the 18K yellow metal findings). Photo by Sood Oil (Judy) Chia.
The heart shape has been a worldwide symbol of love and romance for centuries. GIA’s New York laboratory recently received a golden-colored heart-shaped pearl pendant that drew our attention. The pearl was reportedly produced in the Philippines, which is a major source of golden South Sea cultured pearls. Upon routine gemological and advanced instrumental examination—including microradiography, ultraviolet/visible spectroscopy, manganese and strontium contents from energy-dispersive X-ray fluorescence, and reaction to long-wave UV—we concluded that it was an atypical bead cultured pearl from the Pinctada maxima species, commonly known in the trade as a South Sea cultured pearl (figure 1), and its heart shape and golden color were entirely natural.

Figure 2. X-ray images from RTX (left) and CT (right) show the demarcation of a heart-shaped bead nucleus with an average nacre thickness of 0.80 mm.
Unlike the traditional bead cultured pearls typically nucleated with spherical shell bead nuclei, a heart-shaped bead nucleus was used in this pearl to achieve its unique shape. Hence, it was described as an “atypical bead” cultured pearl (aBCP) according to GIA’s pearl identification terminology. Real-time microradiography (RTX) and X-ray computed microtomography (CT) clearly revealed the internal structure of a heart-shaped bead nucleus (figure 2). The nacre coverage, averaging 0.80 mm thick, was evenly distributed all around the nucleus, demonstrating that the heart shape of the pearl was consistent with the shape of the nucleus. Magnification revealed no signs of surface working or treatment, suggesting the pearl was in its original form after harvest. It displayed a strong orangy yellow color that is highly sought after among South Sea pearls. Ultraviolet/visible reflectance and photoluminescence spectroscopy further confirmed its natural color origin (C. Zhou et al., “Update on the identification of dye treatment in yellow or ‘golden’ cultured pearls,” Winter 2012 G&G, pp. 284–291).
Although this was not the first time a heart-shaped pearl has been examined in the lab, it is very rare to see a whole pearl with such a perfect non-round cultured shape. Previous submissions have either been identified as mabe pearls (assembled cultured blisters) or have had poorly defined heart shapes. Mabe pearls are not considered whole pearls and often possess a thin nacre dome top (Fall 2021 Gem News International, pp. 277–279). Due to the thin nacre, their shape is easier to control. Therefore, fancy-shaped nuclei are commonly used in mabe pearls.
Many atypical bead cultured pearls have been studied and examined over the years at GIA (“Atypical ‘beading’ in the production of cultured pearls from Australian Pinctada maxima,” GIA Research News, February 13, 2017; Fall 2022 Gem News International, pp. 378–380). However, the majority of the end products are very different from the original shape of the nuclei. This remarkable use of an atypical bead nucleus to achieve a perfect shape in a cultured pearl suggests recent improvements in pearl culturing techniques. Source: GIA @topic:5


Title: Freshwater Pearls, Blister and Loose, with Their Host Shells Abstract: Figure 1. Three freshwater pearls attached to their host shells. Left to right: A blister pearl measuring approximately 37.45 × 27.48 mm, a loose wing pearl measuring 35.82 × 9.37 × 5.94 mm and weighing 10.60 ct, and a blister pearl measuring approximately 23.60 × 19.49 mm. Photo by Sood Oil (Judy) Chia; specimens courtesy of Mississippi River Pearl Jewelry Co. LLC.
GIA occasionally receives blister pearls attached to their host shells for identification (Winter 2015 Lab Notes, pp. 432–434; Summer 2017 Lab Notes, pp. 231–232), which can provide helpful information on the overall growth conditions and the mollusk species. Recently the New York laboratory had an opportunity to study three freshwater specimens: two blister pearls still attached to their shells, and one loose “wing” pearl that was reportedly found in the shell with which it was submitted (figure 1).
While approximately 1,000 species of freshwater mussels have been identified worldwide, the United States alone is said to host about 300 species, compared to 96 species in Africa, 60 in China, and 12 in Europe (Virginia Department of Game and Inland Fisheries, 2018, https://www.dgif.virginia.gov/wildlife/freshwater-mussels/). The number of U.S. species shows the spectacular diversity of its freshwater resources. Hence, it proves how difficult it can be to apply correct zoological names to specific shells. However, experienced local fishermen who harvest the mussels are often the source of helpful information (T. Hsu et al., “Freshwater pearling in Tennessee,” 2016). The owner claimed that the loose wing-shaped pearl (figure 1, center) was found in a Potamilus purpuratus “Bluefer” mussel in a U.S. river. Bluefer mussels exhibit a pinkish purple to deep purple nacre lining and can produce pearls of a similar color range. Energy-dispersive X-ray fluorescence (EDXRF) spectrometry confirmed that it originated from a freshwater environment, based on its chemistry result of more than 1000 ppmw manganese. Freshwater pearls usually show higher than 100 ppmw manganese content. Real-time X-ray microradiography (RTX) revealed a natural growth structure, while Raman spectroscopy detected aragonite and polyenic peaks, the latter indicating the presence of natural coloring pigments (S. Karampelas et al., “Role of polyenes in the coloration of cultured freshwater pearls,” European Journal of Mineralogy, Vol. 21, 2009, pp. 85–97). This specimen also displayed the characteristic elongated, flat, and slightly curved shape characteristic of wing pearls that, as the name implies, resembles the shape of a bird’s wing. Wing pearls commonly form in the hinge area within shells, and it was interesting to see a similar-sized cavity in the shell submitted with this pearl.
The other two blister pearls were also claimed to have originated from a freshwater environment, and this was confirmed by their optical X-ray fluorescence reactions. Both specimens showed a strong yellowish green luminescence under X-ray excitation, a result that agrees with pearls from a freshwater environment due to their higher manganese content (H.A. Hänni et al., “X-ray luminescence, a valuable test in pearl identification,” The Journal of Gemmology, Vol 29, No. 5/6, 2005, pp. 325–329). According to the owner, the smaller shell (figure 1, right), possibly a washboard mussel (Megalonaias nervosa), was found in a U.S. river, while the larger shell (figure 1, left) is likely a hybrid Hyriopsis mussel commonly used by cultured pearl farmers in China. Blister pearls form when a whole pearl within the connective tissue breaks through the mantle due to its size and/or weight, or for some other reason, and presses against the nacreous inner surface of the shell, where subsequent nacre deposition fuses the pearl to the shell (E. Strack, Pearls, Ruhle-Diebener-Verlag, Stuttgart, Germany, 2006, p. 124).

Figure 2. Close-up images of the freshwater blister pearls from China (left) and the United States (right) attached to their hosts. Photos by Joyce Wing Yan Ho.

Figure 3. The RTX structure of the large blister pearl (shown on the left in figures 1 and 2) revealed a void-like structure in which a near-oval feature is visible (indicated by the arrow).
The size of these two blister pearls is impressive, and both protrude conspicuously from the shell while still attached to their hosts (figure 2). The RTX results of the smaller blister pearl revealed concentric growth arcs proving its natural origin. However, the RTX results of the larger blister pearl revealed a void-like structure that may be found within natural and non-bead-cultured pearls, but a near-oval feature inside the void is uncommon in natural pearls (figure 3). GIA gemologists believe this oval feature was the triggering mechanism that likely resulted in the formation of the blister pearl. Whether this oval feature is a by-product of pearl culturing or a natural formation is hard to prove without examining the blister pearl thoroughly in other orientations, which was precluded by its size and position. While the identification of some freshwater pearls remains challenging, these known freshwater samples together with their host shells serve as useful references for laboratory gemologists. Source: GIA @topic:5


Title: Characteristics of Nuclei in Chinese Freshwater Cultured Pearls Abstract: There has been considerable debate in the gem trade concerning the nucleation procedures being used to grow large round Chinese freshwater cultured pearls (FWCPs). Of particular concern are claims that most of these cultured pearls are nucleated by reject mantle-tissue-nucleated FWCPs, and that such a product would be difficult to separate from normal tissue-nucleated cultured pearls and in some cases from natural pearls. However, field research indicates that many Chinese growers are currently using larger mussels (Hyriopsis cumingi), combined with new tissue-insertion techniques, to grow larger, better-shaped FWCPs. For this study, X-radiographs of approximately 41,000 Chinese freshwater cultured pearls from dozens of farms were examined, and 10 samples were sectioned. All showed evidence of mantle tissue nucleation only; the presence of a bead, whether shell or a tissue-nucleated FWCP, would be identifiable by distinctive features seen in the X-radiograph. Source: GIA @topic:5