Title: Pearls: Forever Fashionable Abstract: Courtesy of Atelier Marisa

                      A jewelry store’s pearl counter is a fascinating place. These enchanting gems have represented beauty and perfection ever since man discovered them in ancient times. They have been the subject of countless tales of history, beauty, myth and elegance.

The Arabian Gulf was the world’s first source of natural pearls and remained so for centuries. Natural pearls from the Gulf are notable for their transparent and high-luster nacre. Together with pearls from the Red Sea and the Strait of Manaar, they have been referred to as “oriental pearls” and are highly valued.

Part of a pearl’s appeal is its organic origins: It comes from a living animal, a mollusk. And because pearls are slightly porous, they warm up against the skin as they are worn. The wearer and the gems become one.

The exciting array of pearl choices available today can be overwhelming. When you combine the variety of colors, sizes and shapes with metals and other gemstones in rings, necklaces and earrings, the possible combinations are practically endless.

So before you set off to buy pearl jewelry, you should understand the basics. Are you looking for natural or cultured pearls? Do you know what to look for in terms of size, luster and color? What price range are you interested in? How are some pearls treated to enhance their appearance? These are all good questions to consider before you begin to shop.

A retailer who knows the types of natural and cultured pearls that are available and the factors that determine their value will be an invaluable resource to you as you explore pearls.

In the meantime, here are some basics to get you started.

Pearls are natural or cultured and grow in mollusks that can live in either saltwater or fresh water. They are made up of layers of calcium carbonate most popularly in the form of nacre, a natural substance produced by pearl oysters that coats the inside of the animal’s shell. This beautiful, lustrous nacre is the very essence of a pearl.

Natural Saltwater Pearls
Natural pearls are extremely rare. The Arabian Gulf is the most important source for natural pearls – 70-80 percent of all pearls came from there until the 1950s. The island of Bahrain was a center for trade with northwest India and what is now the modern Middle East. A 4,000-year-old pearl was uncovered in 1989, and excavations at the ancient Bahrain’s Dilmun settlement have confirmed that pearl fishing has been going on for at least 3,000 years.

Natural saltwater pearls from the Arabian Gulf come from the Pinctada radiata and Pinctada margaritifera. Persian Gulf pearls range in color from white to dark cream and tend to be more yellow than those from the Red Sea and Strait of Manaar, whose characteristic colors are very light yellow, cream and very light pink. The Red Sea also produces some pearls in darker hues that range from intense pink to light to dark violet.

Natural saltwater pearls are also found occasionally in Baja California, Venezuela, Myanmar, China, Japan, India, French Polynesia, Australia and Africa – the same regions that have cultured pearl industries.

Saltwater Cultured Pearls
If you ask someone to describe an Akoya pearl, they will most likely describe a white, round, lustrous gem cultured in Japan and China in Pinctada fucata (martensii). Most akoya cultured pearls are white or cream and some have hints of rosé (pink) or green. The akoya oyster is relatively small, so it doesn’t usually produce a cultured pearl larger than 9 mm. Natural pearls from Pinctada fucata (matensii) are extremely rare.

Tahitian cultured pearls have only been on the market since the 1970s and come in colors including eggplant purple, peacock green, metallic gray and grayish blue. The mollusk that produces them (Pinctada margaritifera) is native to French Polynesia and is farmed there and in the Cook Islands, Fiji, Australia and New Zealand.

South Sea cultured pearls come from one of the world’s largest pearl oyster (Pinctada maxima), which produces cultured pearls that can measure 15 mm or larger. They are farmed in Australia, Burma, the Philippines and Indonesia. While South Sea cultured pearls occur in other colors, silver, white and yellow (sometimes referred to as “golden”) are the most common.

Freshwater Cultured Pearls
Cultured pearl farmers in China produce the overwhelming majority of cultured freshwater pearls. These cultured pearls vary widely in color and are generally more affordable than saltwater cultured pearls. Sizes are comparable to akoya cultured pearls, with a range between 2 mm and 13 mm, although larger sizes are now available. Fascinating new cultured pearls from fire balls to soufflés have been emerging from China in a dramatic array of colors.

The chief cultured pearl-producing mussel in the U.S. is the “washboard” M. nervosa. Only a small fraction of the total number of freshwater cultured pearls produced come from the U.S.

What to look for when picking out pearls
GIA, the world’s foremost authority on diamonds and gems, created a pearl description system, in order to evaluate the quality of pearls. GIA’s 7 Value Factors include Size, Shape, Color, Luster, Surface, and Nacre. Be sure to ask your sales associate to go through these with you.

Size: As with other gems, a larger pearl (measured in millimeters) is typically more valuable. The larger the pearl, the more rare and costly it tends to be. But fine quality pearls can be small, and low quality pearls can be large, so a pearl’s ultimate worth depends on how it combines the complete mix of value factors.

Shape: While round is the most familiar shape, pearls come in a parade of forms (round, near round, oval, button, drop, semi-baroque, baroque). No matter what its shape, if a pearl is or symmetrical, it will be more valuable than one that’s irregular.

Color: A pearl’s color is a combination of its dominant bodycolor, overtone, the subtle colours that seem to come from within the pearl, and orient, the “play of color” you see when the pearl moves.. Cultured pearls display a broad palette of subtle hues, ranging from warm (yellow, orange and pink) to cool (blue, green and violet).

Luster: The intensity of light reflected from or just below the surface of the pearl, its luster, contributes the most to the beauty of a pearl. The effect is an inner glow from the heart of the gem. A pearl with excellent luster will look bright and shiny, while one with poor luster is dull and far less valuable. Fine akoyas tend to display a bright, mirror-like gloss. Other pearls tend to feature a softer, satiny luster.

Surface: A completely clean pearl is a rare treasure. Since rarity influences value, the prices of such pearls run extremely high. The number, nature, and location of surface characteristics (abrasions, bumps, chips, cracks, etc.) can affect the value of any pearl. Numerous or severe surface irregularities – such as chips or gaps – can threaten the durability of the pearl and cause it to break or peel and considerably lower its quality and value. If a surface characteristic is minor and located near a pearl’s drill hole, where it’s less noticeable, it will detract less from the pearl’s appearance and ultimate value.

Other value factors can minimize the effect of surface characteristics on a pearl’s worth. If the pearl is large and highly lustrous, for example, these pluses can outweigh a slight surface characteristic or two. In fact, excellent luster makes some surface characteristics less noticeable.

Nacre: Nacre is the very essence of the pearl itself and nacre thickness does affect the value. Quality cultured pearls have ample thickness to allow the pearl to display its beauty.

Matching: The uniformity of the appearance of pearls in strands and multi-pearl pieces is called matching.

How to Care for Pearls
Now that you’ve gotten your pearls, you should know a few things about taking care of them.

To retain their beauty, they need a certain amount of moisture, which is why you should avoid storing pearls in an airtight or overly dry environment, such as a bank safety deposit box. The human body conveniently provides just the right amount of moisture. Worn often and properly cared for, pearls can look as good in 50 years as they did the day they left the store.

Pearls are not the most durable of gems. Most everyday items at home and in the office are tougher than pearls, so careless contact can cause damage them over time. Chemicals are the primary threat. Perfume, makeup and hairspray contain ingredients that can eat away the nacre, permanently dulling it. Many cleaning products contain chemicals such as ammonia and chlorine, which can pit gold alloys and quickly damage pearls. Chlorinated swimming pool water is also hazardous. Avoid wearing pearl jewellery when cleaning the house or doing yard work.

The best way to clean your pearls is with a soft damp cloth, ideally after each time you wear them.

Are you ready to learn more?
Consider taking a course to gain a deeper understanding of this fascinating gem. GIA offers an online pearl course in its gemmology eLearning curriculum that you can take from the comfort of your home. It’s a fascinating look at the world of pearls, including their origin, how they get to market, and the GIA 7 Value Factors used to describe their quality. Or, you can choose to take a one-day instructor-led GIA Pearl Grading class where you’ll learn to evaluate the quality of freshwater, South Sea and Tahitian pearls. Source: GIA @topic:5


Title: Cultured Pearl Market Update Abstract: Figure 1. The range of necklaces at Mastoloni’s AGTA booth included innovative blends of different cultured pearl types. Photo by Eric Welch; courtesy of Mastoloni Pearls.

At the 2017 AGTA show, Fran Mastoloni (Mastoloni Pearls, New York City) provided a cultured pearl market update. Mastoloni is a 30-year veteran of the Tucson show and well positioned to place the ups and downs of demand in context. There is a real desire for cultured pearls, he says, but people have moved away from the traditional white necklace. Partly this is because cultured pearl sources have become much more diverse in recent years, with French Polynesia, Australia, the Philippines, Indonesia, and China contributing a diverse array of cultured pearl types, shapes, sizes, and colors (figure 1).

Mastoloni’s clients are seeking—and selecting—something different. “They all want a unique necklace,” he says. And since the second quarter of 2016, he’s seen demand pick up considerably. Most clients don’t want to spend a fortune, but they do want the piece they choose to be unique and individual. His job is to create cultured pearl necklaces that meet their needs.

	Fran Mastoloni – Mastoloni Pearls

In this interview, Fran Mastoloni updates us on trends in cultured pearl supply and customer demand. He presents some of the most attractive—and successful—necklace designs and provides insight into which styles people choose and why.
To demonstrate, Mastoloni showed us his “Fantasy” necklace: a standard-length strand combining South Sea and Tahitian cultured pearls with lighter gold ones from Indonesia. This blends a repeating pattern of large (up to 16 mm) eye-catching, semi-baroque pearls with smaller examples—down to 8 mm—to create a large, mixed look. The use of light and dark pearls also confers the ability to use the piece on a variety of clothing colors for day or night use, he added, so it’s very versatile. He added that products must also appeal to female self-purchasers, so the retail price point—less than $2,000 per strand—is an important consideration. This is a very important—if not the most important—market segment for him today.

Mastoloni showed us another successful cultured pearl line for the company, which he dubbed the “Cocktail” necklace (figure 2). It combines Philippine gold pearls, white Australian South Sea, and lighter Tahitian pearls to create a long necklace that can be draped twice. Again, every necklace is individual, so that a customer can “key into” an individual pearl—maybe a large South Sea or Tahitian—and identify that necklace as unique. Examples like these, he explained, transform the concept of what a cultured pearl necklace might be.

Figure 2. The “Cocktail” necklace features a combination of differently sized round cultured pearls: darker Tahitian, golden Philippine, and white Australian South Sea. Photo by Eric Welch; courtesy of Mastoloni Pearls.
Customers are similarly drawn to baroque pearls for their uniqueness. Mastoloni used a variation of the “Cocktail” necklace to illustrate the point, this time with baroque pearls ranging from 16–17 mm plus down to 9 mm. The organic shapes bring texture and movement to the piece and “make it fun.”

Figure 3. This necklace features 14 mm round Tahitian cultured pearls in the front and 9 mm South Sea “keshi.” Photo by Eric Welch; courtesy of Mastoloni Pearls.
The next necklace he showed us blended 9 mm baroque white South Sea “keshi” pearls with 14 mm dark Tahitian round cultured pearls, creating two transitions: from light to dark and from organic shapes to regular, round ones (figure 3). A customer might own all three of these necklaces, he said, and use them for different occasions.

Also popular are variations on the wave necklace, which blends a uniform strand of round white Japanese akoya cultured pearls with “waves” of graduated silvery black Tahitian cultured pearls that swell and pinch out against the white of the akoyas. The mix of the different cultured pearl types working together is what makes these designs so successful. They’re the kind of “fashion-forward” pieces that stylish but price-conscious consumers pick out, he says.

Of course, sourcing pearls for all these necklaces is always a challenge for Mastoloni. One of his key considerations is maintaining standards. For the “Cocktail” necklaces he has to source pearls of the same tone, color saturation, and luster. You just can’t throw pearls together and expect them to look good, he explained. It requires an understanding of the product along with consistency in both quality and look—as well as an enormous amount of pearls.

Mastoloni asked us to look at professional women of power on television, who frequently wear significant pearl necklaces. Their choice might be a necklace combining different pearl colors, or a uniform one with large round white South Sea or Tahitian cultured pearls. Fine pearls can be worn in the boardroom or at social gatherings—they show that the wearer “has arrived.” No other jewelry is as versatile.

Mastoloni noted that the supply of Tahitian cultured pearls has changed. Although there looks to be a good variety of subtle colors, he’s not seeing the same wide range of colors as 10–15 years ago. This appears to be because the culturing process is improving and there is more control over color consistency. This is better from the point of view of investors, because consistent colored pearls are easier to match and sell. As a result, those investing in pearl cultivation find it easier to recoup their expenses.

Next, he showed us single pearls and collection pieces, starting with a 23.3 × 28.6 mm Australian baroque South Sea pearl that was solid and unblemished on all its surfaces. Single pearls like this one are unique items that a person can make their signature piece—something they wear every day.

Pairs, such as the 15.0 × 18.5 mm Tahitian cultured pearls seen in figure 4, are also perfect for unique pieces. Their light pistachio color is one of the colors Mastoloni used to love but can no longer easily obtain. Serendipitously, he found a matching-color larger drop shape measuring 16.0 × 22.7 mm to make up a trio (again, see figure 4). According to Mastoloni, the right designer could make an incredible piece out of these.

Figure 4. A pair of 15 × 18.5 mm light pistachio Tahitian cultured pearls. A matching-color
drop shape measuring 16 × 22.7 mm makes up a trio. Photo by Eric Welch; courtesy
of Mastoloni Pearls.
His next piece was a 16 × 23 mm Tahitian drop pearl with a unusual shape and excellent luster. It was a near-perfect teardrop with a very attractive slightly asymmetrical tip, shaped almost like a drop of water. It begs attention, he explains, a pearl like this could be the center of attention in a one-of-a-kind necklace. Mastoloni confirmed that such teardrop-shaped pearls are now difficult to find in Tahitian production. As pearl culturing techniques improve, drop pearls are nowhere near as desirable—or as profitable to produce—as spherical ones. Pearl farmers are more concerned with return on investment, so they are really striving to produce more round pearls. As pearl culturing methods improve, consequently, it becomes harder and harder to find nice teardrops—producers make a lot of less attractive, misshapen examples which bring down the value of the harvest.

Finally, Mastoloni showed us a top-quality pair of 15.3 mm round golden pearls. He noted that golden pearls—which are generally produced from the gold-lipped oyster in the Philippines and Indonesia—are still a good business, with much stronger demand in Asia than in the U.S., although the market probably peaked about a year ago. He notes that there might be a little oversupply in Asian markets, but he expects it to be temporary. As far as quality is concerned, Mastoloni’s advice is to look for a pearl that has a good “gold” color—he always likens it to a “ring color”—“you don’t want yellow and you don’t want green, but it’s got to have a richer gold to it,” he says. Indonesia is always going to have a steady supply of pearls, because cultivation takes place over such a large area, he says but cautions that there’s so much champagne and creamy greenish yellow production that he cannot use. He notes that their supply is getting better, but it’s not quite there yet. In his opinion, cultivators in the Philippines are excellent at producing gold pearls, as their waters and their oysters are better suited for these products. Indonesia will continue to produce all colors, and Australian pearl farmers will concentrate on white, while those in Tahiti focus on the different shades and nuances of black pearls. Source: GIA @topic:15


Title: Natural Conch “Rosebud” Pearls Abstract: Figure 1. “Rosebud” conch pearls of various pink tones ranging from 0.93 to 14.72 ct. Photo by Sood Oil (Judy) Chia.

Non-nacreous conch pearls from Strombus gigas are known mainly for their very attractive pink color and distinctive shimmering appeal due to the characteristic flame structures on their surfaces. Although conch pearls are found in various tones of yellow, brown, and white, the most desirable hue is undoubtedly pink with an intense saturation. The flame structures are due to “crosswise arrays of bundles of aragonite laths or fibers that may reflect or absorb the light that falls on the structure, letting it appear bright or dull” (H.A. Hänni, “Explaining the flame structure of non-nacreous pearls,” The Australian Gemmologist, Vol. 24, No. 4, 2010, pp. 85–88).

In late 2016, GIA’s New York lab staff had the opportunity to study part of Susan Hendrickson’s conch pearl collection. Among the assortment of conch pearls of various sizes, colors, and shapes, a few “rosebud” specimens caught our attention (figure 1). The term “rosebud” is most commonly used to describe characteristically shaped freshwater nacreous pearls, but this is the first time GIA has examined conch pearls with such shapes (figure 2). The nine pink specimens had roundish outlines with a button-like appearance. But in keeping with the rosebud pearl form, they exhibited differences in the bumps or ridges on their surfaces. Some bumps were rounded and spread out, while others were jagged and tightly grouped. The authors could not locate any reports of rosebud conch pearls in the literature, and the cause of these distinctive surface structures is unknown. One possible explanation is that when a pearl forms in a pearl sac positioned in a region of muscular activity rather than the mantle, it will not form in a smooth symmetrical shape (E. Fritsch and E.B. Misiorowski, “The history and gemology of Queen conch ‘pearls’,” Winter 1987 G&G, pp. 208–221).

Figure 2. A shape comparison of a 4.90 ct American freshwater pearl exhibiting
rosebud form (A) and three conch pearls, weighing 1.30, 0.66, and 0.91 ct (B–D).
Photos by Tino Hammid (A) and Joyce WingYan Ho (B–D).
All nine samples displayed typical flame structures under magnification (figure 3). Some of them did not exhibit the flames on the bumpy surface, but only within the smoother areas. Microradiography revealed a tight internal structure with uneven outlines corresponding to the bumpy surfaces. The Raman spectra were characteristic of aragonite and clearly showed additional natural polyenic pigment peaks, both as expected for pearls formed in Strombus gigas mollusks.

Figure 3. This 6.21 ct rosebud conch pearl shows characteristic flame structure at the surface. Photos by Joyce WingYan Ho; fields of view 10.79 mm and 1.26 mm (inset).
There are records of attempts to cultivate conch pearls (H. Acosta-Salmón and M. Davis, “Inducing relaxation in the queen conch Strombus gigas (L.) for cultured pearl production,” Aquaculture, Vol. 262, No. 1, 2007, pp. 73–77; N. Sturman et al., “Cultured Queen conch pearls—A comparison to natural Queen conch pearls,” 32nd International Gemmological Conference, Interlaken, Switzerland, 2011; Summer 2015 GNI, pp. 201–202). No further news about the commercial production of cultured conch pearls has reached the market, however. As a result, conch pearls are still highly desirable and valued by the trade and specialty collectors. The opportunity to study such unique and exciting examples of rosebud conch pearls allowed GIA to expand its understanding of rosebud conch pearls for future reference. Source: GIA @topic:5


Title: Filled Pearl with Surface Features Abstract: Figure 1. This 20.60 ct specimen was purchased by the client as a “natural white pearl.” Photo by Lai Tai-An Gem Lab.

Pearl cultivation has been carried out for more than a century, with newer techniques supplying the trade with larger and more consistently round freshwater and saltwater pearls. While natural pearls are seldom perfectly round, their rarity makes them desirable nevertheless. The Lai Tai-An Gem Lab recently had the chance to examine a specimen that was purchased by the client as a “natural white pearl” (figure 1) while traveling in the Philippines.

The white baroque pearl measured 20.0 × 19.0 × 13.3 mm and weighed 20.60 ct, with a specific gravity of 2.60. It exhibited pink overtone. Long-wave UV produced a strong chalky blue reaction. Magnification revealed the typical overlapping platelet structure expected for nacreous pearls, but two abnormal surface features were also observed. These two areas displayed a coarse appearance and lower luster that differed from the rest of the pearl (figure 2).

Figure 2. Two fillings displayed a coarse appearance and lower luster that differed from the rest of the pearl. Photomicrographs by Lai Tai-An Gem Lab; fields of view 11.5 mm (left) and 8.6 mm (right).

Figure 3. The two filled portions of the pearl, shown in visible light (left images) and the DiamondView (right images). The DiamondView reaction showed a noticeable difference between the nacreous areas and the filled portions of the pearl.
We further analyzed the abnormal surface features to gather more data for future reference. DiamondView imaging showed a noticeable difference between the nacreous areas and the filled portions (figure 3). Raman analysis of the surface features revealed epoxy peaks at 635, 1108, and 1604 cm–1 and aragonite peaks at 1084 and 701 cm–1 (figure 4). These were consistent with results from FTIR reflectance spectrometry that showed calcium carbonate in the form of aragonite, with peaks at approximately 878 and 1484 cm–1.

Figure 4. Raman analysis of the pearl revealed epoxy peaks at 635, 1108, and 1604 cm–1 and aragonite peaks at 701 and 1084 cm–1.

Figure 5. X-radiography proved this was a bead-cultured pearl. The filling was very shallow due to the presence of mother-of-pearl (not visible). Image by Lai Tai-An Gem Lab.
X-radiography (figure 5) proved this was a bead-cultured pearl with a pre-drilled nucleus typically used in freshwater pearl cultivation. The filling was very shallow due to the presence of mother-of-pearl (not visible). Energy-dispersive X-ray fluorescence (EDXRF) analysis detected higher levels of manganese, confirming the pearl’s freshwater origin. The result came as a surprise to the client, who was expecting confirmation of a natural pearl. Such coatings and fillings, which we have seen before, show the importance of obtaining a reliable laboratory report when purchasing such a large pearl. Source: GIA @topic:5


Title: Natural Freshwater “Fish” Pearl Abstract: Figure 1. A 2.12 ct natural freshwater pearl with the form of a fish. Photo by Sood Oil (Judy) Chia.

The increased availability of freshwater cultured pearls in the market has brought their natural counterparts to the attention of collectors and the trade. Most natural freshwater pearls have been obtained from European waters and in the United States from rivers in the Mississippi Valley. A natural pearl occurs without human intervention and takes on the characteristic color and surface properties of the mollusk in which it forms. Freshwater pearls, whether cultured or natural, are attractive due to a wide variety of distinctive shapes, hues, and overtones. The New York lab recently examined a unique fish-shaped brownish orange pearl measuring 21.34 × 6.28 × 2.81 mm and weighing 2.12 ct (figure 1).

The entire nacreous surface was composed of overlapping platelets. We observed no indications of work, such as polishing, that is sometimes performed to improve a pearl’s appearance. One end was wider and more rounded, which bore an uncanny likeness to a fish’s head, with an “eye” and “mouth” also discernible. The lustrous orient along the body narrowed to a rounded point, resembling iridescent fish scales on a tail. Natural pearls are often baroque, and American freshwater pearls in particular are often found as elongated “wing” pearls (J.L. Sweaney and J.R. Latendresse, “Freshwater pearls of North America,” Fall 1984 G&G, pp. 125–140). Energy-dispersive X-ray fluorescence (EDXRF) chemical analysis and observation of X-ray fluorescence showed higher levels of manganese, proving that the pearl formed in a freshwater mussel. No indications of treatment such as dyeing or coating were detected under magnification or using advanced analytical procedures. Real-time microradiography and X-ray computed microtomography (µ-CT) analysis revealed clear natural growth structures that conformed to the pearl’s shape. 3D rendering of the µ-CT data (figure 2) showed a remarkable likeness to a small fish swimming.

Figure 2. 3D software rendering of X-ray µ-CT data revealed the pearl’s uncanny likeness to a fish. Images by Emiko Yazawa.
Although this is not the first pearl GIA has examined that bears a resemblance to a living creature (see Fall 2015 Lab Notes, pp. 319–320), it is nonetheless an extraordinary and rare formation that mirrors the form of a fish in surprising detail. Source: GIA @topic:5


Title: Pearl Species and Localities Abstract: All GIA pearl reports include details about the mollusk (if determinable). The chart below and the downloadable PDF include more information about pearl species, localities, and growth, along with definitions for the 7 Pearl Value Factors™ and terminology GIA uses to describe your pearl.

	This information was included with Pearl Identification Reports and Pearl Classification Reports until March 2013. Source: GIA @topic:5


Title: Pearl Newsletter: Margaritologia Abstract: Margaritologia, a quarterly newsletter on pearls, was recently launched by Elisabeth Strack.

              The Greek word for pearl, margaritēs, was used by Theophrastus in the fourth century BC in the first known effort to explain the scientific origin of the beloved organic gem. Margaritologia, or “the science of pearls,” is a newsletter recently launched by Elisabeth Strack, founder and director of Gemmologisches Institut Hamburg and author of the comprehensive book Pearls. Ms. Strack is also a member of G&G’s editorial review board.

The newsletter, published four times a year in English and German, in print and electronic versions, offers a forum for pearl research findings and news. Topics range from science and history to pearl grading and testing, farming, and market conditions. The first issue, published in October, featured articles on Vietnamese cultured pearls, DNA fingerprinting of pearls, the International Gemmological Conference in Hanoi, Spondylus pearls, a Mikimoto necklace, and a museum exhibition in Mecklenburg, Germany.

A yearly subscription to Margaritologia is €70, with a discounted rate for CPAA or NAJA members. More information can be found at www.gemmologisches-institut-hamburg.de. Source: GIA @topic:5


Title: Majorica Imitation Pearls Abstract: Pearls are one of the most popular gem materials, but only in the past few decades has technology advanced to the point that good-quality imitations could be made. The Majorica S.A. product is remarkably similar in appearance to saltwater cultured pearls. These imitations, often set in high-karat gold in contemporary styles, are sold throughout the world. This article discusses the history of the Majorica imitation pearl, the manufacturing and marketing processes, and the separation of the Majorica product from its cultured counterparts. Source: GIA @topic:15


Title: Pearl Fashion Through the Ages Abstract: This article traces the use of pearls from antiquity to the initial appearance of cultured pearls in the 1920s. The first section touches on the early fascination with pearls as revealed through historical literature, including Cleopatra's pearls, Roman pearl jewelry, and medicinal pearl recipes of the Middle Ages. During the Renaissance, Spain's exploration of the New World resulted in the discovery of vast quantities of valuable pearls that were eventually spread throughout Europe. Queen Elizabeth I's magnificent collection of pearls and the intriguing baroque pearl figurines of the later Renaissance are also discussed. The article concludes with a review of pearl fashion from 1800 to 1930, including delicate Victorian seed-pearl jewelry, Queen Alexandra's dog-collar chokers, and Art Deco pearl-inlaid jewelry. Source: GIA @topic:6


Title: Freshwater Pearls of North America Abstract: Natural pearls are among the rarest and most valued of fine gems. American freshwater pearls have a history thousands of years old and played a particularly prominent role in the jewelry of the late 19th and early 20th centuries. Today, though a fraction of its original size, the American freshwater pearl industry continues to produce fine material for the jeweler worldwide. The source of this pearl is the Unio mussel, "fished" by brailing boats and intrepid divers from the rivers and lakes of America. From the Unio in which it grows, the American freshwater pearl derives its distinctive shapes and colors. A new entry to the American pearl industry is the freshwater cultured pearl, illustrated in this article for the first time ever. Source: GIA @topic:5


Title: How Do I Know if the Fancy Melee in My Jewelry is Natural Diamond? Abstract: Melee diamonds are like the bridesmaids to the bride, the chorus line to a Broadway show or a side dish to a holiday meal. They are there to draw attention to the star of the show, adding intrigue and interest — but never detracting from the main event.

Melee diamonds, which weigh less than 0.2 carats, are inexpensive compared to larger stones, so they can be generously used as dazzling accents in jewelry and watches. Their brightness and scintillation enhance the center stone in a halo-style ring or create intricate patterns in a pave-set design. Often cut as round shapes, they are also available in fancy shapes, such as emerald, princess, radiant and marquise.

The challenge for the jewelry trade: it is quicker and cheaper to grow small diamond crystals, so melee-size laboratory-grown and simulated diamonds are abundant in the market. Given their small size and the large number of loose stones in a parcel, laboratory-grown and treated or simulant melee diamonds can be mixed in with natural diamonds — and missed.

GIA addressed this challenge in 2016 with a melee analysis service for round diamonds, the most common shape of melee, an automated system that analyzes and sorts melee-sized diamonds quickly and accurately. The goal of the automated process is to minimize the percentage of natural diamonds that will be referred for further testing.

“The best instrument will pass 100 percent of natural diamonds, with 100 percent laboratory-grown and simulants referred for further testing,” said Tom Moses, executive vice president and chief laboratory and research officer. “No single instrument in the world, however, can pass 100 percent of natural diamonds, because there is always a small percentage of natural diamonds that show similar features to man-made or treated stones.”

Fancy melee diamond screening device. Photo: Mitchell Lyn
Millions and millions of small round diamonds have been analyzed since then, but there has also been a need to screen fancy-shaped melee, according to Moses.

“The watch industry, for example, uses many fancy shaped diamonds and wants to use high-quality natural melee diamonds. They often depend on the suppliers to guarantee that their fancy shape melee is natural and not man-made,” Moses said. To meet the needs of their customers, many diamond suppliers want to get their fancy shape melee screened by GIA.

GIA scientists working on the issue of fancy shape melee screening developed a set of operating principles and laser technology they believe address this complex task. The team of scientists, along with engineers from GIA’s instruments group, worked together to create a prototype. After testing, software and mechanical engineers helped to develop a fully automatic system for large-scale screening of fancy shape melee diamonds.

The process to develop the technology and build the new system took about three years, but the team is pleased with the results, Moses said. Compared with the previous instrument for diamond melee, this new one refers fewer natural diamonds for further testing.

“With this new instrument, we can analyze every shape of melee,” Moses said. “The new machine uses new principles and analysis techniques to detect laboratory-grown and simulant melee from natural diamonds — and can do it much more efficiently and accurately than ever before.”

Metrology Technician Nicole Phelan operates a fancy melee diamond screening device. Photo: Mitchell Lyn
The new GIA Analysis Service for fancy shapes was announced in August 2020 and is offered at most GIA labs. Click here for more details.
Benefits For Suppliers and Retailers
The ability to sort natural melee from man-made, treated or simulated stones, has the potential to offer new opportunities for suppliers.
“We will discuss this with our niche and elite customers. Only they would prefer something like this as it will be a value addition to their product,” said Premal Chokshi, general manager of sales for Rosy Blue in Mumbai. “Regular diamond manufacturers, traders and diamond jewelers will not pay for getting their [melee] stones certified; it’s only the niche customers we want to target.”

Melee screening also gives retailers the ability to assure their clients that all of the melee in any piece of jewelry or watch is 100 percent natural diamond.

“For the clients, they will be able to give consumers the confidence that the goods coming to them have already been screened and tested by the biggest lab in the world — GIA,” said Rajesh Lakhani, director of Kiran Gems in Mumbai. “The trust and faith relationship is 100 percent there and people are attracted to that — especially consumers.” Source: GIA @topic:4


Title: Survey of Colored Stone Preferences Among Younger Generations Abstract: Figure 1. Survey participants identified their top consideration when purchasing colored stones or colored stone jewelry.
The global colored stone market is dynamic and constantly evolving. To understand general perceptions and preferences regarding colored stones among designers and potential end consumers from the younger generations, the author conducted a survey in April 2023. The survey targeted 300 respondents under the age of 35, all followers of Donna Jewel (@donna.jewel), an Instagram community designed to champion jewelry from artisans and emerging talents worldwide. Although not scientific, the results of the survey are nonetheless revealing.
Demographics and background: The survey participants consisted of 50% Millennials (born between 1981 and 1996) and 50% from Generation Z (born from 1997 onward). All respondents were over the age of 18. Forty percent were from the United States and another 40% from Europe (specifically Italy, France, the United Kingdom, and Germany), with the remainder split between Latin America (mainly Brazil) and Asia (mainly India and Iran). Respondents identified themselves as gem and jewelry lovers (50%), designers (33%), or gem and jewelry experts (17%).
Colored stone preferences: Participants were asked to choose their single most important consideration when buying colored stones or colored stone jewelry: aesthetics, preciousness, naturalness, sustainability and ethics, symbolism, or economic value. As shown in figure 1, the top two responses were aesthetics (35%) and preciousness (30%). Naturalness was also an important consideration (receiving 20%), while sustainability and ethics was chosen by 10% of the interviewees, symbolism by 4%, and economic value by only 1%.

Figure 2. The preferences of survey respondents regarding natural vs. synthetic (lab-grown) gemstones and untreated vs. treated gemstones.
Given the choice between natural or synthetic gemstones (figure 2, left), 70% chose natural. Only 10% selected synthetic, while an additional 15% expressed no preference. When asked to explain their preferences, the participants who chose natural stones perceived them as unique, rare, and authentic products of nature, capable of evoking emotion, unlike their synthetic counterparts. Those who chose synthetic gemstones viewed them as more sustainable, ethical, and affordable. The topic of natural and synthetic gemstones remains extremely relevant.
Regarding treated vs. untreated natural gemstones (figure 2, right), 75% preferred untreated, which they perceive as more beautiful for their uniqueness and originality. They viewed natural imperfections as an added value lost during treatment. Only 15% preferred treated stones, while 10% acknowledged that they were not informed on the topic.
When asked whether they preferred “precious” or “semi-precious” stones, the participants proved generally indifferent (designers and potential end consumers alike). They associate preciousness with a broader definition more related to uniqueness, emotion, and originality.
Designer perspectives: Designers participating in this survey revealed that they follow both trends and personal inspiration. They noted several uncommon gemstones of particular interest: rainbow obsidian, red beryl, sphene, pargasite, chrysoberyl, scapolite, axinite, enstatite, and benitoite. Fifty percent indicated that they had purchased or used for their jewelry artificially manufactured materials such as glass or cubic zirconia.
At the end of the survey, participants were asked what topics they would be most interested in learning more about. They expressed a strong desire for more knowledge on uncommon and unique gemstones, original colors, treatments, history, lore, origin, and sustainability.
The survey highlighted the younger generations’ strong interest in what is unique, original, authentic, and emotional rather than alignment with traditional notions of beauty and preciousness. Naturalness emerged as an important element for the interviewees, who appreciated imperfection as a mark of authenticity and originality. Young designers favored uncommon and original gemstones with distinct and extravagant colors (especially yellows, blues, greens, and reds). While designers sought uniqueness, rarity, and extravagance, potential end customers were also looking for a gemstone with a story to tell. Source: GIA @topic:10


Title: A New Type of Composite Turquoise Abstract: Several conspicuously colored specimens marketed as dyed and/or stabilized turquoise were recently examined. They were purple to purple-pink, yellow-green, and blue, in veined and unveined varieties. Testing revealed that all the specimens were composites of turquoise pieces bonded together; the purple to purple-pink and yellow-green samples were bonded with a colored polymer, and the blue ones had a colorless polymer. This article presents the gemological properties and EDXRF and FTIR analyses of this material, along with its reaction to the solvents acetone and methylene chloride. Source: GIA @topic:13


Title: The Rubies of Burma: A Review of the Mogok Stone Tract Abstract: For centuries, the Mogok Stone Tract of Burma has provided the world with its finest rubies. The mining district is situated about 700 km north of the capital city of Rangoon, with the rubies found principally in alluvial deposits weathering out of a crystalline limestone or marble. This article reviews the history of this famous locality, the geology of the area, and the mining methods that have predominated. Also covered is the gemology of these stones, including those inclusions that are characteristic of Burmese origin, and a discussion of famous rubies from Mogok. Source: GIA @topic:1


Title: Turquoise from Zhushan County, Hubei Province, China Abstract: A relatively new source of gem-quality turquoise is hosted within slates in Zhushan County of China’s Hubei Province. Rough and polished samples were studied using standard gemological methods, as well as FTIR and UV-Vis-NIR spectroscopy. The turquoise formed nodular, massive, and veinlet assemblages. Brown and black veinlets/patches and irregular white blebs were common, and microscopic observation also revealed microcrystalline and spherulitic structures. In general, the nodular specimens were of the highest quality. The deposits show considerable potential as a commercial source of gem-quality turquoise. Source: GIA @topic:13


Title: Exceptional Freeform Tanzanite and Oregon Sunstone Rings Abstract: Figure 1. This ring is set with a spectacular 27.20 ct vivid blue freeform tanzanite. Photo courtesy of Sonja Kreis Unique Jewelry.

At the Gem and Jewelry Exchange (GJX), we caught up with gem artist Alexander Kreis (Sonja Kreis Unique Jewelry, Niederworresbach, Germany). As we’ve noted in previous Tucson reports, theirs is a family business: father Stefan buying the rough, mother Sonja designing the jewelry, and Alexander cutting the gems. Alexander and Sonja showed us a new ring (figure 1) set with a spectacular 27.20 ct vivid blue freeform tanzanite (figure 2). He explained that he had recently traveled to East Africa seeking a singular piece of gem rough to inspire an exceptional jewelry piece. He found his inspiration in Tanzania with a 65 ct rough tanzanite of remarkable color and clarity.

Figure 2. The gem was cut from a 13 g rough tanzanite of remarkable color and clarity.
Photo courtesy of Sonja Kreis Unique Jewelry.
Even with such a top-quality piece, Alexander cautioned that success is never guaranteed. Unlike baseball—where you get three chances—with cutting, it’s “one strike and you’re out!” He added that the gem can never be its best if the cutter misjudges and makes it too flat. For this one-of-a-kind rough, classic cutting styles such as oval or cushion shapes might be counterproductive if too much weight is lost getting proportions right or if the deep blue color is lost.

For Alexander, cutting is an “intuitive adventure” in which it might take months to place the first facet. The finished stone is a nonsymmetrical shield shape with a mixture of large and small facets that catch the light and create a strong sense of movement. According to him, cutting a freeform allows more reflections so that the gem will exhibit maximum sparkle and display the best possible color from the rough.

	Alexander & Sonja Kreis - Kreis Jewellery

In this video, master cutter Alexander Kreis and his mother Sonja, the firm’s goldsmith, explain the design of the extraordinary 27.20 ct tanzanite and the ring specially fabricated to complement it.
The facet dimensions govern the size of the reflections from the gem’s surface, and a series of grooves on the base of the gem running at right angles to the facets on the top create sharp angles, heightening the sense of movement and drama (figure 3). For Alexander, this represents not just the movement of the earth, but also the volume of material the workers had to shift to recover the gems.

Figure 3. Angled grooves on the base of the 27.20 ct freeform tanzanite create a dramatic sense of movement. Photo courtesy of Sonja Kreis Unique Jewelry.
He reminded us that mining in Merelani is a challenge, taking place at depths of up to 3,900 ft (1,189 meters). Miners can only work for short periods due to temperatures reaching 122°F (50°C), and they must take regular breaks in designated cooling areas.

As a goldsmith and jewelry designer, Sonja follows a 500-year family tradition. She explained that it’s not just attributes like size, shape, and color that drive the design of a jewelry piece to complement the stone. She normally starts thinking about the jewelry design when Alexander completes the stone, noting that it can change substantially from the rough crystal to the finished piece.

When Sonja saw the finished cut tanzanite, still wet from the wheel, she held it and examined it from every angle in front of a mirror to get a feeling for the gem and for the best type of jewelry mounting to accompany it. It’s not just the size and shape that influences the gem, she noted, but the story behind it, too. This aspect is increasingly important for clients who like to buy into the romance and unique attributes of a jewelry piece. In this case, the rose gold on the mounting represents the heat the miners endure to recover the gems at depth in the mine, while the white gold cradling the tanzanite stands for the designated cooling areas where the workers have a chance to recover. The diamonds along the edges of the center gem symbolize the many stones that have been moved out of the way to reach the tanzanite. The branching metalwork in the galleries at each end of the mounting represents the air that must be pressed into the mine depths to sustain the miners. The little trail of melee diamonds around the curve of the ring’s shank adds a final touch of elegance to a significant piece with a large center stone.

Sonja also shared with us a striking ring centered on a 28.21 ct freeform Oregon sunstone from the Dust Devil mine (figure 4). The organic outline of the mounting complements the smooth contours of the gem, which rests in an 18K rose gold “cup.” The cup is highly polished to reflect light back through the gem and amplify its rich orange color. The gem itself is shot through with an array of glittering copper particles that catch the light and add to the piece’s allure.

Figure 4. A 28.21 ct freeform Oregon sunstone from the Dust Devil mine is the centerpiece of this ring. Photo courtesy of Sonja Kreis Unique Jewelry. Source: GIA @topic:1


Title: Gray Spinel: A New Trend in Colored Stones Abstract: Figure 1. Spinel with nearly perfectly neutral gray color with only a slightly bluish tinge, 24.15 ct. Photo by Robert Weldon/GIA, courtesy of 3090 Gems, LLC.

In recent years, the colored stone world has seen a growing appetite for unusual colors. Ruby, sapphire, and emerald with strong saturation but not overly dark tones have always been the mainstay of the colored stone market. But now there is stronger demand for stones in nontraditional colors that might have been difficult to move a decade or two ago. Especially notable is the growing popularity of lighter-toned, lower-saturation pastel stones such as garnets from East Africa or Montana sapphires.
Gray spinels were one of the obvious new trends at the Tucson shows this year. It was not hard to find exhibitors showing off their gray spinel, and everyone who had them commented on how quickly they were selling. The story is remarkable in that the colored stone market has accepted a gemstone that by definition has an unsaturated color—a gray color, no less. Most gray spinel has a minor blue or violet secondary color component. It is relatively rare to find a spinel with a perfectly neutral gray color. These stones have the most value, which increases as the depth of the gray increases. Most of the specimens on display in Tucson were under a carat. Stones larger than a few carats were relatively rare, but we were able to document some with exceptional color, such as the 24.15 ct bluish gray spinel cut by 3090 Gems, LLC in figure 1 or the slightly bluish gray matched pair (10.34 carats total) from Nomad’s in figure 2.

Figure 2. Matched pair of slightly bluish gray spinels with a combined weight of 10.34 carats. Photo by Robert Weldon/GIA, courtesy of Nomad’s.
Gray spinel’s success is due in large part to strong marketing. Of particular note is the influence of social media in bringing this material to the market. In the last year or so, these spinels became quite popular in gemstone circles on Facebook and Instagram. In our interview with cutter Jeff Hapeman, he noted how social media has fundamentally altered the industry by allowing gem dealers to satisfy more eclectic desires and by giving consumers power to find and purchase novel and unusual stones that were traditionally unavailable. As we continue to witness the disruptive power of social media in the industry, gray spinel will not be the last story we hear of a once unmarketable color being embraced by the colored stone world. Source: GIA @topic:1


Title: Ginger Garnet, “Fancy” Tanzanite Abstract: Figure 1. Marketed as “ginger” garnet, these four garnets range from 8.33 to 35.54 ct. Photo by Robert Weldon/GIA; courtesy of Advanced Quality.

Kobi Sevdermish (Advanced Quality, Ramat Gan, Israel) showed us large fine “ginger” garnets and discussed the cutting of natural-color tanzanite crystals. The garnets are from a new find in Tanzania, discovered in late 2014. In large sizes, the stones have a pleasing “open” pinkish orange or orangy red hue (figure 1). By “open,” Sevdermish meant the tone is not too dark, remaining lively and relatively bright even in sizes above 30 ct. He noted that many red garnets cut in large sizes have a tendency to become very dark, and this material avoids that pitfall. If fashioned correctly, it “pops.” Along with the virtues of lighter tones and relatively large sizes, it possesses high clarity.

	Advanced Quality, Ltd. | “Ginger” garnets from Tanzania, more on “fancy” tanzanite

Kobi Sevdermish of Advanced Quality introduces us to new pinkish orange to orangy red “ginger” garnets that remain bright in larger sizes. He also outlines the trials and tribulations of sourcing and cutting the unique “fancy” tanzanite crystals his company specializes in.
Supply has been limited—Sevdermish had only seen a few parcels of larger rough suitable for cutting gems up to 40 ct—and some of this material was of lower clarity. Standard gemological testing revealed an RI of 1.74 and an SG in the range of “Malaya” garnet (3.78–3.85).

As in 2014, Sevdermish reported that “natural-color” tanzanite remained a very successful item for Advanced Quality. He showed us a selection of unheated gems in a range of subtle secondary colors (greens and pinks) behind the predominant “typical” blue to purple tanzanite colors (figure 2). Sales have been strong in Europe and particularly Asia. According to Sevdermish, this is because no two are exactly alike. To demonstrate, he showed us a large suite of mixed fancy colors (figure 3).

Figure 2. A selection of reportedly natural-color, unheated tanzanites ranging from 9.93 to 27.86 ct. Photo by Duncan Pay/GIA; courtesy of Advanced Quality.

Figure 3. Kobi Sevdermish of Advanced Color shows off natural-color tanzanite, including a remarkable multicolor necklace of almost 170 carats total. Photo by Duncan Pay/GIA.
He explained that rough of “odd” colors—unheated pinks and greens—did turn up over the years, but in the last year and a half, material from Block B of the tanzanite mining area has provided some “magnificent” natural colors: lavender, cognac or golden colors, and very rare pink and yellow and green.

Sevdermish noted that buying suitable tanzanite rough in these colors is a painstaking business, even though the company has cultivated connections in Africa that locate this material for them. Some purchases take time, he said, and require him to extend buying trips to obtain a few special, unique pieces. He added that it takes persistence to negotiate with miners and their representatives. And if no other buyers outbid you, you succeed. Sevdermish said that many of the stones at his booth were cut about a week and a half earlier.

Advanced Quality documents, through video recording and photography, each rough piece as it goes through the planning, sawing, and faceting process—in essence, the mine-to-market story of each significant gem. In this way, Sevdermish asserted the company can show—to the best of its knowledge—the unheated nature of its gems to clients. Many of the stones promoted as “unheated” in the market are actually the products of less-than-successful heating, he explained.

Just a couple of weeks earlier, he managed to obtain a few large pieces of rough with unique light yellow colors, one of which yielded a 27.59 ct antique cut (figure 4). The gem came out predominantly greenish yellow, but with flashes of lilac pink, which is what Sevdermish initially expected from the rough. The company debated whether to cut the original rough, as it was such a spectacular piece, but ultimately decided to fashion it because the crystal was not quite perfect enough to be a specimen.

Figure 4. This 27.59 ct unheated, natural-color zoisite or “fancy” tanzanite shows a subtle tint of lilac pink against a greenish yellow bodycolor. Photo by Robert Weldon/GIA; courtesy of Advanced Quality.
Sevdermish described buying and cutting rough as a lottery. Certain gems—some spinels or even regular tanzanite—are more or less predictable. But with others, especially the rough for this “fancy-color” tanzanite, the results are less foreseeable. The rough for the 27.59 ct gem promised a “kaleidoscope of colors” blending pink, yellow, and green, so Sevdermish expected to see an interplay of colors inside the fashioned gem. Instead, he was dismayed to find the gem was colorless. Fortunately, Sevdermish reported, the hoped-for greenish yellow color returned after the gem had “rested” for two days in its parcel paper. Source: GIA @topic:1


Title: Mine to Market: The ‘Adventure Story’ of Colored Stones Abstract: Andy Lucas, GIA’s education manager of field gemology, and Dr. Tao Hsu, GIA’s technical editor and research specialist for Gems & Gemology, presented pieces of their field research on the colored gemstone supply chain at the Institute’s Carlsbad campus on Jan. 13. “Colored stones are the last real adventure luxury product,” Lucas said. “What other luxury product really has an adventure story to it?” Video image capture by Albert Salvato and Larry Lavitt

	When it comes to selling colored stones, a retailer’s supply-chain knowledge has tangible benefits at the counter – or wherever the point of sale happens to be.

	That’s what Andy Lucas, GIA’s education manager of field gemology, and Dr. Tao Hsu, technical editor and research specialist for Gems & Gemology, told local GIA alumni and Women’s Jewelry Association members at GIA's Carlsbad campus on Jan. 13. Lucas and Hsu have traveled the world together to discover and document what happens as a gemstone travels from the mine to the market.

	The allure of colored stones has not changed much over the centuries, Lucas said, so retailers need to share the romance and adventure.

	“The people who are more knowledgeable about the story are better at making customers feel comfortable, at gaining their trust and at piquing their interest,” he said.

	Lucas acknowledged that the details of that story have evolved over the years.

	“People today have more access to information … they’re more interested in mining, about the art of cutting,” he said. “There are also a lot of ethical issues that come into play, and people are interested in hearing about them.”

	One of the first things that they noticed on their expeditions is that the technology at a colored gem’s source ranges from the large-scale mines operated by capital-rich companies, to the smaller artisanal mines. Both types of operations can both “complement and conflict with each other.”

	Hsu cited the Kagem Mine, a primary emerald mine in Zambia, as one of the best examples of modern mechanized, large-scale mining she's seen.

	“I was amazed at the size of the pit,” she said. “Their primary production is from this pit that’s over a kilometer long. The explosion that’s involved, because this is hard-rock mining, is quite amazing to see − and to feel the shake of the ground.” Hsu said that Gemfields, which owns the mine, adheres to a strict, consistent grading system for its emeralds.

		“People today have more access to information … they’re more interested in mining, about the art of cutting. There are also a lot of ethical issues that come into play, and people are interested in hearing about them.”

		Andy Lucas, education manager of field gemology, GIA

	Lucas shared examples of artisanal and small-scale mining, which some experts believe are responsible for 70 percent of colored stone production. Even within this category, situations are diverse.

	He said operations in Africa “vary tremendously.” Some of the artisanal mines have “illegal mining, environmental destruction, and conflict with larger organized mining.”

	“In Sri Lanka, it’s structured and legalized – there are partnerships with the mine owners, the people who put up the capital, the land owners, and the miners.” In Mozambique’s ruby mines, however, unlicensed miners called garimpeiros often mine on Gemfields’ property, which can be a problem since they don’t “have an investment in restoring the environment” as Gemfields does.

	In Pailin, Cambodia, there is “more of a problematic situation,” with concerns such as bribery, disease and an overall lack of legal, formalized structure to the mining system.

	“Artisanal mining is not one type of a situation around the world – it’s not always positive, it’s not always negative,” Lucas said. “One way forward is for the industry to provide opportunities for all artisanal miners to come into the formal system and be protected. This could help protect the environment and the rights of larger mining companies and their investors, as well as create a transparent supply chain.”

	Lucas noted that one technological development is changing artisanal mining: the smart phone. “You have someone in the middle of nowhere, they take a picture and they email it to Bangkok for a quote,” he said. “The smart phone is revolutionizing the independent miner with connections all over the world.”

	Another factor in the supply chain is that countries like Sri Lanka to Colombia cut gemstones at their source. In Colombia, for example, almost all emeralds are cut in-country. “They have become the experts in cutting Colombian emeralds,” he said.

	Lucas said this is part of an overall trend. “The divisions that used to exist in jewelry mining, cutting and manufacturing are blurry. A lot more vertical integration and consolidation is going on,” he said.

	The CEO of RMC Gems, for example, told Lucas that five or 10 years ago, he had a large number of small companies – other wholesalers, jewelry manufacturers and retailers − as clients. Most of those companies are gone or have consolidated, so now the companies he works most with are jewelry television programs, large jewelry manufacturers and retail chains.

	“The small people are less and less able to compete and add value,” Lucas said. “The larger, vertically integrated, better-funded companies are taking over in the business.”

Dr. Tao Hsu explained that upon beginning her field research with GIA, she was struck by the stories of the diverse individuals and families around the world who make up the colored stone industry. Video image capture by Albert Salvato and Larry Lavitt

	Hsu said you have to talk about China when you are talking about manufacturing, because “they manufacture everything for the rest of the world – including colored stones.”

	She said one of the most striking aspects of a trip they took to China’s Guangdong province was that, regardless of the size of the facility, “everywhere you visited, you saw the focus and efficiency of the cutters.” In that particular area, where huge manufacturing facilities are clustered, companies are even promoting “China Cut” as a brand.

	Lucas visited Jaipur, where he found “all types of sophistication levels,” calling it “an amazing place to see modernization and tradition side-by-side, hand-in-hand.”

	He also learned more about a retail player that’s changing the landscape for colored stone manufacturers: jewelry television.

	“The biggest growing market is jewelry television,” Lucas said, noting a colored stone manufacturer they interviewed there who loves that jewelry television goes from the high- to low-end and that they buy in “huge” volume.

	One vertically integrated jewelry television entrepreneur told the GIA team his company’s team of 3,000 produces one million pieces of jewelry a month − by creating engaging programs that show the customer where the stones come from and how they are made into jewelry: the romance and adventure story.

	“Their customer wants to be entertained. They come home and turn on the television – they’ll go to the mines, they’ll see the cutting,” Lucas said. They become engaged with the story of the stone and call in and make a purchase.

	“I think you’re going to see an expansion of this,” Lucas said.

	Hsu said the Chinese market, which the duo visited and wrote about in 2014, “is now the second largest market for jewelry and luxury goods.” The Chinese, she said, bought about half of the luxury goods in the world, particularly when shopping overseas as tourists.

	The customers, companies and channels may evolve, but Lucas stressed that the story was still key.

	He told of mine operator Marcelo Ribeiro, who had a unique emerald graded at GIA's New York lab and unsuccessfully tried to sell it to a New York wholesaler. Disappointed, Ribeiro took the stone to a show in Hong Kong. A high-end retail jeweler from Bangkok liked the color of the stone, but wanted to know more about it.

	“Marcelo told him about the Belmont mine, the environmental protection, the sophistication in the operation, the family history, about the workers at the mine, their cutting at the mine,” Lucas said. “This guy was sold, he had a customer for it … and the mine-to-market story is what sold that stone.” Source: GIA @topic:10


Title: Status of Ruby and Sapphire Mining in the Mogok Stone Tract Abstract: Burma, now named Myanmar, has for centuries been considered the world's preeminent source of fine rubies. Today, after nearly three decades of limited gem production, there is a resurgence of mining activity at the famous Mogok Stone Tract. New developments include mechanized government mines and joint-venture mining operations with Myanmar nationals. This article, based on two recent visits to Mogok, briefly reviews the mining history and geology of this extraordinary locality, and describes the current status of mining and the methods used to recover rubies and sapphires in the Mogok area. Limited statistics on gem production are also presented, as is a map of the area showing many of the active mine sites. Source: GIA @topic:1


Title: Mogok Expedition Series, Part 3: The Market and the Stones Abstract: At the Barnardmyo weekly morning market, a Lissu trader offers a rough peridot in matrix for sale while a baby observes from her mother’s back. Photo by Andy Lucas, ©GIA.

	The Market and the Stones
We visited several open-air gem markets in the towns of the Mogok Stone Tract. These included the "Yoke Shin Yone" morning market, usually called the "cinema gem market," and the "Pan Shan" afternoon market, both in Mogok. In Kyatpyin, we went to the "Aung Thit Lwin" morning market and the "Pann Ma" afternoon market. All four of these take place daily. We also visited an interesting market held once a week at the village of Barnardmyo, about an hour's drive north of Mogok.

Each market had its own flavor. At the Barnardmyo weekly market, vegetables and livestock were easier to find than gems. Most of the gems traded there were rough stones brought by local farmers or kanase who had spent some time mining around. The Mogok afternoon market at Pan Shan, held from about 1:00 to 3:00 pm, is definitively the larger and more modern one, with its tables and colorful large umbrellas protecting merchants from the sun or the rain. It has two parts, one for rough stones and crystal specimens and another for faceted gems. The morning "cinema" market is very peculiar, as people place all their stones (mainly rough) in front of them on low tables or on the floor. Most of the stones traded there are of low quality, but it is a colorful market that showcases the variety of gems produced in the area. In Kyaptyin, the morning and evening markets are more like a large crowd of people meeting in the street.

While the markets had their own specialties, they shared common threads. When we visited morning and afternoon markets or even the ones in Mogok and Kyatpyin, we often saw the same dealers and kanase women offering us the same stones, though often at much lower prices than before. In Mogok, time runs much slower than in places like New York or Hong Kong, and closing a deal on a stone can take weeks.

The markets were always bustling with activity. The action was primarily among local dealers, traders, and kanase women. Foreigners were always easy for local dealers to spot, and if they were considered serious buyers they were quickly surrounded with offers of gemstones for sale. Foreigners are not legally allowed to purchase gems in Burmese mining areas such as Mogok, but in practice it seems the authorities are tolerant when they only buy a few souvenirs. In any case, the legal export process in Myanmar is complicated, and only faceted stones mounted in jewelry can be exported easily, if purchased from a registered shop.

Both rough and cut gemstones were offered for sale. There were mineral specimens and even finished jewelry at the markets as well. At the Barnardmyo morning gem market, gemstones were a minor attraction while produce and livestock took center stage.

The stones were predominantly lower quality, with most of the better-quality material sold discreetly through dealers to established customers. Often the most stunning features of the gem markets were the kanase women in their hats and colorful attire, selling their wares. To add a modern twist, it was common to see women and men wearing motorcycle helmets while dealing gems. The gem torch was also prevalent among serious traders, along with the occasional head loupe.

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	The Mogok Stone Tract Gem Markets

	The Value Chain
Most of our expedition was spent at gem mines and gem markets, as that was the focus of our trip. However, it is always interesting at any location, and especially at a source, to witness the area’s complete value chain. The first thing we noticed in the markets was that finished stones were offered for sale along with the rough. It is not uncommon for stones to be fashioned at cutting centers far from a gem source and be brought back to that source for sale. However, many of the stones seemed to be cut in the Mogok area.

We visited a small but active cottage-industry cutting center. The word "cottage" is meant literally, as the cutting was done in people’s homes, which is very common in Mogok. The cutting machines were amazing as they were not powered by electricity but by foot power. The cutters pedaled back and forth to power the lapidary wheel and polish the stones. It was truly eco-friendly gem cutting.

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	Mogok’s Cottage Cutting Industry
The cutters were fashioning ruby, intensely colored spinel, sapphire, peridot, and other native Mogok Stone Tract gems. While many of the cut stones in the market had what are called native cuts with less than ideal proportions, some were cut very well and the stones that were fashioned at this tiny home-based factory were well cut and beautiful.

Other components of the local gemstone value chain were gem paintings. The authors had both previously seen this industry in the Luc Yen area of Vietnam. In Mogok, we witnessed a master artist, a gem-painting factory, and some stores selling gem paintings. This art form incorporates tiny gems not suited for jewelry use and turns them into artistic creations. Being able to utilize all the material from a mine in some profitable fashion increases the likelihood of continued mining. Hopefully, this art form will grow and spread throughout gem-mining communities.

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	Mogok’s Gem Painters

	My Final Impressions
Mogok is a magical place and a mecca for gemologists. This author is grateful to co-author Vincent Pardieu for inviting him to come along on this expedition to Mogok. I have always wanted to visit the location that was the stuff of legends, visited by some of the most famous gemologists in the world.

	The joint expedition between GIA Laboratory and GIA Education, led by Vincent Pardieu, proved to be highly successful. Photo by Andy Lucas, ©GIA.
Many images of this land remain in my mind. The kanase women at Baw Lone Gyi against the white marble powder and in the open-air gem markets, the friendliness of the people, the amazing food served by the restaurants and street vendors, the night market. Add to all this the main draw for a gemologist to this land: the white areas on the mountains where gem mining occurred, the incredible black weathered marble rock pinnacles, the amazing crevices in the marble that could reach depths of hundreds of meters, the miners who navigated those depths and did the hard work of bringing up the gem-containing marble. All inspired by the intensely colored gemstones sometimes hiding within nature’s white marble gift wrapping. Source: GIA @topic:7


Title: Fancy Color Diamond Quality Factors Abstract: This 10.12 ct Fancy Vivid yellow pear shape illustrates the effect a fancy shape can have on intensifying the color in a yellow diamond. - Courtesy the Scarselli Family

Color
In diamonds, rarity equals value. With diamonds in the normal range, value is based on the absence of color, because colorless diamonds are the rarest. With fancy color diamonds—the ones outside the normal color range—the rarest and most valuable colors are saturated pinks, blues, and greens. In all cases, even very slight color differences can have a big impact on value.

Compared to fancy yellows and browns, diamonds with a noticeable hint of any other hue are considerably more rare. Even in light tones and weak saturation, as long as they show color in the face-up position, they qualify as fancy colors. Red, green, and blue diamonds with medium to dark tones and moderate saturations are extremely rare.

Grading fancy color diamonds is complex and specialized, and it takes highly trained laboratory graders to complete the process accurately.

The GIA system for color-grading fancy color diamonds is designed to accommodate the fact that not all colored diamonds have the same depth of color. For example, yellow diamonds occur in a wide range of saturations, while blue diamonds do not.

	Fancy color diamonds have a range of color strength with the intense and vivid colored diamonds being the most rare.
Diamonds with red or reddish colors are extremely rare and highly valued. Pure pinks are more popular than diamonds that are purplish, orangy, brownish, or grayish. Trade professionals market some very attractive stones in this category as “rose-colored,” and some stones with purplish tints as “mauve” diamonds.

Blue diamonds are extremely rare. They generally have a slight hint of gray, so they’re rarely as highly saturated as blue sapphires. Their color is caused by the presence of boron impurities—the more boron, the deeper the blue.

	Blue diamonds are exteremely rare and those with strong color are some of the rarest
	gemstones.
Fancy green diamonds are typically light in tone and low in saturation. Their color often appears muted, with a grayish or brownish cast. The hue is generally in the yellowish green category. In most green diamonds, the hue is confined to the surface, and rarely extends through the entire stone. That’s why cutters try to leave as much of the natural rough around the girdle as possible.

Green diamonds get their color when radiation displaces carbon atoms from their normal positions in the crystal structure. This can happen naturally when diamond deposits lie near radioactive rocks, or artificially as a result of treatment by irradiation.

Naturally colored green diamonds are extremely rare. Because of their rarity and the very real possibility of treatment, green diamonds are always regarded with suspicion and examined carefully in gemological laboratories. Even so, advanced gemological testing can’t always determine color origin in green diamonds.

Brown is the most common fancy diamond color and also the earliest to be used in jewelry. Second-century Romans set brown diamonds in rings. In modern times, however, they took some time to become popular.

Brown diamonds were typically considered good only for industrial use until the 1980s, when abundant quantities of them began to appear in the production of the Argyle mines. The Australians fashioned them and set them in jewelry. They gave them names like “cognac” and “champagne.” The marketing worked, and brown diamonds are found in many medium-priced jewelry designs today.

	Diamond graders look for the strongest areas of characteristic color when grading. These are represented by the darker shaded areas in the illustrations for each Fancy color diamond.
Brown diamonds range in tone from very light to very dark. Consumers generally prefer brown diamonds in medium to dark tones with a warm, golden to reddish appearance. They generally show a hint of greenish, yellowish, orangy, or reddish modifying colors.

Yellow is diamond’s second most common fancy color. Yellow diamonds are sometimes marketed as “canary.” While this isn’t a proper grading term, it’s commonly used in the trade to describe fancy yellow diamonds.

Until the late 1990s, there was not much demand for black diamonds. But designers started using them in jewelry, especially contrasted with tiny colorless diamonds in pavé settings, and they began to gain in popularity.

Fancy white diamonds also exist. They have a milky white color. Sometimes white diamonds are cut to display beautiful opalescent flashes of color.

There are also gray diamonds. Most of them contain a high level of hydrogen as an impurity element, which probably causes their color.

Clarity
With fancy color diamonds, color is the dominant value factor. Even diamonds with numerous inclusions that result in a low clarity grade are prized by connoisseurs if they display attractive face-up color. Of course, inclusions that threaten the gem’s durability can lower a fancy color diamond’s value significantly. Fancy color diamonds can exhibit color graining, which is considered an inclusion.

The colored and reflective graining in this light brownish purple-pink diamond is visible under 40-power magnification.
Cut
Size and shape are two aspects of cut that can influence diamond color. The larger a diamond is, or the deeper its pavilion, the farther light can travel in it. This can often lead to a richer, more intense color.

The style of the cut can also influence color. Cutters discovered that certain styles—typically mixed cuts like the radiant—can intensify yellow color in diamonds that are toward the lower end of the D-to-Z color-grading scale. When carefully fashioned as radiant cuts, many yellow-tinted stones—at one time called “cape” by the trade—can become fancy yellows when viewed face up. This perceived improvement in color increases the price per carat. As an added benefit, the radiant style provides higher yield from the rough than a standard round brilliant.

	Fancy color diamonds are often cut into fancy shapes.
Carat Weight
As with diamonds in the normal D-to-Z color range, large fancy color diamonds are rarer and more valuable than small ones.

	The Vagabonde Jaune ring features small white and yellow diamonds surrounding a 10.81-carat yellow diamond. - Vagabonde Jaune Ring © 2011 Fabergé Ltd Source: GIA @topic:4


Title: Fancy Color Diamond History and Lore Abstract: The 5.03-carat DeYoung Red is an exceptionally rare colored diamond. Chip Clark, - Courtesy Smithsonian Institution, National Museum of Natural History.

                      The world’s first diamond color-grading system dates back to sixth-century India. The system was based on the country’s ancient class structure. Members of different status levels, or castes, were permitted to own and wear only diamonds of a specific color. Thus, diamonds served as a badge of rank.

The priests and rulers, the Brahmins, were allowed to own diamonds that were “whitest of the conch, of the lotus, or of the rock crystal” (white to colorless). The landowners and warriors were assigned diamonds that were “the brown color of the eye of the hare.” The merchant class was allowed to own only diamonds that were the “pretty nuance of a petal of a kadl [flower]” (yellow). And members of the lower classes were assigned diamonds with “the sheen of a burnished sword” (gray or black). Kings, however, were free to possess diamonds of any color.

Diamond color-grading systems have evolved a lot since that time. Today, there are well-established methods for judging diamond color based on much more than a comparison to conch shells, rabbits’ eyes, and flower petals. And the only restrictions to owning different colors are based on availability and affordability.

While fancy color diamonds have traditionally been a small part of the diamond business, their popularity and availability have grown in the past several decades. In the 1980s the Argyle mine in Australia began marketing its brown stones under trade names like “Champagne” and “Cognac.” Argyle reached its goal of making the public more aware of fancy color diamonds and dropped its marketing campaign in the late 1990s. Today, the Argyle mine still produces brown diamonds, but it’s more famous as the world’s major source of rare pink diamonds.

	These rare pink and violet diamonds make up a tiny but important fraction of the Argyle mine’s production. - Courtesy Rio Tinto Diamonds
The most well-known historical and current sources of fancy color diamonds are India, South Africa, and Australia. Other diamond mine locations, including Brazil, Venezuela, Guyana, and Indonesia, also produce fancy color diamonds.

	Brownish diamonds, like these crystals and round brilliants, constitute the bulk of
	Argyle’s production. Source: GIA @topic:4


Title: Hong Kong Jewelry Show: The World’s Largest Assemblage of Cultured Pearls Abstract: More than 1,200 metric tons of freshwater cultured pearls were produced in China in 2011. Buttons, rounds, semi-rounds, and lower-quality dyed pearls at this Chinese wholesaler's booth at the 2012 Hong Kong Jewelry Show are typical of that production. Photo by Russell Shor

                      Cultured pearls are farmed all over the Pacific Rim and the rivers and lakes of China. Regardless of origin, the vast majority—South Sea, akoya, French Polynesian black, or golden from the Philippines—are sold through Hong Kong.

	A river of cultured pearls of all sizes and varieties was on display at the 2012 show, the
	largest of its kind in the world. Photo by Russell Shor.
Nowhere is that more evident than at the Hong Kong Jewellery and Gem Fair, held in mid-September each year. The show takes place in two venues, the Asia World Expo near the airport and the Hong Kong Convention & Exhibition Centre in the heart of the city, and thousands will flock to there to buy and sell once again Sept. 11–17, 2013.

	This assortment of Chinese freshwater cultured pearls shows the wide variety of sizes and colors sold at the 2012 Hong Kong Jewellery and Gem Fair. Photo by Russell Shor.
Nearly 1,000 pearl wholesalers assemble in a dedicated PearlPavilion at the Asia World Expo , which is the largest accumulation of cultured pearls in any single place. Top brands also show their finest merchandise at the Hong Kong Premier Pavilion in the convention center. Many of the major saltwater pearl producers, including Paspaley Pearling Company and Robert Wan, auction their new goods in conjunction with the show. Source: GIA @topic:15


Title: Trapiche Gems Abstract: Figure 1. A pair of trapiche emerald slices from Colombia, 10.92 carats total. Photo by Kevin Schumacher; courtesy of Mayer & Watt.

Jeffery Bergman is known in the trade as a collector of trapiche gems. These gems, characterized by their six-rayed patterns, are elusive and seldom found in high quality. Mr. Bergman believes people are attracted to the symmetrical pattern, which reflects a natural order in the chaotic world we live in. According to Bergman, trapiche gems are too rare to support a business, so he has also traded many other gemstones during his 50-year career.

	Jeffrey Bergman discusses trapiche gems

As with most gemologists, the first trapiche gems he saw were Colombian emeralds. But it wasn’t until 10 years after this initial encounter at the Tucson gem show that he purchased his first trapiche gemstone: a thick Colombian emerald weighing about 20 ct. Mr. Bergman sliced it in two, increasing the value after it became a matched pair of acceptable thickness.
He saw his first non-emerald trapiche gems at the Mae Sot gem market on the Thai-Burmese border in the early 2000s. Mr. Bergman was handed three Burmese trapiche sapphires from Mogok, something he never knew existed. Other collectors were equally surprised and paid high amounts for these stones, encouraging Mr. Bergman to expand his collection. During those days, many fine Burmese trapiche rubies came out of Mong Hsu while Mogok provided the trapiche sapphires.
Trapiche rough is extremely difficult to judge since the patterns often do not extend throughout the entire stone. In most cases, the most desirable pattern can only be found in the middle of the crystal length.
Trapiche and non-trapiche emerald evaluation are very similar, as the most important characteristics are always the color and transparency of the emerald itself (figure 1). The symmetry and shape of the pattern are only of secondary importance, followed by size and potential treatments.
Trapiche emeralds from Colombia are well known, with the Muzo mine producing the majority. The patterns can exhibit many variations, from perfect six-ray symmetry with high clarity to cloudy stones with broken or incomplete rays. Trapiche-like emeralds have recently been found in Swat, Pakistan, but they show a very different appearance and formation (Fall 2019 GNI, pp. 441–442). Beryls such as aquamarine and bixbite (red beryl) are known to exhibit trapiche or trapiche-like characteristics but they are even rarer than emeralds.
Trapiche corundum gems are mostly known from Myanmar. Trapiche ruby from Mong Hsu is often small. In his 20 years of trapiche experience, Mr. Bergman has only encountered two gem trapiche rubies from Mong Hsu that were over 1 carat. The material is fairly dark, which means it must be sliced thin to appreciate any color, thus reducing the weight of the stone drastically. Heat treatment rarely improves the appearance; it alters the trapiche pattern, making it chalkier and less pronounced.
The Tajik ruby mines have also produced trapiche rubies, as well as the mines in Nepal. Batakundi (Pakistan) and Orissa (India) are other sources of ruby with six-rayed patterns (Spring 2019 G&G  Micro-World, p. 114).

Figure 2. Trapiche sapphire from Mogok, Myanmar. This stone shows a regular pattern of snow white and blue zones. Photos by Kevin Schumacher.
Trapiche sapphires from Mogok (figure 2) are often dominated by gray tones or very saturated blues bordering black colors. Only the finest stones show a snow-white bodycolor with vivid blue arms. To date, these are the only true trapiche sapphires. Trapiche-like sapphires are much more common from basalt-related sources such as southern Vietnam, Australia, and even lesser-known areas such as Scotland.
Quartzes, including amethyst and smoky quartz, can exhibit trapiche patterns. A pocket of Zambian tourmalines and some extremely rare garnets also show a six-rayed pattern.
In Mr. Bergman’s opinion, trapiche only applies when the symmetry is sixfold. This excludes more common materials with similar growth patterns like chiastolite. Asteriated diamonds, most often found in Zimbabwe, resemble trapiche when viewed in certain angles, but in reality they contain clouds extending in three dimensions at 90º angles.
In the last decades, knowledge and appreciation of these unique stones has spread and they are now actively sought after by collectors, bespoke designers, and gem enthusiasts. This increased demand and availability has driven gemologists to take a deeper look at these gems and their formation, but there remains much to be discovered. Source: GIA @topic:1


Title: Gem Characterization Abstract: Figure 1. Measuring about 7 cm across, this 404.2 ct rough from Angola’s Lulo mine is a good example of the irregular shape and surface texture associated with CLIPPIR diamonds. The unusual characteristics of diamonds like this one are the result of formation in a unique geological setting. Once cut, this rough yielded a 163.4 ct flawless D-color diamond. Photo by Jian Xin (Jae) Liao.

The Formation of Natural Type IIa and IIb Diamonds
Evan M. Smith and Wuyi Wang
GIA, New York
Many of the world’s largest and most valuable gem diamonds exhibit an unusual set of physical characteristics. For example, in addition to their conspicuously low nitrogen concentrations, diamonds such as the 3,106 ct Cullinan (type IIa) and the Hope (type IIb, boron bearing) tend to have very few or no inclusions, and in their rough state they are found as irregular shapes rather than as sharp octahedral crystals. It has long been suspected that type IIa and IIb diamonds form in a different way than most other diamonds.
Over the past two years, systematic investigation of both type IIa and IIb diamonds at GIA has revealed that they sometimes contain rare inclusions from unique geological origins. Examination of more than 130 inclusion-bearing samples has established recurring sets of inclusions that clearly show many of these diamonds originate in the sublithospheric mantle, much deeper in the earth than more common diamonds from the cratonic lithosphere. We now recognize that type IIa diamonds, or more specifically, diamonds with characteristics akin to the historic Cullinan diamond (dubbed CLIPPIR diamonds), are distinguished by the occurrence of iron-rich metallic inclusions. Less frequently, CLIPPIR diamonds also contain inclusions of majoritic garnet and former CaSiO3 perovskite that constrain the depth of formation to within 360–750 km. The inclusions suggest that CLIPPIR diamonds belong to a unique paragenesis with an intimate link to metallic iron in the deep mantle (Smith et al., 2016, 2017). Similarly, findings from type IIb diamonds also place them in a “superdeep” sublithospheric mantle setting, with inclusions of former CaSiO3 perovskite and other high-pressure minerals, although the iron-rich metallic inclusions are generally absent (Smith et al., 2018). Altogether, these findings show that high-quality type II gem diamonds are predominantly sourced from the sublithospheric mantle, a surprising result that has refuted the notion that all superdeep diamonds are small and non-gem quality. Valuable information about the composition and behavior of the deep mantle is cryptically recorded in these diamonds. CLIPPIR diamonds (figure 1) confirm that the deep mantle contains metallic iron, while type IIb diamonds suggest that boron and perhaps water can be carried from the earth’s surface down into the lower mantle by plate tectonic processes. In addition to being gemstones of great beauty, diamonds carry tremendous scientific value in their unique ability to convey information about the interior of our planet.
REFERENCES
Smith E.M., Shirey S.B., Nestola F., Bullock E.S., Wang J., Richardson S.H., Wang W. (2016) Large gem diamonds from metallic liquid in Earth’s deep mantle. Science, Vol. 354, No. 6318, pp. 1403–1405, http://dx.doi.org/10.1126/science.aal1303
Smith E.M., Shirey S.B., Wang W. (2017) The very deep origin of the world’s biggest diamonds. G&G, Vol. 53, No. 4, pp. 388–403, http://dx.doi.org/10.5741/GEMS.53.4.388
Smith E.M., Shirey S.B., Richardson S.H., Nestola F., Bullock E.S., Wang J., Wang W. (2018) Blue boron-bearing diamonds from Earth’s lower mantle. Nature, Vol. 560, No. 7716, pp. 84–87, http://dx.doi.org/10.1038/s41586-018-0334-5
Colored Diamonds: The Rarity and Beauty of Imperfection
Christopher M. Breeding
GIA, Carlsbad, California
Diamond is often romanticized as a symbol of purity and perfection, with values that exceed all other gemstones. However, even the most flawless and colorless natural diamonds have atomic-level imperfections. Somewhat ironically, the rarest and most valuable gem diamonds are those that contain abundant impurities or certain atomic defects that produce beautiful fancy colors such as red, blue, or green—stones that can sell for millions of dollars per carat.
Atomic defects can consist of impurities such as nitrogen or boron that substitute for carbon atoms in the diamond atomic structure (resulting in classifications such as type Ia, type Ib, type IIa, and type IIb) or missing or misaligned carbon atoms. Some defects are created during diamond growth, while others are generated over millions to billions of years as the diamond sits deep in the earth at high temperatures and pressures. Defects may be created when the diamond is rapidly transported to the earth’s surface or by interaction with radioactive fluids very near the earth’s surface. Each defect selectively absorbs different wavelengths of light to produce eye-visible colors. Absorptions from these color-producing defects (or color centers) are detected and identified using the gemological spectroscope or more sensitive absorption spectrometers such as Fourier-transform infrared (FTIR) or ultraviolet/visible/near-infrared (UV-Vis-NIR; figure 1). Some defects not only absorb light but also produce their own luminescence, called fluorescence. For example, the same defect that produces “cape” yellow diamonds also generates blue fluorescence when exposed to ultraviolet light. In some cases, the fluorescence generated by defects can be strong enough to affect the color of gem diamonds.

Figure 1. Visible-NIR spectra reveal the absorptions and corresponding atomic defects responsible for the color in gem diamonds.
With the exception of most natural white and black diamonds, where the color is a product of inclusions, colored diamonds owe their hues to either a single type of defect or a combination of several color centers. More than one type of defect can produce a particular color, however. Table 1 provides a list of the most common causes of color in diamond.

Subtle differences in atomic defects can drastically affect a diamond’s color. For example, isolated atoms of nitrogen impurities usually produce strong yellow color (“canary” yellow diamonds). If those individual nitrogen atoms occur together in pairs, no color is generated and the diamond is colorless. If instead the individual nitrogen atoms occur adjacent to missing carbon atoms (vacancies), the color tends to be pink to red. Rearrangement of diamond defects is the foundation of using treatments to change the color of diamond. Identification of treatments and separation of natural and synthetic diamond requires a thorough understanding of the atomic-level imperfections that give rise to diamond color and value.
Evaluating the Color and Nature of Diamonds Via EPR Spectroscopy
Haim Cohen1 and Sharon Ruthstein2
1Ariel University and Ben-Gurion University of the Negev, Israel
2Bar-Ilan University, Israel
Diamond characterization is carried out via a wide variety of gemological and chemical analyses. An important analytical tool for this purpose is spectroscopic characterization utilizing both absorption and emission measurements. The main techniques are UV-visible and infrared spectroscopy, though Raman as well as cathodoluminescence spectroscopy are also used.
We have used electron paramagnetic resonance (EPR) spectroscopy to compare the properties of treated colored diamonds to the pretreated stones. The colors studied were blue, orange, yellow, green, and pink. The EPR technique determines radicals (atoms with unpaired electrons) and is very sensitive, capable of measuring concentrations as low as ~1 × 10–17 radicals/cm3. The results, shown in table 1, indicate that all the carbon radicals determined are affected by adjacent nitrogen atoms, with the spectra showing a hyperfine structure attributed to the presence of nitrogen. The highest concentration of radicals and hyperfine structures is observed in pink and orange treated diamonds. The results concerning nitrogen concentration were correlated with the infrared spectra, which determine the absorption peaks of the diamonds as well as those of the nitrogen contamination in their crystal structure.

Quantitative Absorption Spectrum Reconstruction for Polished Diamond
Roman Serov (presented by Sergey Sivovolenko)
OctoNus Software, Moscow
Natural diamonds generally exhibit a very wide range of spectra. In polished stones, absorption along with proportions and size define perceived diamond color and thus beauty.
In rough diamonds, the quantitative absorption spectrum (the “reference spectrum” in the context of this article) can be measured using an optical spectrometer through a set of parallel windows polished on a stone, so the diamond can be considered a plane-parallel plate with known thickness.
Polished diamonds lack the parallel facets that might allow plane-parallel plate measurement. That is why polished diamond colorimetry uses one of two approaches that have certain limitations for objective color estimation:

Qualitative spectrum assessment with an integrating sphere. Suppose three diamonds are polished from a yellow rough with even coloration: a round (with short ray paths), a cushion (with high color uniformity and long ray paths), and a “bow tie” marquise (with both long and short ray path areas). The spectra captured from these three stones by an integrating sphere will be completely different because the ray paths are very different. However, the quantitative absorption spectrum will be the same for all three stones, since they are cut from the same evenly colored rough. Therefore, spectrum assessment with an integrating sphere has very limited accuracy and is practical for qualitative estimations only.
Analysis of multiple images of a diamond made by color RGB camera. This method has low spectral resolution defined by digital camera color rendering. The camera has a smaller color gamut than the human eye, so most fancy-color diamonds are outside the color-capturing range of a digital camera.

However, quantitative absorption data is very valuable for:

Color prediction and optimization for a new diamond after a recut process
Objective color assessment and description of a polished diamond

This paper presents a new technology based on spectral light-emitting diodes (LEDs) and high-quality ray tracing, which together allow the reconstruction of a quantitative absorption spectrum for a polished diamond. The approach can be used for any transparent polished diamond. The recent technology prototype has a resolution of 20–60 nm, which is practical for color assessment. Figure 1 (top) presents three photorealistic diamond images: A is based on the reconstructed absorption spectrum collected from a polished diamond, B uses the reference spectrum collected in the rough stage through a pair of parallel windows, and C uses the averaged reference spectrum. Figure 1 (bottom) shows both measured quantitative absorption and reconstructed absorption spectra.

Figure 1. Top: Photorealistic diamond images generated from the reconstructed absorption spectrum (A), the reference spectrum (B), and the averaged reference spectrum (C) of the same stone. Bottom: Quantitative and reconstructed absorption spectra.
This technology has the potential to ensure very close to objective color estimation for near-colorless and fancy-color polished diamonds. The reconstructed spectrum resolution can be enhanced to 10–15 nm in future devices. Source: GIA @topic:7