Publication Year: 2018 Title: Preview of Nature Art Science with Paula Crevoshay Abstract: Figure 1. Left: Paula Crevoshay's Siberian tigress Baianai incorporates aquamarine eyes with black diamond pupils, 286 white diamonds, 168 cognac diamonds, and a 1.05 ct pink Oregon opal in 18K gold. Right: The Morning Glory brooch contains 272 Yogo sapphires, 90 purple sapphires, 45 pink sapphires (2.75 carats), and a 2.92 ct central moonstone, all in 18K gold. Photos by Kevin Schumacher.
Paula Crevoshay described 2018 as an “opulent year” and showed us several new pieces that celebrate nature. Her remarkable use of color draws in and enchants the viewer. She is working on a museum exhibition concept entitled Nature Art Science, with the intent of capturing how art is inspired by nature and how science is essential in the execution of art. Her work illustrates this concept, as the lifelike flora and fauna creations maximize the use of color and light while being solidly engineered and highly versatile.

Crevoshay displayed several realistic pieces depicting endangered animals, including the Siberian tigress Baianai (figure 1, left), whose mesmerizing eyes are composed of aquamarine with black diamond pupils. Baianai’s nose is a hand-carved pink Oregon opal, and the rest of the 18K yellow gold jewel contains 286 white and 168 cognac diamonds.  The hardware is engineered to allow the piece to be worn in many different ways. There are lush new flowers from Crevoshay such as the Morning Glory brooch (figure 1, right), which draws the observer into its center with an adularescent moonstone surrounded by a sea of 272 blue Yogo sapphires. The hue shifts toward purple and pink with the use of 90 lavender and 45 fuchsia sapphires from the tips of the petals to the center.

New Work from Paula Crevoshay
Celebrated designer Paula Crevoshay explores the themes behind some of her more recent work.
Crevoshay’s first cuff of 2018 (figure 2, left) is titled Moon Glow and features moonstones as well as blue zircon, iolite, and blue sapphire. She likened it to “painting with light.” Another piece that spoke to this concept was a pendant containing a large and exceptionally fine 30.64 ct Ethiopian opal (figure 2, right). The flanking of the opal’s intense play-of-color hues with like-colored surrounding stones such as blue zircon, pink tourmaline, tsavorite garnet, apatite, and ruby made for a stunning and very aesthetically pleasing piece. Both works showcased many of the most popular hues we observed throughout the AGTA show.

Figure 2. Left: Crevoshay's Moon Glow cuff contains 72.28 carats of moonstone, 36.68 carats of blue zircon, 8.58 carats of iolite, and 3.47 carats of blue sapphire in 18K gold. Right: The Gelila pendant features a 30.64 ct Ethiopian opal surrounded by blue zircon, pink tourmaline, tsavorite, apatite, ruby, and diamond melee. Photos by Albert Salvato.
Talking with the artist, we learned that her father was an engineer, an exposure that led her to design all of her own mechanisms (such as hinged bales), allowing the pieces to be worn in many ways, such as a pendant or brooch. From an artistic standpoint, Crevoshay has drawn inspiration from Schlumberger, Fabergé, and Lalique. Their influence is evident in her designs that are simultaneously intricate and fluid, while focusing on the use of light with the color of the incorporated materials. From the mesmerizing and magnificent details such as the hand-carved Oregon pink opal nose of her tigress to side stones mimicking the play-of-color of a precious opal, it is easy to understand why her work has attracted such a following. @chapter:26


Publication Year: 1987 Title: An Update on Color in Gems. Part 1: Introduction and Colors Caused by Dispersed Metal Ions Abstract: Studies concerning the origin of color in gem materials have grown in sophistication in recent years, so that much new information is now available about natural color and its possible modification by various treatment processes. This three-part series of articles reviews our current understanding of gemstone coloration. The first part summarizes the factors that govern the perception of color, from the source of light to the human eye, and then examines in detail the role of one color-causing agent, dispersed metal ions, in the coloration of many gem materials, including ruby and emerald. The second part will explore charge-transfer phenomena and color centers as the cause of color in gems such as blue sapphire and Maxixe beryl. The series will conclude with colors that can be explained using band theory and physical optics, such as the play-of-color in opal and the blue sheen of moonstone feldspars. @chapter:9


Publication Year: - Title: Designer’s ‘Complex, Eccentric’ Pieces Create Buzz, Find Fans in Hollywood and D.C. Abstract: Christina Fandino's kinetic “The Spider & the Egg” ring-palm bracelet took first-place honors in the Metal Arts Society of California’s 2017 Jewelry Challenge. “The body of the spider rotates 360 degrees, the legs move at the ball and socket joints, and the egg gently spins within its web cradle,” she says. The piece features two amethysts and a 1 ct moldavite. Courtesy of Christina Grace/TIN HAUS

Christina Fandino’s career has been nothing short of a whirlwind since 2015.

In that brief span of time, the Los Angeles designer, who also is known as Christina Grace, won a life-changing scholarship, designed a necklace that drew buzz during the presidential elections, and established a company that’s both earning national press coverage and finding fans among Hollywood A-listers.

Fandino, a GIA Graduate Jeweler, is also winning awards, including first-place honors in the Metal Arts Society of California’s 2017 Jewelry Challenge, for a kinetic, ring-palm bracelet called “Spider & Egg.”

“The body of the spider rotates 360 degrees, the legs move at the ball and socket joints, and the egg spins within its web cradle,” explains Fandino, who calls her artistic aesthetic “diverse” and “eccentric.” The piece, along with a painting created by Fandino, was also recently selected as a finalist in the Boone Art Gallery’s Annual Juried Exhibition, and was on display at the gallery in Pasadena through January 2018.

TIN HAUS Founder Christina Fandino, GJG, began her career in the fine arts, focusing on painting and acting. She won a scholarship to GIA in 2015 and her jewelry design career has been a whirlwind ever since. Photo by Philipp Harth. Courtesy of Christina Grace/TIN HAUS
Until just a few years ago, Fandino’s career in the fine arts was focused on painting and acting. Her family immigrated to the United States from Manila, Philippines in the mid-1980s, eventually settling in Oceanside – a coastal city north of San Diego. Fandino describes herself as an artist “from the start,” and entered competitions from a young age.

She continued to sell paintings privately as she grew, though her art took the direction of acting for years – she appeared in TV shows, independent movies and feature films, such as Anne Hathaway and Jake Gyllenhaal’s “Love & Other Drugs.” Jewelry was not on her radar as a profession or method of creative expression, even though she knew more about it than the average consumer and enjoyed collecting stones as a child.

“My family did not come from a jewelry background, but my mother was the poster child for jewelry obsession,” she says. “I learned a lot about jewelry because of her influence. By 9, I already knew what the 4Cs were, and what a diamond-cut chain looked like. I was proud to know the difference between ‘carat’ and ‘karat.’ I had an appreciation for metals and was an avid collector of raw crystals and stones.

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“I heard about GIA frequently from a young age,” she says, “I grew up informed that it’s where you went to get jewelry training, but didn’t understand how much it would later instrumentally influence my life.”

In 2011, that changed when she had a “chance meeting” with a jewelry store owner who taught her wire-wrapping techniques.

“That’s when I fell in love with the creation of jewelry,” Fandino says. “Once I fell in love with jewelry-making, I knew I had to go to GIA.”

She was finally able to apply to the Institute in 2015, and found out that she would also receive a scholarship.

“I felt like I shot to the moon and back!” she says. “A GIA scholarship afforded me the opportunity to go to the institution I’d looked up to growing up, and gave me the confidence to pursue this new path without holding back. It was truly humbling and an honor.”

A self-described “perfectionist,” Fandino says she tried to absorb everything she could while studying in Carlsbad.

“I felt like there was so much to learn,” she says. She spent lots of time talking with her instructors, getting suggestions from librarians at the Richard T. Liddicoat Gemological Library and Information Center and utilizing the resources of Career Services.

Fandino, GJG, at her 2016 GIA graduation in Carlsbad. “The GIA scholarship afforded me the opportunity to go to the institution that I looked up to, growing up,” she says. “It gave me the confidence to pursue this new path without holding back.” Photo by Cedric Jonathan. Courtesy of Christina Grace/TIN HAUS
In the midst of an already-busy year, Fandino also founded TIN HAUS fine arts company with her partner Cedric Jonathan, who still directs the company’s sales and marketing efforts.

“Our drive was led by one goal – to use our gifts and talents for change,” she says. “Through the company, we have been able to donate a portion of the profits towards causes and non-profit organizations we care about and are deeply passionate about.”

One of those causes was the campaign for 2016 U.S. presidential hopeful Bernie Sanders. While still a student at GIA, Fandino designed and hand-fabricated a pendant featuring Sanders’ iconic hair, glasses and silhouette. The “The Bern Necklace” got Sanders’ wife, Jane’s, attention, and soon orders were coming in to TIN HAUS almost as quickly as Fandino could keep up.

Bernie Sanders’ wife, Jane, endorsed then-GIA student Christina Fandino’s “The Bern Necklace,” a hand-fabricated representation of the 2016 presidential candidate’s iconic hair and silhouette. Orders poured in from across the United States and Fandino donated a portion of the profits to support his campaign. Courtesy of Christina Grace/TIN HAUS
Fandino moved back to Los Angeles after her GIA graduation, working as a master jeweler and design consultant for a Beverly Hills firm before she realized she wanted her work to truly be her own.

“I wanted to channel all of my good, artistic energy toward stretching my craft by way of school and expanding TIN HAUS,” says Fandino, who is earning her Bachelors of Fine Arts in Metals at California State University. “And due to the intensive training I received from GIA’s Graduate Jeweler program, I’ve experienced leaps and bounds creatively and professionally.”

Fandino has since won several more scholarships for her work, and the professional momentum gained with “The Bern Necklace” hasn’t let up.

Fandino created the "Film, I AM" pendant for the cast and crew of the 2017 Make a Film Foundation’s production, “The Black Ghiandola.” The sterling silver pendant, which features a 3 mm moldavite, will be expanding as a production line in 2018. Courtesy of Christina Grace/TIN HAUS
Her designs have been featured in Maxim and Flaunt magazines, and her acting and jewelry worlds also collided when Fandino was asked to be the official jeweler of the Make a Film Foundation (MAFF), a nonprofit organization that helps terminally ill young people realize their filmmaking dreams. When MAFF recently helped a 16-year-old cancer patient direct a movie starring Johnny Depp, Laura Dern, David Lynch and J.K. Simmons, Fandino made sterling silver pendants for the cast and crew – including directors Catherine Hardwicke, Sam Raimi and Theodore Melfi – as a thank you for loaning their time and talents.

That pendant, named the “I AM,” is set to be the cornerstone of a larger collection – the first full line – launched by TIN HAUS later in 2018.

“The process of creation is what fuels my fire,” she says. “I’m an artist with complex and eccentric ideas, and I don’t watch what other people are doing. If I was encumbered by that, I wouldn’t get anything done, and my work would start to look like everything else you see out there. Concepts and ideas should come from a deeper place – I believe in creating from the heart first, and the fruits of your labor will follow.” @chapter:16


Publication Year: 2016 Title: Ring with a CVD Synthetic Melee Diamond Abstract: Figure 1. One of the round-cut melee mounted in this ring was identified as a CVD synthetic diamond. Photo by Johnny Leung.

The separation of synthetic diamond melee from natural diamond melee is a significant concern. Some specimens have been identified by GIA and other laboratories as synthetic, but those products were predominantly HPHT grown. GIA’s Hong Kong lab recently identified a CVD synthetic melee mounted in a ring (figure 1).

The round-cut synthetic measured approximately 2.8 mm in diameter and weighed about 0.08 ct. Color could not be graded due to the mounting, but it was estimated to be in the F-H range. The material showed no notable visual features using the microscope other than a small surface scratch at the table. Infrared absorption spectroscopy indicated the typical features of a type IIa diamond; no defect-related absorption feature was detected. A PL spectrum was collected at liquid nitrogen temperature with a very wide range of laser excitation wavelengths. Major features included emissions from [N-V] and [Si-V]– centers (figure 2). The emission at 575.0 nm from [N-V]0 is much stronger than the peak at 637.1 nm from [N-V]–, similar to many natural type IIa diamonds. Most notably, this specimen showed very strong emissions at 736.6 and 736.9 nm from the [Si-V]– defect. Using 514 nm laser excitation, the intensity of the [Si-V]– defect was about eight times that of the diamond Raman line. DiamondView imaging revealed strong orange color with small irregular areas of blue fluorescence (figure 3). All these observations confirmed that this melee is an as-grown CVD synthetic.

Figure 2. The photoluminescence spectrum collected at liquid nitrogen temperature with
514 nm laser excitation shows moderate emissions from [N-V] centers and a very strong
emission from [Si-V]–.

Figure 3. DiamondView imaging showed strong orange fluorescence with small irregular areas of blue fluorescence, a typical feature of as-grown CVD synthetic diamond. Photo by Carmen Lo.
This was the first mounted CVD synthetic melee diamond identified by GIA. While synthetics of this size are overwhelmingly HPHT grown, we do expect to see more CVD synthetic diamond melee in the future. @chapter:15


Publication Year: - Title: Let Jewelry Tell the Story: An Interview with Chinese-Style Designer Yue-Yo Wang Abstract: Jewelry designer Yue-Yo Wang, from Taiwan, is the founder of Wang Yue-Yo Creative Jewelry Design. Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

                      China has a long history of jewelry design. For thousands of years, the Chinese people have used jewelry for self-adornment. Today, more and more western designers are implementing oriental elements into their jewelry.

Yue-Yo Wang, a jewelry designer from Taiwan, has devoted herself to traditional Chinese jewelry design. She has combined the Chinese knotting art with modern jewelry design and manufacturing techniques to create her own pieces. Every finished piece has its own story.

	Yue-Yo’s designs feature large, high-quality materials, applied in the “Chinese Style.”
	Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

	Chinese Knotting Art
In China, knotting art can be traced back to around 1600 BC. Before that time, knotting had a more practical purpose, which was to record important events or numbers on a daily basis. After that, with the development of written record-keeping, knotting gradually lost its practical purpose and became more decorative.

Chinese knotting art experienced a peak from around 600 AD until the early 1900s. Along with most of the other arts, its development paused during a 100-year span of social upheaval in China. Currently, knotting is being picked up once more by younger generations, who have developed a high appreciation for this ancient art. Knotting threads are made of a variety of materials. Knotting art can be used for room decorations or jewelry pieces. China has even established qualifying exams at different levels for experienced knot makers.

At one time, Yue-Yo enjoyed a very relaxed and easy life as a housewife and collector of Chinese artistic teapots. When an unforeseen event affected her husband’s business, her easy life ended and she had to start making an income. She began a small business to sell her teapot collection along with some of her knotted teapot covers.

She gradually fell in love with knotting and decided that she could use it to add to her profits. She spent time developing her knotting skills and, after a short period of time, became a well-known knot maker. People advised her to establish a knotting art education program and many students came to learn from her, some of them from overseas.

Although knotting products and classes increased her profits, they still required a lot of labor and sold for relatively low prices. She often had to work extra hours or overnight to complete orders. This situation inspired her to look for a more efficient way to add value to her products. She tried using knotting techniques on clothes, decorations, and other articles. Then she came up with the great idea of combining knotting art with modern jewelry manufacturing methods.

She was not yet a jewelry designer, so she passed most of the knotting work to her students and set out to learn jewelry design. Accomplishing this turned out to be a great advantage for her jewelry company, which was very successful even when the global economy was suffering.

	Knotted thread was used to create the wrapping band on this jewelry piece.  Photo
	courtesy of Wang Yue-Yo Creative Jewelry Design

	The headquarters of Wang Yue-Yo Creative Jewelry Design in Taipei. Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

	Personal and Company Growth
Yue-Yo has been part of the jewelry design industry for about 20 years. In that time, her company has experienced several important development stages.

From 1993 to 1999, Yue-Yo Wang Creative Jewelry Design concentrated on promoting the design concept of “Chinese style” jewelry. They participated in many large international jewelry shows to attract international consumers and build the company image. From 2000-2005, Yue-Yo and her colleagues increased their participation in a variety of social works while further developing their jewelry design and manufacturing techniques.

Around 2005, she sensed the rapid development and huge potential of the mainland China jewelry market. She and her team headed west to explore this major market. So far, since then they have opened more than 10 stores all over mainland China, including their guild store, which opened in 2007 in Beijing. In 2008, Yue-Yo was asked by Beijing Shanyuan Jewelry Company to jointly design the Beijing Olympics souvenir crystal dragon stamp. This event gave her and her designs more public exposure and also made her more confident about the future of “Chinese style” jewelry.

In 2012, Yue-Yo turned another dream into reality by forming the Taiwan Creative Jewelry Design Association. She hopes that this organization will attract more jewelry designers who focus on artistic jewelry design and would like to spread the Chinese culture to the rest of the world.

	Yue-Yo designs not only jewelry, but also “Chinese style” clothing. Her jewelry and clothes go perfectly together.  Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

	This is the exterior of the company’s guild store in Beijing. Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

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	This slideshow exhibits representative Chinese style jewelries as designed by Yue-Yo Wang.

	Jewelry Design Concepts and Inspirations
A careful look at Yue-Yo’s design always reveals some traditional Chinese symbols and some elements from Chinese knotting art, like long tassels and thread patterns The main focus of her designs is to combine different symbols to create a scene or a story.

	Birds, flowers, tassels, and Chinese character patterns are common elements in
	Yue-Yo’s designs. Photo courtesy of Wang Yue-Yo Creative Jewelry Design.
Yue-Yo’s designs are usually inspired by the stones in her hands. She believes that every gem has its own spirit, and she is inspired to find it and express it to people. Since her main business is now high-end customized design for consumers, she pays a lot of attention to the quality of the gem materials and the manufacturing details of her jewelry. She employs her own jewelers, so it is very easy for her to work with them and pass along her ideas to them. Some of her jewelers have more than 30 years of experience in the industry.

Materials that she uses most commonly in her designs include opal, coral, jadeite, tourmaline, and chalcedony. She likes coral the most, because coral is one of the three symbolic gems of Taiwan. Before, rough coral was often exported to Japan and other countries to be carved, so she felt that the Taiwanese did not take full advantage of their own gems.

She began to use coral in her knotting projects, attracting respect and appreciation from coral dealers. Then she found that the real high-quality corals are not fit for knotting because holes usually needed to be made. She now uses other high-quality material in her high-end design products.

	High-quality coral from Taiwan is Yue-Yo’s favorite gem material to use in her haute couture products. Photo courtesy of Wang Yue-Yo Creative Jewelry Design.

	Passing Skills to the Next Generation
Yue-Yo Wang is not just a designer; she is also a great instructor. She enjoys talking to young people. At every jewelry show she participates in, she likes to talk to young students who want to be jewelry designers.

She still teaches knotting and jewelry design to young people (Fig.9). Many of her students started good careers after being trained and helped by her. In the future, she plans to work more on jewelry design education and the spread of Chinese culture, working through her own company and the organization she formed.

	Yue-Yo teaches jewelry design students in order to pass her design skills to the next generation. Photo courtesy of Wang Yue-Yo Creative Jewelry Design. @chapter:16


Publication Year: 2023 Title: Pink Sapphire with Graphite Inclusion Abstract: This pristine hexagonal platelet of graphite was seen in a pink sapphire from Sri Lanka. Photomicrograph by Jeffrey Hernandez; field of view 1.99 mm.
Graphite inclusions in corundum can occur as minute bodies inside negative crystals alongside trapped diaspore and carbon dioxide. They can also appear as separate large metallic-looking hexagonal plates or jumbled clusters of small flaky crystals. Graphite in sapphire commonly occurs in those from Sri Lanka or Batakundi, Pakistan (V. Pardieu et al., “Sapphires reportedly from Batakundi/Basil area,” GIA Research News, May 12, 2009). The author recently found a surprisingly well-formed hexagonal graphite platelet with surface etchings in a pink sapphire from Sri Lanka (see above). Taking into account the luster and structure of the inclusion in this particular stone, it was identified as graphite under the microscope.
Graphite is a stable form of layered carbon occurring as a submetallic opaque mineral with a black to steel-gray color range. It typically forms in carbon-rich metamorphic rock or in pegmatite. Formation of this inclusion is dependent on the grade of metamorphism and temperature in the growth environment. It is rare to find such a clean example of a singular graphite inclusion demonstrating the crystal system it belongs to. This graphite inclusion in pink sapphire was a remarkably pristine example of this inclusion and host relationship. @chapter:19


Publication Year: 2018 Title: Perettiite-(Y) and Tusionite Inclusions in Phenakite from Myanmar Abstract: Figure 1. Left: Perettiite-(Y) bundle in phenakite from Khetchel, Myanmar; image width 3.8 mm. Right: Tusionite plates in phenakite from Khetchel; image width 2.5 mm. Photomicrographs by P. Škácha.
Every year about 100 new minerals are described, but few have been discovered as inclusions in gemstones (e.g., carmichaelite in chrome pyrope from Arizona and protoenstatite in labradorite from Oregon). In 2015, a new mineral—perettiite-(Y)—was described as inclusions in phenakite crystals from pegmatites by Khetchel village in the Molo area near Momeik, about 100 km northeast of Mogok (R.M. Danisi et al., “Perettiite-(Y), Y3+2Mn2+4Fe2+[Si2B8O24], a new mineral from Momeik, Myanmar,” European Journal of Mineralogy, Vol. 27, No. 6, pp. 793–803). It was named after Swiss gemologist Adolf Peretti, head of the GemResearch Swisslab, who found the first specimens.
Perettiite-(Y) has a very unusual composition, Y2Mn4Fe[Si2B8O24]. It forms strongly tapered yellow needles up to several millimeters long; only very rarely do they form beautiful bundles (figure 1, left). Several other inclusions were also found in phenakite from the same locality, including the very rare tin borate tusionite, which forms groups of mica-like yellow plates (figure 1, right). Phenakite itself is also unusual, because it often forms twins with very strange “drill bit” termination (figure 2). Unfortunately, perettiite-(Y) and tusionite inclusions (figure 3) are extremely rare, found in just a few pieces in a thousand phenakite crystals, so cut stones will remain a valuable collector’s rarity (figure 3).

Figure 2. Phenakite twin, measuring 1.35 cm high, with a “drill bit” termination and perettiite-(Y) inclusions. Photo by J. Hyršl. From the author’s collection.

Figure 3. Phenakite with tusionite (left) and perettiite-(Y) inclusions (right). The specimen on the left weighs 1.77 ct, and the one on the right weighs 2.31 ct. Photo by J. Hyršl. From the author’s collection. @chapter:5


Publication Year: 2022 Title: Yellow Topaz from Germany, Emerald Mining in Austria’s Habachtal Region, a Return to Tucson, and More… Abstract: Welcome to the Spring 2022 issue of Gems & Gemology! For our industry, February is marked by the Tucson gem shows, and we’re delighted to share content from our highly anticipated return to Tucson. With our two feature articles, our regular columns, the debut of a new regular feature, and the annual G&G Challenge, there’s something for everyone in this issue.
In our lead article, Manuela Zeug and coauthors explore yellow topaz from the Schneckenstein crag in Saxony, Germany. The article provides a comprehensive summary of mineral, chemical, and spectroscopic investigations of Schneckenstein topaz, with an emphasis on luminescence studied by excitation-emission spectroscopy. This study offers a new perspective on previous mineralogical studies, which focused mainly on crystal forms and trace element geochemistry.
Our second feature article revisits the history of emerald mining in Austria’s Habachtal region. In the second installment of his two-part series, Karl Schmetzer traces the history of the Habachtal mine during the era between World Wars I and II, using a variety of largely unpublished sources from Austrian and German archives.
“We’re delighted to share content from our highly anticipated return to Tucson.”
Our regular features have much to offer, too. Among the variety of snapshots in Lab Notes, we report on two notable laboratory-grown diamonds recently examined by GIA: a new record-size CVD diamond and one with unusual laser drill holes. Micro-World offers a glimpse into the inner landscapes of gemstones, including a before-and-after comparison of an oiled apatite cabochon, a complex fluid inclusion in topaz, and a garnet crystal inclusion in aquamarine. Our Gem News International section features more than 30 pages of coverage from the 2022 Tucson shows, with market updates, interesting and noteworthy finds, and interviews with dealers, cutters, and designers. Other highlights from Gem News International include a study of irradiation treatment in amber and the discovery of davemaoite in a diamond from the earth’s lower mantle.
This issue also includes the debut of an exciting new section: Diamond Reflections. In his first installment, Evan M. Smith explores the potential role of modern-day deep-focus earthquakes on diamond growth.
Also in this issue: Be sure to take the annual G&G Challenge quiz, which offers the chance to test your gemological knowledge of our feature articles from 2021. And we congratulate the winners of this year’s Dr. Edward J. Gübelin Most Valuable Article Award.
We hope you enjoy the Spring edition of Gems & Gemology! @chapter:29


Publication Year: 1990 Title: Summer 1990 G&G Lab Notes Abstract: Cultured Calcareous Concretions
Imitation Coral
Etch Channels in Diamond
Purple Diamond
Radioactive Glass Egg
Banded Lapis Lazuli
Gray Baroque Cultured Pearl
“Well-Worked" Pearl
Unusual Gem-Quality Sodalite
Spinel from Tanzania
Synthetics and Simulants in Period Jewelry

To view the full section, download the PDF above. @chapter:17


Publication Year: 2002 Title: Gemesis Laboratory-Created Diamonds Abstract: High-quality yellow, orange-yellow, and yellow-orange laboratory-created type Ib diamond crystals up to 3.5 ct are being produced commercially by the Gemesis Corp. of Sarasota, Florida. In some samples, color zoning (yellow and narrower colorless zones) and a weak UV fluorescence pattern (a small green cross-shaped zone combined with an overall weak orange luminescence) provide means of identification; when present, metallic inclusions also indicate laboratory growth. Some samples lack these diagnostic visual features, but all of these Gemesis synthetic diamonds can be identified by advanced instrumentation such as the De Beers DiamondView luminescence imaging system and EDXRF chemical analysis. @chapter:11


Publication Year: 2016 Title: Book Review: If These Jewels Could Talk: The Legends Behind Celebrity Gems Abstract: By Beth Bernstein, 254 pp., hardcover, illus., publ. by Antique Collectors Club, Woodbridge, Suffolk, UK, 2015, US$95.00.

	Beth Bernstein’s If These Jewels Could Talk is a lush visual treat for anyone interested in the history of cinema, important jewelry and gemstones, and the place of powerful women in Western culture. The timeless jewelry pieces, by some of the biggest names in the jewelry industry, almost outshine the celebrities who owned and wore them.

	While the book showcases some spectacular jewelry owned by wealthy socialites (Barbara Hutton), women close to royalty (Wallis Simpson), and actual royalty (England’s Queen Elizabeth and Princess Diana), the primary focus is on pieces worn and treasured by Hollywood’s leading ladies. Although Bernstein touches on the actresses of today, they are overwhelmed by the tribute she pays to the iconic films of the 1930s, ’40s, and ’50s that starred women who are still synonymous with glamour: Mae West, Carole Lombard, Merle Oberon, Grace Kelly, Elizabeth Taylor, and Audrey Hepburn. This book belongs to them.

	With such an eclectic mix of jewelry and stars, organization might present a challenge, but Bernstein has logically divided the book into 14 chapters. The first five are organized by gemstone: Sapphire Sirens, Emerald Enchantresses, Ruby Romantics, Diamond Divas (with a subheading “Diamonds Are Forever,” featuring engagement diamonds), and Pearl Girls. A surprise from the sapphire chapter was the popularity of enormous star sapphires in the 1930s and ’40s).

		Sentimental Journeys (jewelry given as wedding or love gifts, and charm bracelets)

		Real to Reel (jewelry used in films and created for films)

		Screen to Street (pieces featured in films that created a demand in the market place)

		Owning It (jewelry owned by actresses and worn by them in numerous films)

		Building Character (jewelry that played a significant part in films, such as the ruby and diamond necklace worn by Julia Roberts in Pretty Woman, or Audrey Hepburn’s diamonds in Roman Holiday)

		Time Keepers (wrist watches in film)

		Credits Roll (the role jewelry houses played in supplying pieces for film and the reciprocal impact of those pieces on the houses’ reputations)

		Powerful Passionates (pieces purchased and commissioned by the women themselves)

		Bring On the Brands (capsule histories of some of the biggest jewelry houses in the world)

	The stories are delightful, romantic, and occasionally sad: Mike Todd’s surprise recreation, in diamonds, of Taylor’s paste earrings; Mae West’s husband’s refusal to sell her jewelry after her death, despite his own financial need; Edward VII’s presentation to Wallis Simpson of cross charms marking significant points in their courtship.

If These Jewels Could Talk is somewhat marred by poor sentence construction and muddy wording that confuses and distracts the reader. (Referring to the Duchess of Windsor’s panther clip brooch, for example: “This classic Cartier sapphire is set in white gold and platinum with single-cut white diamonds. It has yellow pear-shaped diamond eyes with smaller sapphire cabochons for the feline’s spots.”) Such flaws could have been eliminated by a careful final edit.

	In reality, the text is secondary to the photos of brilliantly designed jewelry, such as Merle Oberon’s breathtaking emerald and diamond necklace, the hand jewelry designed for the 2013 big-screen version of The Great Gatsby, and just about anything that belonged to Elizabeth Taylor. The glamour shots of actresses wearing their pieces are captivating. (A personal favorite is the image of Carole Lombard with a magnificent star sapphire clipped to a hat. The star is sharply lit and brilliant—even in black and white.) Also contributing to the visual feast are the drawings produced by the jewelry houses of jewels such as the neckpiece that would eventually showcase Taylor’s La Peregrina pearl.

	More than anything, this book is a reminder that jewelry bespeaks power and always has. And these women had real power: sexual power to inveigle men to buy important jewelry for them, power to influence market demand and fashion trends, financial power to purchase their own jewelry, and (in the case of Wallis Simpson) political power.

	For this alone, this unforgettable image of women of power, this large-format, high-quality coffee-table book is highly recommended. @chapter:16


Publication Year: 2019 Title: Cobalt-Coated Sapphire Abstract: Figure 1. Lighter facet junctions and a speckled surface are evidence of coating. Photomicrograph by Tyler Smith; field of view 4.79 mm.

Recently, the New York laboratory received a bright blue stone for identification. The blue color closely resembled that of the highly desired cobalt spinel. Advanced testing procedures of Fourier-transform infrared (FTIR), ultraviolet/visible/near-infrared (UV-Vis-NIR), energy-dispersive X-ray fluorescence (EDXRF), and laser Raman spectroscopy were performed to aid in identification. FTIR revealed a corundum spectrum, but with an uncharacteristic rise in the 7000–5800 cm–1 region. Laser Raman spectroscopy confirmed corundum, and UV-Vis-NIR yielded a cobalt absorption spectrum similar to that of diffused cobalt spinel.
Magnification revealed the presence of a coating, which was responsible for the observed over-the-limits RI reading. The coating was easily detected by the speckled, uneven surface and lighter facet edges where the coating was damaged (figure 1). EDXRF identified the coating as cobalt, consistent with the UV-Vis-NIR absorption spectrum. The stone possessed typical heated sapphire inclusions, such as altered fingerprints and frosted crystals. In addition, Raman spectroscopy identified glass-filled surface-reaching cavities (figure 2).

Figure 2. Glass-filled cavities on the sapphire’s pavilion. Photomicrograph by Tyler Smith; field of view 3.57 mm.
Cobalt coating is already a known treatment of tanzanite to improve the blue color component, but GIA has not observed cobalt coating on sapphire in recent years (see Spring 1994 G&G, pp. 48–49). Unlike cobalt coating on tanzanite, which has been observed applied only to the pavilion, this coating covered the entirety of the sapphire. This highlights the possibility of cobalt coating on materials other than tanzanite to induce a more pronounced blue color.
Because of its color, this material is most likely to be mistaken for cobalt spinel, which can easily be eliminated as a possibility through standard gemological testing with the polariscope and specific gravity. The stone tested was doubly refractive and had a specific gravity of 4.00, while spinel is singly refractive and has an SG of 3.60 (+0.10/–0.03). Although the RI was over the limit of the refractive index liquid, the stone’s specific gravity and doubly refractive nature point to sapphire. Advanced testing was useful in confirming the true identity of the stone and the coating. @chapter:12


Publication Year: - Title: Making Connections in 2019: Alumni Association India-Themed Event, Buccellati Contest Winner, and Other GIA Activities in Tucson Abstract: From left: Robert Gessner, Maryanna Nagle, Jennifer Pusenkoff and Melissa Gessner.

More than 350 alumni and guests from 16 countries gathered for the 2019 Party at the GIA Gem Mine in Tucson recently to re-connect with former classmates, meet new industry friends, and perhaps even establish a new business relationship.
This year’s theme, “India-Odyssey,” paid tribute to the great diversity and beauty of India. The country’s dichotomy of extravagance and simplicity as seen in its colorful textiles, geography and cultures has influenced and changed the course of history, particularly in the jewelry industry. Many legendary gems have been unearthed in India and for centuries master craftsmen have fashioned magnificent jewelry from them. India has made priceless contributions to the advancement, appreciation and desire to own gemstones and jewelry across the globe.

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Party-goers were able to pose with Indian-themed props at the photo booth and get “Golconda Glam” with a temporary tattoo.
The event was also an opportunity to display the 18 original design renderings of the finalists of the second annual Gianmaria Buccellati Foundation Award for Excellence in Jewelry Design. The competition – open to students who successfully completed the GIA Jewelry Design course in 2018 – recognizes artistic excellence in jewelry design. Hand-rendered designs from 18 finalists from seven GIA schools were judged by a committee comprised of known gem and jewelry industry experts in design, manufacturing and jewelry retail experts.

Ching-Hui Weng’ design of “Urocissa caerulea,” a blue bird that represents Taiwan, won the 2018 Gianmaria Buccellati Foundation Award for Excellence in Jewelry Design. GIA digital file
Susan Jacques, president and CEO of GIA, announced that Ching-Hui Weng, who studied at GIA’s Taiwan school and received her GIA Jewelry Design certificate in 2018, was the winner. Her design rendering of “Urocissa caerulea,” a blue bird that represents Taiwan, was comprised of a yellow and white gold brooch featuring opals, aquamarine, lapis lazuli, black chalcedony, coral, and white and yellow diamonds.
“My source of inspiration is the flight dynamics of these birds, used in combination with gemstones to express their flight,” Weng said.

GIA Governor Barbara Dutrow bids on an item during the silent auction.
Jacques then kicked off the always exciting and competitive live auction led by GIA alumni Lindy Adducci of DuMouchelle Auctions, who volunteers her professional services each year. All proceeds from the event support the Alumni Endowment Fund. This year’s event raised nearly $30,000 from event tickets and the silent and live auctions. More than 75 items, including loose gemstones and pearls, designer jewelry, mineral specimen, equipment, books and more were available to bid on.
“This annual reunion of alumni and industry friends continues to impress in both its dynamism and attendance, and we excited to bring together so many of diverse members of the trade together for this evening of networking and fun, while supporting the Alumni Endowment and giving ultimately give back to our constituency,” said Kate Donovan, manager of global alumni relations. “This event takes a village to execute and I would like to extend a special thank you to all of our auction contributors, supporters, event attendees and volunteers.
“We look forward to seeing you all again and encourage you to mark your calendar on Friday, Feb. 7, 2020 for next year’s party.”

Amanda Hornberger and Laura Hornberger.
Alumni Leadership Breakfast
GIA Alumni Association chapter leaders and senior GIA executives also gathered in Tucson for a breakfast meeting that included interactive dialog between alumni volunteer ambassadors and GIA executives who presented and shared GIA’s commitment to support alumni worldwide with programs and expanded benefits.
More than 40 leaders from 19 chapters attended, including representatives from Asia, Canada, Europe, Mexico, and the U.S. were present, along with GIA executives Susan Jacques, president and chief executive officer; Duncan Pay, vice-president and chief academic officer, Robert Weldon, director of the Richard T. Liddicoat Gemological Library and Information Center, Susan Schindelar, vice president of global marketing and Stephen Morisseau, director of corporate communications.
Kate Donovan, manager of global alumni relations, led the gathering by welcoming attendees and recognizing the volunteer efforts of the global alumni leaders (as individuals and as chapters) for their extraordinary efforts and accomplishments that helped the GIA Alumni Association achieve a banner year in 2018. Looking ahead, she introduced the newly expanded alumni department team members, and shared GIA’s executive commitment to support the Alumni Association and some recent and planned actions to further this support.
Jacques and Pay shared the initiatives under way to strengthen and expand support for all alumni members and chapters worldwide by providing relevant resources. An update was provided on GIA services, education initiatives and the Institute’s commitment to expanded gemological research and how these initiatives support the entire lifetime of our constituency, from student through time as an alumnus and industry veteran. Jacques also urged the group to actively reach out to new alumni and invite them to participate in local chapter activities.
The event wrapped with an open forum discussion and between chapter leaders and GIA’s alumni and executive representatives. They shared best practices and experiences from their chapters, and exchanged ideas, challenges and requests on how to improve support to chapters and leadership volunteers so they can serve the GIA Alumni Association community in the year ahead.

Composite image of jumbo gemstones for TGMS Tucson 2019. Left, clockwise: 11905 ametrine, 368 ct, Minas Gerais, Brazil, gift of Dr. L. T. Moore. 684 yellow topaz, 1002 ct, Brazil, gift of Dr. Gerald T. Zwiren. 24606 sherry pink fluorite, 311.55 ct, gift of Donald and Ruth Milliken.  5901 yellow spodumene, 200 ct, Afghanistan, gift of Daniel J. and M. H. Henkin. 1958 green beryl, 156 ct, Brazil, gift of Mr. and Mrs. Vicaro Jay Martin. 14716 pink morganite, 292 ct, gift of Dr. William L. Harville Jr. 36817 yellow beryl (heliodor), 226 ct, Brazil. See related asset. Orasa Weldon/GIA
GIA Museum and Library Exhibits
The GIA Museum presented a display of “Jumbo Gems” – the largest, a 21,290 ct rock crystal quartz from Brazil – to demonstrate the importance of facets and how they play a role in bringing beauty to a gemstone, as well as the size in which some gem materials can occur.
The GIA library presented “Selecting Gem Rough: A Guide for Artisanal Miners,” an educational guide created by GIA that contains basic gemological concepts to help artisanal miners in Africa better understand value factors in the rough they mine. Results have shown that miners have tripled the value of their production. The exhibit case included rough and cut examples of many East African gems including amethyst, aquamarine, diamond, emerald, garnet, opal, sapphire, tanzanite, tourmaline and zircon.

A miner in Tunduru, Tanzania examines the artisanal mining guide following GIA’s lecture on the subject. Photo by Robert Weldon/GIA
Robert Weldon, director of the Richard T. Liddicoat Gemological Library and Information Center and co-author of the guide, detailed the story behind the guide and how it benefitted approximately 1,000 gem miners in Tanzania, especially the women. @chapter:36


Publication Year: 2022 Title: Eye Pattern in a Rock Fragment Abstract: An eye pattern complete with pupil, iris, and sclera is clearly visible in this rock fragment. Photomicrograph by Polthep Sukpanish; field of view 12.5 mm.
Recently, the authors encountered a partially polished rock fragment measuring 14.50 × 9.43 × 2.43 mm and weighing 3.45 ct that exhibited a very realistic eye pattern (see above). Various shades of yellow and green material formed the pupil and iris, while a distinctive white outline surrounded the iris as a sclera. Microscopic observation revealed different microcrystalline minerals. Raman spectroscopy identified pyroxene, feldspar, and quartz as the most abundant minerals. Energy-dispersive X-ray fluorescence (EDXRF) analysis revealed silicon as the dominant element, while traces of iron and potassium were also detected.
Naturally formed eye patterns in gems are rare but do exist, such as a “dragon’s eye” in a fire agate (Winter 2015 G&G Micro-World, p. 441) and a radial eye structure in a sapphire (Summer 2017 G&G Micro-World, pp. 244–245). While the textures in rocks are much more diverse than those in single-mineral gemstones, observing such a unique feature is always exciting. @chapter:10


Publication Year: - Title: Colorblocking: The Art and Fashion of Multicolor Gemstones Abstract: The complex faceting of this ametrine creates a blended effect of purple and yellow, reminiscent of a Bolivian sunset. Courtesy of Minerales y Metales del Oriente, Bolivia, SA. Photo by Robert Weldon/GIA

Clothes, handbags, shoes and accessories that sport multiple solid colors, usually in bold and bright shades called colorblocking, have reappeared on the fashion scene in a big way the last few years, but the trend is not new. It first appeared in Yves Saint Laurent’s 1965 collection, which was inspired by the artistic styles of modern Dutch artist Piet Mondrian, whose paintings were a collection of geometrical and colorful shapes. This 1960s mod fashion may be passé, but just as trends in fashion often return and thrive again, colorblocking feels new.

In the gem world, this style is found in the artistic combinations of color in multicolor gemstones appreciated for their color zoning or banding. Color banding in gems occurs in shapes or distinct layering. Agate, for instance, often forms in geometric shapes, while tourmaline and fluorite form in bold lines and stripes.

This Padparadscha sapphire shows color zoning of orange to pink to orange again. Courtesy of Mayer & Watt, Maysville. Kentucky. Photo by Robert Weldon/GIA
Agate and quartz crystallize in zones when chemical or physical conditions change during their formation. When iron is present during the formation of quartz, it can produce citrine, amethyst or ametrine. As the name suggests, this gem is a combination created by color blocks of amethyst and citrine. Depending on how the color zones are oriented during cutting, the two blocks of color (yellow and purple) can be emphasized.

Alternately, these colors can be merged through cutting to produce rich, purple hues of amethyst with honey-color citrine. The result is a striking gem that evokes romantic Bolivian sunsets. The Anahí mine in eastern Bolivia is the only commercial source of ametrine, one of the most exotic multicolor gemstones. Bolivia claims it as its national gemstone.

Copper is the trace mineral that produces the turquoise color in this tourmaline, colorblocking the complimentary colors. Courtesy of Mayer and Watt, Maysville, Kentucky. Photo by Robert Weldon/GIA
Tourmaline, more than any other gemstone, is found in every hue and it often has two or more colors visible in a single specimen. The chemical variations during tourmaline’s crystallization determine its color. Multicolor tourmaline can form in zones resembling blocks of color as in bicolor tourmaline – in a great number of color combinations. Black or brown tourmalines get their color from iron. Brown to yellow tourmalines are colored by magnesium. Lithium produces tourmalines that are blue, green, red, yellow or pink.

Tourmaline derives its name from the words “tura mali" loosely translated to "stone of mixed colors" in the Sinhalese language of Sri Lanka. Ancient Egyptian legend tells us that tourmaline passed over a rainbow on its long journey from the center of the earth and took on the spectral colors.

Liddicoatite is a calcium-rich lithium tourmaline named in honor of Richard T. Liddicoat in recognition of his more than 60 years of service to the gem and jewelry industry. Beautiful zones and bands in liddicoatite form in bold colorful patterns due to the changing mix of elements. Colorful slices of liddicoatite are often concentric bands of pink to red, green, blue and light brown.

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Fluorite also occurs in every color of the spectrum and is a favorite multicolor gemstone. It is popular with collectors because of its bold colors. Its cubic crystal growth results in a variety of crystal shapes. The word "fluorescent" is derived from the mineral fluorite since many specimens fluoresce strongly, exhibiting a prismatic color variation when viewed in ultraviolet light. The softness of fluorite (4 on the Mohs hardness scale), suggest it is best be carved into ornamental objects. Rarely faceted, cut fluorite is a collector’s prize, especially when it shows great variety of colors in one gem.

The colorblocking trend in fashion may be a recurrent theme, but the popularity of multicolor gemstones exhibiting a similar effect is enduring. @chapter:26


Publication Year: 2017 Title: Elements in Synthetic Overgrowth on Flux-Heated Ruby and Beryllium-Diffused Sapphire Abstract: Figure 1. Synthetic overgrowth on the surface of a heated Burmese ruby. Photo by Yusuke Katsurada; field of view 1.50 mm.

Heat treatment of rubies and sapphires at high temperatures sometimes leaves redeposition caused by the partial dissolution of the corundum in the crucible; this is referred to as synthetic overgrowth (Fall 2002 GNI, pp. 255–256). GIA’s Tokyo laboratory recently had the opportunity to test a red oval mixed cut weighing 2.00 ct and an orange round mixed cut weighing 0.89 ct, both of which showed signs of synthetic overgrowth after testing.

Standard gemological testing and advanced testing including chemical analyses revealed that the red oval was a heated ruby of Burmese origin with moderate flux residues in fissures. The orange round was identified as a beryllium-diffused sapphire. Both stones had synthetic overgrowth around the girdles and/or cavities (figures 1 and 2) that could be confirmed by different reactions under cross-polarized light. We tested the overgrowths with laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) with calibration using NIST 612 and 610 standards.

Figure 2. Synthetic overgrowth on an orange beryllium-diffused sapphire. Photo by
Yusuke Katsurada; field of view 1.60 mm.
The chemical compositions of these synthetic overgrowths were different from those of corundum; they also varied between the samples. Sodium (9980 ppmw), calcium (40,100 ppmw), magnesium (84,400 ppmw), and silicon (23,400 ppmw) were extremely high in the overgrowth on the flux-heated ruby; beryllium (36,650 ppmw) was extremely high and silicon (909 ppmw) very high in the overgrowth on the beryllium-diffused sapphire (table 1). Boron was detected only in the overgrowth on ruby (59 ppmw). Aluminum was not quantified since it was used as an internal standard. However, the high aluminum signal indicated that the overgrowth contained corundum and/or alumina-related material.

TABLE 1. Elements in heated ruby and Be-diffused sapphire and their synthetic overgrowths detected by LA-ICP-MS (avg. concentration in ppmwa).

Heated ruby
Be-diffused sapphire

Element
Stone
Overgrowth
Stone
Overgrowth

Be
bdlb
5.00
8.86
36,650c

B
bdl
59.0
bdl
bdl

Na
bdl
bdl
10.6
10.6

Mg
10.5
61.1
328
328

Si
bdl
bdl
909
909

K
bdl
1790
bdl
bdl

Ca
bdl
40,100
bdl
bdl

Ni
bdl
104
0.42
6.20

Cu
1.71
50.1
bdl
8.34

Zn
bdl
64.0
bdl
12.7

Zr
0.04
27.6
bdl
296

Pb
bdl
93.7
bdl
0.15

a All detection limits are below 4 ppmw except for Si (heated ruby: 113.5 for stone, 104.1 for overgrowth; Be-diffused sapphire: 93.3 for stone, 80.0 for overgrowth) and Ca (heated ruby: 16.95 for stone, 15.79 for overgrowth; Be-diffused sapphire: 16.95 for stone, 15.79 for overgrowth).
b bdl: below detection limit
c These values were linearly extrapolated with pulse-analog linear dynamic range measurement of the instrument.

Flux is used for artificial heat treatment of rubies, and there are many types of fluxes such as oxides, borates, silicates, molybdates, and fluorides, as well as various combinations of materials (J.L. Emmett, “Fluxes and the heat treatment of ruby and sapphire,” Fall 1999 G&G, pp. 90–92). During flux-assisted heat treatment with or without diffusion, material from the surface of the corundum as well as the alumina crucible and inclusions will dissolve to some degree into the molten flux. On cooling, the flux becomes supersaturated in alumina and crystallizes out onto the nearest convenient surface, often on the stones themselves (J.L. Emmett et al., “Beryllium diffusion of ruby and sapphire,” Summer 2003 G&G, pp. 84–135). Uncommon elements for corundum such as sodium, calcium, and silicon obtained from the overgrowth on heated ruby in high concentration indicate that the overgrowth was mainly derived from fluxes. These elements are comparatively insignificant for the overgrowth on beryllium-diffused sapphire. On the contrary, extraordinarily high beryllium in the overgrowth on Be-diffused sapphire indicates deposition of this additional element in the treatment. Other elements, such as magnesium and zirconium (detected at moderate to high levels), and metals such as nickel, copper, zinc, and lead (detected from both overgrowths at lower levels) may be from the inclusions or the flux.

LA-ICP-MS results (table 1) also indicate that the ruby could be misidentified as Be-diffused since the overgrowth contains a certain amount of beryllium, a possible by-product of the furnace. It is important for gemologists to check other elements such as magnesium, silicon, and calcium in order to confirm that LA-ICP-MS was performed on the overgrowth. @chapter:12


Publication Year: 2023 Title: The history of gemstones in Chanthaburi_27 Abstract: The peak of the gemstone industry in Chanthaburi province, I believe, was around the period of Siamese rubies, approximately between 2520 and 2535 (1977-1992), before the Asian financial crisis occurred. @chapter:25


Publication Year: 2022 Title: Yellow Sapphires with Unstable Color Abstract: Figure 1. Left: Before a fade test, this approximately 10 ct sapphire displayed a strong orange hue. Right: After the fade test, the orange color became less pronounced and the stone appeared yellow. Photos by Ronnakorn Manorotkul.
In recent years, one concern our laboratory has heard from clients and from other gemologists is the issue of color stability in corundum. Some sapphires, particularly those with a strong yellow component (including padparadscha sapphire), contain unstable color centers that may fade when the stone is exposed to light and/or heat (K. Nassau and G.K. Valente, “The seven types of yellow sapphire and their stability to light,” Winter 1987 G&G, pp. 222–231). We regularly test for this in the laboratory by conducting a fade test. Most of the sapphires we encounter that have an unstable color are unheated stones.

Figure 2. A cluster of glassy discoids suggests that this sapphire has been heat treated. Photomicrograph by E. Billie Hughes; field of view 4.0 mm.

Figure 3. This small crystal with a melted appearance provides evidence that the specimen has undergone heat treatment. Photomicrograph by E. Billie Hughes; field of view 3.5 mm.
Recently an orange sapphire of approximately 10 ct was submitted for testing (figure 1). Microscopic examination revealed signs of heat treatment, with partially dissolved silk, several glassy discoids (figure 2), and melted crystals (figure 3). A fade test was conducted by placing the stone approximately 5 cm under a 120-watt incandescent spotlight for at least an hour, and a dramatic difference was observed. The color had changed from orange to a vivid yellow (again, see figure 1).
Under normal conditions, high-temperature heat treatment (at least 1200–1300°C) will bleach any color centers that might be present. This suggests that the orange color was activated after the heat treatment. It is possible that this occurred either by subjecting the stone to artificial irradiation or by placing it in sunlight (Nassau and Valente, 1987). However, we are unable to state definitively what process was used to activate the orange color.

Figure 4. Before a fade test, the unheated sapphire of approximately 18 ct displayed a highly saturated yellow hue (left). After a fade test involving light and mild heat, the color faded to a pale yellow (right). Once the stone was exposed to sunlight for 30 minutes, the more intense yellow color displayed before the fade test came back. The sapphire was then subjected to a light-only fade test, and the more saturated yellow color remained stable. Photos by Ronnakorn Manorotkul.
Several weeks later, we tested another yellow sapphire of approximately 18 ct (figure 4). In this instance, the stone’s features were consistent with those of unheated sapphire. Again, a fade test was performed with the 120-watt spotlight, which mildly warmed the stone to approximately 100°C. Its color also faded after the fade test, and the owner was informed. The owner explained that they had previously put the sapphire in direct sunlight, which would have brought the color back to what was likely its stable state, a process described by Nassau.
To test this, we placed the stone in direct sunlight for 30 minutes, and the more intense yellow color did return. Unfortunately, placing the gem in direct sunlight behind a window in our office did not have the same effect.
Upon seeing the color return after being placed in direct sunlight, we decided to try another fade test, this time using a light source that would not warm up the stone. An XD-300 xenon light source was used, and the stone was placed within 5 cm of a fiber-optic light guide connected to this source. After exposure to this cooler light source for over an hour, the color did not fade. This suggests that the mild heat of the 120-watt spotlight, not just the light, faded the stone’s color and that the more intense yellow color displayed after exposure to sunlight could indeed be considered the stable color.
We have since adjusted our fade tests to be light-only by switching to this cooler light source to avoid the heat generated with the 120-watt spotlight.
Our experience with these sapphires has been a fascinating case study in the color stability of yellow sapphire. This example reinforces the importance of considering all possibilities when testing stones in the laboratory. We do not fully understand the exact causes of these changes, and much remains to be learned. @chapter:12


Publication Year: 1986 Title: An Examination of Four Important Gems Abstract: The authors report on their gemological examinations of four important gemstones: the Star of Bombay sapphire, the Portuguese diamond, and two large diamonds known as the Marie Antoinette earrings, all of which are part of the collection at the Smithsonian Institution. Brief historical information on some of the pieces is also included. @chapter:20


Publication Year: 2007 Title: Continuity and Change in Chinese Freshwater Pearl Culture Abstract: The great majority of Chinese freshwater cultured pearls are produced by implanting tissue pieces in the mantle of Hyriopsis cumingii mussels. Farmers have experimented with bead nucleation, but until recently the methods tried did not produce the quantity or quality necessary for economic success. In the late 1990s, Chinese researchers imported H. schlegelii mussels from Japan, began propagating them in hatcheries, and started cross-breeding them with native H. cumingii mussels. Using the two pure species and the hybrid, Chinese farmers produce tissue implantation-only cultured pearls and have developed a method called coin-bead/spherical-bead nucleation. This method has yielded significant quantities of jewelry-quality baroque shapes and lesser quantities of jewelry-quality rounds and near-rounds. Continued experimentation is expected to increase the percentage of rounds and near-rounds. @chapter:14


Publication Year: 1988 Title: Fall 1988 G&G Lab Notes Abstract: Unusual Inclusions in a Synthetic Alexandrite
Dyed Spangled Amber
Chinese "Onyx" Augite
Calcareous Concretion
Treated Green Diamonds
Assembled Ironstone Opal
Opaline "Rock"
South Seas Cultured Pearl
Flux at the Surface of a Synthetic Ruby
Sagenitic Stones
Abraded Sapphire
Synthetic Brown Star Sapphire
Taaffeite with Unusual Fluorescence
Triphylite

To view the full section, download the PDF above. @chapter:17


Publication Year: 2023 Title: Night Sky in Yellow Sapphire Abstract: This scene of an iron stain and numerous curved lines showing rainbow colors in a fracture resembles a scene from the night sky viewed through a telescope rather than a microscope. Photomicrograph by Charuwan Khowpong; field of view 2.85 mm.
Fractures are usually not desired in gemstones, but in some cases they provide a great subject for photomicrography. When a 2.49 ct yellow sapphire from Ilakaka, Madagascar, was examined with a fiber-optic light, the scene in the figure above was revealed. It is reminiscent of a long-exposure photograph of a star-filled sky with an extraterrestrial object floating in it. In reality, this is a globular iron stain in a large fracture, but the spotted iron staining evokes a faraway planet. The colorful curved lines are conchoidal patterns in the fracture. The combination of features makes the image seem as if viewed through a telescope rather than a microscope.
Illumination is very important for capturing the iridescence effect. Only if a strong fiber-optic light is used at the correct angle relative to the fracture will the colorful curved lines be highlighted. @chapter:12


Publication Year: - Title: First Look at 2014 Season: Uneven Demand Abstract: The world is watching the U.S. retail market as the economy rebounds and the U.S. dollar gets stronger. Photo by GIA

                      Diamond and jewelry demand in the U.S. rose an estimated 3% to 4% this past holiday season, but business was uneven.

Upscale jewelers did well in general, but large chain stores reported slower than expected sales. Business at high-end, well-established independents was strong, according to a Centurion survey. Ninety percent of the stores surveyed reported that sales were up for the year, with nearly half noting increases of 10% or more. For the season, 41% saw double digit increases, while another 20.6% found business up between 6% and 10%. Nearly 11% reported that sales were down for Christmas.

Anecdotally, business among middle market retailers seemed mixed, with many reporting down-trading in quality and a lot of demand shifting to silver and bead-type merchandise.

Among the chains that reported, Tiffany & Co.’s U.S. same store sales declined by 1%. The company’s European operations saw a 4% increase in same store sales (most likely from an increase in Asian tourists, because the local economies are not doing well), while Japan plunged 8% (13% in Yen terms). Sales in China and Singapore increased 7%.

Tiffany chairman Michael Kowalski called the results “disappointing” in a press release and noted that the rising U.S. dollar will cause “headwinds” for the company’s international business.

Signet Group/Zales was the first major retail jeweler to post seasonal figures, noting that same-store seasonal U.S. sales were up 2.5%, about half of the previous years’ growth. Zales, acquired by Sterling in 2014, posted a 3.5% increase in same store sales, which had been treading water for some years before the acquisition. Reading the statement, it appears that Zales’ holiday business was buoyed significantly through expanding its online channels. Signet Group/Zales noted that its combined ecommerce sales increased 90% for the season, but only by 20% when excluding the Zales division.

In China, business is reported very cautious heading into the Chinese New Year, when many workers receive substantial bonuses. Retail inventories of diamonds and gold jewelry remain high, while sales, though increasing, have continued to taper off from the heady growth years.

Chow Tai Fook reported that its same store sales fell 18% compared to the final quarter of 2013, and gem-set jewelry sales fell 12%. While the declines were most pronounced in Hong Kong and Macau, the company noted that high-end jewelry sales were weak overall. The company also noted that comparisons with 2013 were “difficult” because that year was marked by a rush for gold products after the metal price crashed.

Diamond demand was apparently not sufficient enough this past holiday season to cause a restocking rush that would enable the world’s diamond industry to escape the profit and credit squeeze that plagued it last year. Polished prices continue to soften while rough remains expensive.

Accordingly, De Beers will reportedly reinstate the provision to allow its sight clients to defer purchase of up to 25% of their allocations. In addition, the Jan. 19-23 sight may see small price reductions (De Beers calls them “adjustments”) for categories of rough diamonds.

Prices at De Beers’ sights, which still comprise the single largest source of rough diamonds, have not declined. And Alrosa, which produces about one-third of the world’s diamonds by volume, is under severe pressure to raise prices after the collapse of the rouble and the extremely significant loss in oil revenues for Russia’s treasury.

Because their own costs are rising, producers have resisted reducing prices that have left diamond manufacturers in an extreme profit squeeze at a time when the leading industry banks have severely cut their credit facilities. This has been well-reported for more than a year and the situation shows no sign of improving in 2015.

De Beers CEO Philippe Mellier, addressing U.S. jewelers in New York last week, said the rough/polished price squeeze will improve when polished and rough supplies move into balance.

Moving into 2015, much of the diamond and gemstone world will refocus on the U.S. market because of the gathering economic rebound, and the strengthening U.S. dollar, which raises the cost of most gemstones (except cultured pearls and jade) in other markets.

Goods priced in dollars will grow more expensive outside the U.S. (Hong Kong and China base their currencies, in part, on the dollar, so they fluctuate less), but the Euro and Yen have lost 20% in value, thus raising prices for diamonds and gold by that much in those markets. In addition, the high U.S. dollar may attract more overseas gemstone sellers to the Tucson shows as U.S. buying power grows. @chapter:27


Publication Year: 2013 Title: EOSFancy: Automatic Bruting of Fancy Shapes Abstract: More than eight years ago, Belgium’s Scientific Research Centre for Diamonds (WTCOD) developed an automatic bruter for round diamonds. The bruting machine was based on a new principle: the application of a grinding wheel, rotating in a cooling liquid, to a rotating diamond. WTCOD has now expanded the scope of the EOS bruting machine to fancy shapes by linking the feed movement of the disc to the rotating position of the diamond. With EOSFancy, one can brute any convex shape with high accuracy and symmetry. The new software requires a recent PC with a specific graphics card. EOSFancy can be used manually or via a transfer from a rough scanner. The system can be used for both prebruting and finishing, and it is the ideal complement to laser prebruting. With EOSFancy, a lasered girdle can be finished perpendicular to the table with a result closer to the end dimensions, with a shorter processing time. The development is now in testing phase at a limited number of Antwerp-based diamond companies. A commercial version is expected to be released by HRD during 2013.

Abstracted by Guy Lalous @chapter:31


Publication Year: 1998 Title: Leigha: The Creation of a Three-Dimensional Intarsia Sculpture Abstract: Traditional gem intarsia, essentially flat interlocking mosaic work, is generally restricted to two-dimensional surfaces. Taking intarsia into three dimensions “in the round” requires the use of new techniques. This article illustrates the process of creating a contemporary three-dimensional intarsia sculpture. The skirt in Leigha was executed with over 800 separate pieces that averaged 1 to 2 mm in thickness. As the skirt is over 12 inches (30 cm) long, the necessary tensile strength to hold the pieces together required the use of the relatively new ultraviolet-curing cements, as well as structural design elements that would not be concerns in two-dimensional work. Inspired by an ancient Minoan motif, this intarsia sculpture illustrates some of the expanding possibilities for gem materials in the realm of gemstone objets d’art. @chapter:26


Publication Year: 2015 Title: Books: Michele della Valle: Jewels and Myths Abstract: By Michele della Valle, hardcover, 349 pp., illus., publ. by Antique Collectors’ Club Ltd., Woodbridge, Suffolk, UK, 2014, US$195.00.

	Weighing in at more than eight pounds, this high-quality production is a pictorial autobiography of the Italian-born, Geneva-based jewelry designer Michele della Valle. Claiming to be a poor writer, della Valle presents the story of his creative inspiration and talents through his jewels rather than words. Although these wonders sometimes speak their beauty in hushed tones, they mostly emote, nearly leaping off the page in screaming colors, ebullient with life and joy, yet framed by transcendent balance and class.

	Unlike books that present an artist’s evolution over periods, this tome is loosely organized around individuals, many deceased, who have inspired della Valle’s creativity, ranging from royals and statesmen to writers and Biblical figures, not to mention a Pope (on skis) and a range of artistic talents with opera, ballet, music and celluloid stars particularly represented.

	For example, a sepia-toned full-page photograph of a young Ernest Hemingway alongside a marlin and a fisherman segues to a dramatic blue marlin sapphire, ruby and diamond brooch in carbonium fiber and gold from 2006. An inspirational quote alongside a photograph of President Kennedy in commencement garb introduces a series of red, white, and blue jewelry that stand apart from the tired designs of most patriotic jewelry. The photo gallery closes with opera legend Maria Callas, who trumps other stars with three appearances in the book, in full-color across from the paired carnation brooches she inspired. Even the della Valle pooch ushers in a section of animated animal jewelry that includes a fetching tiger skin bracelet in yellow sapphires and black diamonds.

	Whether themed or not, the magnificent images captured by photographer Laura Camia reveal an artist whose keen sensitivity for nature and glamour also delights in a touch of whimsy. The jeweler’s eye for color is especially striking, from the inviting pastels of the chalcedony and diamond jellyfish earclips (2014) to the multicolored stunning Palette gemstone necklace (1989). Unafraid to enliven varied floral and naturalistic themes through the use of titanium and other new-age metals, the book also features diamond designs using kukui nuts and Bakelite.

	Befitting the exquisite stones chosen, della Valle infuses his high-luxury designs with elegance. However, the roots of his talents and his journey in jewelry remain somewhat obscure. Although offered as his autobiography, della Valle gives readers only three brief paragraphs of text. As quoted in a preface by his partner Rossano Corsano, della Valle describes how he began crafting costume jewelry in his youth. Yet the artist’s later adventures as a gem merchant and his reputed fascination with international glamour are only mentioned in passing. Detailed instead are the activities and livelihoods of della Valle’s mother’s cosmopolitan friends. The man behind the artist remains knowable here only through his jewelry.

	Notwithstanding that, what is on display here, preferably hoisted upon a sturdy coffee table, is a colorful feast bursting with glorious color and infused with graceful energy. Readers interested in jewelry design, high jewelry and connoisseurship will find the book an intriguing, if somewhat ethereal, excursion. @chapter:16


Publication Year: - Title: Lester Benson (1921-1961) Abstract: GIA has long been a breeding ground for people of remarkable talent; one such standout was Lester Benson. Called a “genius” and a “Renaissance man,” Benson made contributions during his 15 years at GIA that changed the future of gemology. His sudden death in 1961 at the age of 39 deeply affected his colleagues and students.

Benson enrolled as a GIA student in 1946, using G.I. Bill benefits he earned during his service in the U.S. Army. He was hired as an instructor by GIA in 1948, after receiving his Graduate Gemologist diploma. While he was a renowned teacher, he distinguished himself in many areas of the field. During his career as a gemologist, he became a master of photomicrography and gem identification. He developed the “spot method,” which allows for the identification of refractive indices of polished gems with curved surfaces. The method is still used by laboratories worldwide. Benson was also a pioneer in the testing realm. Among the techniques he developed are a method for detecting color-enhanced turquoise and an adaptation of the spectrophotometer for gem testing.

In addition to his testing methods and instructional duties, Benson designed many gem instruments, including a pearl-testing X-ray unit, the first Duplex refractometer, and the GIA Jeweler’s Camera. Another of his ideas led to the Diamondlux, a display light for diamonds. His work helped lay the foundations for GIA GEM Instruments. While over 50 years have passed since his tenure at GIA, Benson’s contributions continue to influence the field of gemology. @chapter:29


Publication Year: 1993 Title: Queensland Boulder Opal Abstract: After almost 75 years of inactivity, the deposits of boulder opal in Queensland, Australia, began to attract new interest in the 1960s and 1970s. Queensland boulder opal is found associated with the Winton formation, and results from deposition and dehydration of silica-rich solutions in an iron-rich host rock. At the Cragg mine, one of 69 known opal-mining operations in Queensland in 1991, miners drill as deep as 20 m to search for a deposit and then use open-cut methods to reach the opal-bearing layer identified. In the evaluation of boulder opal, color, pattern, and "composition" are important. Most boulder opal is stable under normal wear, and it is readily separated from its simulants. @chapter:39


Publication Year: - Title: Color Modification of Spinel by Nickel (Ni) Diffusion: A New Treatment in the Gem Market Abstract: Figure 1. Suite of faceted nickel-diffused spinel (0.674–1.009 ct) showing the range of color from blue to bluish green. Photo by Aaron Palke and Diego Sanchez.
In November 2022, a parcel of 24 approximately 0.5–1.2 ct spinel crystals, described as cobalt-diffused, were obtained directly from a treater by the research team at GIA in Bangkok. Of these, seven possessed the deep blue color characteristic of cobalt diffusion, while the others showed lighter blue, greenish blue, bluish green, or blue-green color (figure 1). Slabs were cut from the core of several of these crystals, and all showed diffuse color zonation, from more blue/green at the rims to near-colorless at the cores.
The concentrations of various elements were measured along culet-to-table transects in the slabs using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). The expectation was that all crystals would show simple cobalt (Co) diffusion profiles, meaning high cobalt concentrations at the crystal edge, changing gradually to lower concentrations in the crystal core. This has been well described by Saeseaw et al. (2015). For the deep blue crystals, the result was as expected: high cobalt, thousands of atomic parts per million (ppma) at the crystal edge, changing gradually to low cobalt in the crystal core. This is clear evidence of cobalt diffusion treatment. However, all other crystals (i.e., those that were not deep blue) showed something quite different. The cobalt concentration in these crystals was negligible, generally below a few atomic ppm. The nickel (Ni) concentration, conversely, was extremely elevated, around 5,000 to 30,000 ppma at the rim and dropping to a few ppma in the crystal core. An initial conclusion was made that these “cobalt-diffused” spinel crystals were not cobalt-diffused at all, but rather nickel-diffused. Subsequent investigations using various absorption, luminescence, and fluorescence techniques, along with gemological observations, confirmed that the samples were indeed nickel-diffused and that natural spinel was used as the starting material. Additionally, nickel was confirmed to be the main chromophore responsible for the modified color. These observations are described in detail below, along with recommended identification criteria.
GEMOLOGICAL OBSERVATIONS
A total of 18 stones were studied. Standard gemological testing was consistent for spinel. Refractive indices were generally 1.718, but some samples varied up to 1.721, possibly due to the increased concentration of nickel at the surface. All samples were inert in long-wave UV light. Most were inert to short-wave UV, but a few showed faint chalky yellow fluorescence near the edges when prepared as doubly polished slabs. All faceted stones had a weak to strong red reaction when viewed through the Chelsea color filter. The doubly polished slabs viewed in this way showed color zonation: red at the rims and colorless in the centers.

Figure 2. Nickel-diffused spinel shows subtle color concentration along facet junctions (A and B) and features suggesting flux-assisted healing of the fractures during the heating process (C–F). Photos by Aaron Palke; fields of view 10.24 mm (A), 2.90 mm (B), 2.34 mm (C and D), 1.76 mm (E), and 1.99 mm (F).
When immersed in methylene iodide, the faceted stones showed a strong concentration of color around the rim of the stone, sometimes with additional subtle color concentration along the facet junctions (figure 2A). Microscopic observations sometimes showed this same color concentration along facet junctions, particularly at the keel of the stones (figure 2B), although the effect was more subtle than seen in other treated material, such as titanium-diffused sapphire. The most striking microscopic feature was the abundance of artificially healed fractures, likely associated with the presence of a flux material during the heating (figure 2, C–F). This is also supported by the trace element data, described below, which show high amounts of lithium at the crystal edge—lithium is a common component of flux material.
TRACE AND MINOR ELEMENT CONCENTRATIONS AND PROFILES
Even without quantification, the high nickel concentrations are obvious in X-ray fluorescence spectra (figure 3). These show clear peaks associated with nickel, with the main peak being the Kα emission line at around 7.47 keV. No samples from this suite showed fluorescence associated with cobalt.

Figure 3. An XRF spectrum of a nickel-diffused spinel (sample 17407067; see inset photo) acquired at 12 kV with an aluminum filter. Clear nickel fluorescence peaks are visible. The position of the main cobalt peak, absent in this spectrum, is shown.

Figure 4. A: Nickel concentrations measured on the girdles of nickel-diffused stones, along with the range of nickel concentrations seen in a subset of spinel crystals submitted to GIA. This subset includes natural, unheated spinel with the following hues: blue, bluish green, greenish blue, blue-green, green-blue. The nickel concentrations are considerably higher (100–10,000x) in the nickel-diffused stones. Also shown are the concentrations of lithium (B) and beryllium (C), both of which are also elevated at the crystal rims, as shown in the LA-ICP-MS transect (figure 5). Lithium concentrations are generally higher than the natural range, but beryllium concentrations are indistinguishable.
The concentration of nickel at the edge of the crystals was high, around 10000–30000 ppma (table 1), as measured using LA-ICP-MS spot analyses on the girdles of 13 stones. These nickel concentrations are very high when compared to natural gem-quality spinel submitted for analyses at GIA (figure 4A). It should be noted, however, that end-member nickel-spinel (chihmingite, NiAl2O4) has been found in nature.
Along with elevated nickel, some but not all crystals also showed high lithium (Li) concentrations, up to around 3000 ppma. Such high lithium is rare in natural, untreated gem spinel (figure 4B). Concentrations of other elements, even if added or removed during the diffusion treatment, were generally within normal ranges for gem spinel. Notably, this also includes beryllium (Be, figure 4C), despite beryllium showing increasing concentration toward the crystal edge in the LA-ICP-MS transect, described below (figure 5).

Additionally, the concentrations of all other measured elements were highly variable between stones. This implies either different treatment conditions or different starting materials. Preliminary analyses from the cores of some doubly polished slabs (not presented) showed different concentrations of elements other than Ni (those analyzed in table 1) in areas apparently unaffected by diffusion, suggesting that these concentration differences relate at least partially to different starting materials rather than different treatment conditions. At this point, however, we cannot confidently describe the nature of the starting materials.
Overall, the data show that nickel is a weak chromophore, as thousands to tens of thousands of ppma led to relatively weak colors. In contrast, cobalt diffusion treatment requires only a few hundred to thousands of ppma cobalt to create deep blue colors.

Figure 5. Concentrations of nickel, lithium, iron, zinc, vanadium, titanium, beryllium, manganese, gallium, chromium, and cobalt recorded along a ~3.3 mm culet-to-table transect across a slab cut from the core of a nickel-diffused spinel crystal (sample 17407124). Notably, nickel shows an extreme concentration decrease from rim to core, whereas cobalt shows a very small decrease with sub-ppm concentration along the whole transect.
In the crystal where trace element concentrations were recorded along a central transect (sample 17407124), nickel, lithium, beryllium, zinc (Zn), manganese (Mn), and cobalt show decreasing concentrations from the rim to the core (figure 5). All show U-shaped profiles. Ni shows the largest concentration change, from ~1 ppma in the core to ~5000 ppma at the rim. Cobalt shows the smallest change, from ~0.4 ppma at the core to ~0.8 ppma at the rim. Conversely, vanadium (V), iron (Fe), and magnesium (Mg) show inverted U-shaped profiles—i.e., lower concentrations at the rim than at the core—although the Mg profile cannot be accurately resolved using our LA-ICP-MS method. The Mg profile can be resolved using energy-dispersive spectroscopy (EDS), though, as described below. Chromium (Cr) and titanium (Ti) show variable concentrations, but neither show clear U-shaped or inverted U-shaped profiles. Gallium (Ga) shows no apparent concentration change.

Figure 6. Maps of nickel, magnesium, and aluminum recorded by energy-dispersive spectroscopy (EDS) from sample 17407069. Colors represent counts on nickel, magnesium, and aluminum normalized to total signal intensity by dividing by counts on oxygen (all Kα lines). The normalization was necessary given non-constant total signal across the mapped area. Color scales are set to maximize contrast; the ranges (normalized to O) are 0–0.04 for Ni, 0.85–1.2 for Mg, and 1–2.6 for Al. Also shown are profiles of magnesium and nickel, extracted from the maps in table-culet transects.
A central portion of another doubly polished slab (sample 17407069) was also mapped using EDS (figure 6), to complement the data from LA-ICP-MS analyses. This method has considerably higher spatial resolution than LA-ICP-MS but suffers from much poorer detection limits, so the only elements in the spinel that could be measured were nickel, magnesium (Mg), aluminum (Al), and oxygen (O). Nickel shows a clear concentration decrease from rim to core. Magnesium shows the opposite, and aluminum shows no apparent zonation. The zonation pattern of nickel conforms to the faceted stone’s shape, which implies that the diffusion treatment was conducted after faceting. This is consistent with the presence of color concentration at facet junctions.

Figure 7. UV-Vis spectra recorded from the near-rim regions of doubly polished slabs fabricated from nickel-diffused spinel crystals (lower four curves). Absorption coefficient is calculated as 2.303 x absorbance/thickness (cm). These were recorded by placing the stone over a 0.5 mm circular aperture, located as close as possible to the crystal edge at the table. Images of the stones are shown, along with 1 mm scale bars (solid gray lines). Also presented are concentrations of nickel recorded using a 50 μm LA-ICP-MS spot, centered at 50 μm from the crystal edge. This gives an approximation of the relative (between stones) nickel concentration, but is likely an overestimation of the mean nickel concentration in the area from which the UV-Vis spectrum was recorded given the nature of the nickel concentration gradients. Also shown are spectra recorded from a lab-grown nickel-doped MgAl2O4 powder and single crystal (Jouini et al., 2007; Serment et al., 2020); a lab-grown nickel-doped ZnAl2O4 powder (Lorenzi et al., 2006) and a cobalt-diffused spinel. The positions of the main bands in the nickel-diffused material are denoted by dashed lines.
ULTRAVIOLET/VISIBLE SPECTROSCOPY
Ultraviolet/visible (UV-Vis) spectra were recorded from the rims of several double-polished slabs (17407057, 17407126, 17407123, 17407124), using a 0.5 mm circular aperture. In all cases, the main peaks were at 369, 381, 475, 597, and 639 nm (figure 7). These positions are consistent with those present in spectra recorded from nickel-doped spinel powders synthesized for use as cyan dyes (Serment et al., 2020), nickel-doped single crystal spinel (Jouini et al., 2007), and nickel-doped gahnite spinel (ZnAl2O4; Lorenzi et al., 2006).
The peaks at 597 and 639 nm were assigned in this study to nickel in tetrahedral coordination (i.e., nickel generally replacing Mg2+). The peaks at 369 and 381 nm were associated with nickel in octahedral coordination, meaning nickel generally replacing Al3+. The band at 475 nm was not specifically defined by Serment et al. (2020), but it is notable that stones with a more intense 475 nm band appear to show a more green color. Figure 7 also shows a spectrum recorded from a cobalt-diffused spinel, obtained in the same parcel as these nickel-diffused crystals, showing clearly different absorption band positions.
The similarity between the absorption spectra from the nickel-diffused crystals, and a spectrum of single-crystal nickel-doped spinel grown in an argon atmosphere, suggests that the nickel is predominantly Ni2+, which would also likely be favored over Ni3+ at the high temperatures of diffusion treatment (likely 1600°C or higher).

Figure 8. PL spectra recorded from the rim (i) and core (ii) of a nickel-diffused natural spinel (sample 17407124), showing features characteristic of heating. Also shown is a spectrum from a natural, unheated high-nickel crystal (iii; >300 ppma Ni). Spectra are offset for clarity.
PHOTOLUMINESCENCE SPECTROSCOPY
Photoluminescence (PL) spectra recorded with 514 nm excitation are shown in figure 8. Spectra of the nickel-diffused stones are similar to natural, heat-treated spinel, which is in line with visual observations of inclusions and refractive indices. As with most natural spinel, the spectra are dominated by bands attributed to chromium. The spectra show broadening of the band(s) at around 686 nm. PL spectra recorded near the crystal rims are different from those recorded in the cores, with the rim spectra showing a dominant band at 687.5 nm, and core spectra showing a strong doublet with maxima at 685.6 and 687.3 nm. This may be associated with nickel, but it is notable that a spectrum recorded from a natural, unheated spinel with relatively high nickel (around 350 ppma) did not clearly show this feature. Spectra recorded from faceted stones using non-confocal PL spectroscopy will likely show some combination of these spectra.
DIFFUSION RATES AND MECHANISMS
The length scales over which the concentrations of the diffusing elements change, defined as the characteristic diffusion length, increases in the order V<Mn<Fe<Zn≈Co≈Ni<Be<Li (figure 5), suggesting a similar order for the relative diffusion coefficients. In other words, lithium diffuses more rapidly than vanadium.
The decrease in magnesium concentration from the core of the crystal to the edge (figure 6), associated with an increase in nickel concentration, is consistent with nickel addition associated with the removal of magnesium from the crystal. This would imply that the nickel primarily occupies the crystallographic site usually occupied by magnesium—i.e., the tetrahedral site in spinel. This is consistent with the UV-Vis spectra, where all crystals show predominantly tetrahedral nickel. Additionally, this is the expected mechanism of nickel incorporation, because the ionic radii for Ni2+ and Mg2+ are similar: 0.55 and 0.57 Å respectively (Shannon, 1976).
Some also show nickel in octahedral coordination, implying nickel on the aluminum site. This is expected at the high temperatures of diffusion treatment, which are unknown but possibly >1500°C. At these temperatures, spinel becomes disordered, meaning cations swap between sites.
The shapes of nickel diffusion profiles—i.e., the forms of concentration versus distance data in figure 5—correspond almost perfectly to the error function, a mathematical function often used to describe the shapes of diffusion profiles. Simply, this means that there is a smooth decrease in nickel concentration, and associated color, from the edge of a crystal to the core. This implies that diffusion in this system is relatively simple, with little or no trapping behavior—such non-simple behavior could be expressed as sharp color changes, as is often observed in titanium-diffused sapphires, for example. The likely diffusion mechanism would then involve simple exchange of Mg (tetrahedral) vacancies with Ni2+, which has been proposed as one mechanism of Cr3+ diffusion in spinel (Posner et al., 2016).
SUMMARY OF CRITERIA FOR IDENTIFICATION
According to our current study of these stones, the following criteria are proposed for identification of nickel diffusion treatment in spinel:

High concentrations of nickel at the crystal faces, potentially thousands of atomic parts per million or more. This may be associated with high lithium concentrations.
Photoluminescence spectra characteristic of heated, natural spinel, although the possibility of treatment of lab-grown spinel is not ruled out.
Characteristic UV-Vis absorption spectra, with bands at around 370, 470, and 600 nm.
Subtle color concentrations at the facet junctions, although this may be limited if the stones are repolished after treatment.
Textures associated with flux-assisted healing of fractures.

Overall, the treatment should be readily identifiable using standard gemological techniques and equipment. @chapter:12


Publication Year: - Title: Spring into Summer: Gems in Alluring, Vibrant Colors Abstract: Nearly 600 sapphires create the radiant flowers on this blackened gold brooch with tsavorite garnet leaves. This floral creation highlights the 2014 Color of the Year, Radiant Orchid. Gift of Dr. Gary R. and Barbara E. Hansen, photo by Robert Weldon/GIA

                      The Pantone Color Institute – an arbiter of color for designers and aficionados alike – chooses 10 shades for its spring and fall seasonal color reports. Ranging from purple and blue to orange and yellow, the selections for spring into summer 2014 are sure to spark your interest and inform your fashion choices. This year’s chosen colors are a mix of alluring pastels and vibrant neon hues.

Gemologists know that many gems come in a variety of colors, just like many of these Pantone colors can be seen in a variety of gems. From cool blue aquamarines and radiant pinkish purple sapphires to sizzling orange fire opals, explore some of the gems that match this season’s on-point colors in the photo gallery below.

View Gallery @chapter:25