Although the source rocks of alluvial sapphires in Montana have never been discovered, inclusions and geo-chemistry of material from this location may give clues to their original source. Mineral inclusions in alluvial Montana sapphires, mainly from Rock Creek, were identified and compared with existing data. Topaz was a remarkable find in one of these samples; other newly identified mineral inclusions in Montana sapphire were allanite, anatase, chalcopyrite, and monazite. Together with the presence of calcium-rich plagioclase, alkali-feldspar, apatite, barite, phlogopite, a pyrochlore-group mineral previously called uranpyrochlore, and chromite/spinel, these inclusions may reflect a metasomatic origin for the sapphires. This is supported by their chemical composition, which largely coincides with sapphires of plumasitic/metasomatic origin. The secondary Montana sapphires analyzed in this study are characterized by mean values of Fe (4686 ppmw), Ti (58 ppmw), Ga (51 ppmw), Mg (35 ppmw), and Cr (21 ppmw). Fe-Mg-Ga ratios help to distinguish them from sapphires with overlapping properties, such as those from Umba, Tanzania, and Rio Mayo, Colombia.

Advances in technology and increased demand for lower-priced gem materials contributed to the proliferation of new treatments throughout the first decade of the 2000s. The developments that made the most difference were the diffusion treatment of corundum with beryllium, diffusion of copper into feldspar, clarity enhancement of ruby and diamond, and heat treatment of diamond, ruby, and sapphire. Gemological laboratories and researchers have done their best to keep up with these treatments, and the jewelry trade has struggled with how to disclose them. This article summarizes these developments and the methods used to identify the various enhancements.

Synthetic gems are superlative examples of crystal growth. Today, industrial and scientific crystal growth is a highly sophisticated endeavor employing a wide range of methods. Many of these have been adapted to grow gems for jewelry use. Most major gemstones have been synthesized, and these products are commercially available around the world, often at a fraction of the cost of a natural gem of comparable size and quality. Distinguishing them from their natural equivalents involves a number of interesting challenges. Inclusions (internal features) observed by microscopy often provide conclusive proof of synthetic origin. When routine testing procedures (refractive index, specific gravity, fluorescence, and internal inclusions) do not provide sufficient evidence, laboratories must employ more advanced analytical instrumentation.

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

Gem-quality rubies and pink to purple sapphires are being recovered from the Luc Yen and Quy Chau mining regions of Vietnam, This article briefly reviews the history and geology of these areas, as well as the mining methods used.The gemological characteristics of more than 100 of these stones are described in detail, The most notable internal features are blue color zones, swirl-lilze and angular growth features, bluish "clouds," and inclusions of rod-like calcite and pyrrhotite as well as the rare mineral nordstrandite.ntil recently, little was lznown about the gem poten-1 'a1 of Vietnam, in spite of the fact that it is surrounded by countries with significant gem riches.In 1983) however) corundum was reported near the towns of Ham Yen and An Phu! north of Hanoi, Major exploration began in 1987) when geologists brought to the attention of the local government their discovery of rubies near the town of Luc Yen, 28 lzm west of Ham Yenl in Yen Bai (formerly Hoang Lien Son) Province.In a five-month period!from November 1989 through March 19901 one deposit in the Luc Yen district produced more than three million carats of rough pinlz sapphire and ruby.Several other deposits are currently being worked in this gem-rich district.According to various trade sources) the finest rubies from this locality rival the finest stones from Myanmar [formerly Burma; see) e.g.) "Vietnam Claims Major Ruby Find," 1990;Hughes and Sersen, 1991;and Weldon, 1991).In December of 19901 rudimentary mining operations began at Quy Chau in Nghe An (formerly Nghe Tinh) Province, south of Hanoi.Stones examined thus far from this latter deposit compare favorably with those mined at Luc Yen (figure 1).Two of the authors, Messrs. Khai and Khoa! have been involved in the geologic study of the gem deposits of Vietnam and the marketing of the stones recovered.Messrs. Mora and Repetto are participating in a joint venture between the Italian firm Tecno-Resource [a subsidiary of FIMO Inc., of Switzerland) and the Vietnamese government to establish a cutting operation and gemological laboratory in Vietnam.They provided GIA with numerous samples of rubies and pinlz to purple sapphires obtained in Vietnam, which formed the basis of the current research.This article reviews the Luc Yen and Quy Chau mining regions) and provides a gemological characterization of the rubies and fancy sapphires found there.Vietnamese geologists believe that there is consider-136 Rubies and Sapphires from Vietnam

White, pink, and black nontransparent synthetic "cubic zirconia" is currently being manufactured in Russia and marketed primarily in cabochon and bead form.These unusual materials are potentially useful as substitutes for such gem materials as pearl, dyed black chalcedony ("onyx"), and even black diamond.The authors provide a detailed description of these new products, including the chemistry and probable manufacturing techniques.These products can be readily identified by standard gemological tests.Synthetic cubic zirconia (CZ) is best known as a transparent, essentially colorless diamond simulant.Few would argue that, to date, it is the most effective imitator of that important gem.Annual production now exceeds one billion carats (Nassau, 1990).In 1989 alone, Thailand exported 13,256 kg (66,280,000 ct) of fashioned C Z ("Thais cut more CZ," 1990).

Green grossular garnet crystals o f fine form and clurity have been found recently in Tanzania, at the Karo pit of the tanzunite mining belt.Although the crystals tend to be relatively light in color, they are consistent in gemological properties and composition with the grossular variety popularly 1<11own as tsavorite.The very distinct and complex morphology of these crystals is remarkable.Eight different crystallographic forms have been identified, including one that has never before bean recognized for any member of the garnet group.

The approximately 41-ct Dresden Green diamond is the largest, and perhaps the finest, green diamond known to have a color of natural origin. A diamond so rich in. history is well worth studying for that reason alone> but the Dresden Grem offers the unique opportunity of adding valuable data to the quest for means to distinguish natural from laboratory-inadiated green diamonds. In November of 1988, two senior GIA staff members visited the Green Vaults with this goal in mind. The Dresden Green diamond proved to be not only of extraordinary quality but also a vary rare type IIa-me of the purest f o i m s of diamond. In addition, the spectial characteristics of this stone were found to overlap those of k n m treated diamonds. The history locality o w , and properties of the Dimden Grem diamond are discussed in detail in this article,

Blue diffusion-treated sapphires are becoming more prevalent than ever before. The diffusion technique, which involves the addition of color-causing chemicnls during heat trentment, results in a thin layer of color at the surface of colorless or light-colored sapphire. The color was found to be stable to routine cleaning procedures; however, it may be partially or completely-removed if the stone is repolished pf, recut. Recently, significant quantities o f so-called "deep" diffusiontreated sapphires have entered the market. This article documents the properties of these and other blue diffusion-treated sapphires, and presents means o f identifying this method using simple gemological tests.

During the 1970s and 1980s, treasure hunters discovered the centuries-old remains of the sunken Spanish galleons Nuestra Senora de Atocha and Santa Margarita.Not only did they find massive amounts of silver and gold in coins, bars, and chains, but they also uncovered a number of rough emeralds and several pieces of emerald-set jewelry.Recently, some of the treasures recovered from the Atocha were examined at the Santa Monica office of the GIA Gem Trade Laboratory.Gemological testing of the emeralds revealed inclusions typical of stones mined in Colombia as well as possible evidence o f extended submersion in s e wter.Study of the jewelry revealed a highkarat gold content and fine workmanship that represented methods typical of the era.

Infrared spectroscopy provides a menns to distin-g~1is11 n a t ~~r a l from synthetic alexandrites in the range 2000-4200 c m -I , as dcterrr~ined by a study o f spectrtr obttrined from 15 natrrral and 28 synthetic alexandrites from a variety o f sources.The technique is nondestrrrctive and, with Fourier trnnsfornl instrunlcntalion, extremely rapid.It is especially ~l s e f u l for identifying stones that conttlin I I O distingrrishing inclusions.