Gem News International Gems & Gemology, Winter 1990, Volume 26, No. 4

Winter 1990 Gem News International

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Diamonds
            DeBeers Announces World's Largest Synthetic Diamond Crystal
            China-Cut Diamonds Sold in Singapore
            Guyana Mining Development
Colored Stones
            Possible Foreign Participation in Afghan Mining
            Novel Assembled Stone
            Black Coral Industry on the Mexican Caribbean
            Update on Sapphire Mining in Kanchanaburi
            Peace Pact for Colombian Emerald Region
            Unusual Color-Zoned Garnet
            Heavy Liquids Studied in Australia
            Black Cat's-Eye Opal
            Exceptionally Large White Opal
            Color-Change Cobalt Spinel
            Large Topaz Sculpture
            Cat's-Eye Bicolored Tourmaline
            More Gems from the USSR?
Enhancements          
            Diffusion-Treated Sapphire Update
            "Rainbow" Quartz: A New Enhancement
            Jade "Processing"
Synthetics and Simulants
            Natural-Appearing Synthetic Cabochons
            Thailand Cutting CZ
            Glass Imitation Jadeite
            A Glass Imitation Pectolite?
            Dyed Quartz Imitation of Sugilite?

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