Gems of Northern Madagascar Video with GIA Field Gemology
Learn all about the gems of Northern Madagascar in this exciting video with Wim Vertriest, GIA Manager of Field Gemology.
Micro-Features of Beryl
Provides a visual guide to the internal features of different varieties of beryl.
Gems Recovered from Sedimentary Rocks
Explores the formation of sedimentary rocks, gems found and formed in sedimentary environments, and the alluvial mining of these gems.
Bohemian Garnets as Decorative Materials for Glass Vessels from the Late Sixteenth to Early Eighteenth Centuries
Examines a technique for setting cut garnets on glass objects, invented by Claudius vom Creutz of Nuremberg in the late sixteenth century.
Topaz from Mason County, Texas
A comprehensive look at Texas topaz, detailing its gemological and compositional characteristics and providing a basis for using trace element concentrations to identify its origin.
A Unique Petrified Tree Fern from Northeast China
Documents the gemological properties, chemical composition, and appearance of petrified tree fern discovered in northeast China.
Slovak Opal: A New Life for a Historical Gem
Reports on the recent production of precious and common opal from a centuries-old locality.
Trapiche Garnet from Vietnam
A rare occurrence of 14 trapiche patterns is observed in a garnet sample from Vietnam.
Hollandite in Amethyst
A spectacular display of hollandite crystals is captured within an amethyst cabochon.
Treated HPHT Laboratory-Grown Diamond with Dramatic Color Zoning
A Fancy Deep brownish orange treated HPHT-grown diamond exhibits multiple defect concentrations in various growth sectors.
Distinctive Feather in Diamond
A feather observed in a natural diamond resembles a large reptile.
Unusual Inclusions in Natural Emerald from Chivor
Tubular three-phase inclusions are observed in a Colombian emerald.
Solid Laboratory-Grown Single-Crystal Diamond Ring
The quality and size of this 4.04 ct CVD-grown diamond ring demonstrate the advancing technology in laboratory-grown diamonds.
Etch Features Reveal the Morphology of Diamond
Trigons and tetragons observed in a chameleon diamond indicate both octahedral and cubic growth.
Yellow Sapphire: Natural, Heat-Treated, Beryllium-Diffused, and Synthetic
Investigates the various chromophores responsible for color in four types of yellow sapphire.
Special Colors and Optical Effects of Oregon Sunstone: Absorption, Scattering, Pleochroism, and Color Zoning
Details the colors and optical effects caused by metallic copper inclusions in this gem-quality feldspar.
Spring 2022 Auction Highlights
Large near colorless, blue, and yellow diamonds broke auction records at Christie’s and Sotheby’s in the first half of 2022.
Combination of Phenomena in Star and Cat’s-Eye Color-Change Sapphire
Both asterism and chatoyancy are observed in a color-change sapphire.
The Type IIb De Beers Cullinan Blue Diamond
GIA’s New York laboratory reports on a 15.10 ct Fancy Vivid blue cut-cornered rectangular step cut named the De Beers Cullinan Blue diamond.
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