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The Gemological Institute of America (GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. [ 1 ] Founded in 1931, GIA's mission is to protect buyers and sellers of gemstones by setting and maintaining the standards used to evaluate gemstone quality.
American Gem Society (AGS), also known as American Gemological Society – American trade association; American Geosciences Institute (AGI) – Nonprofit scientific federation including around 50 geoscientific organizations founded in 1948; American Geophysical Union (AGU) – Nonprofit organization of geophysicists
Gemstones have no universally accepted grading system. Diamonds are graded using a system developed by the Gemological Institute of America (GIA) in the early 1950s. Historically, all gemstones were graded using the naked eye. The GIA system included a major innovation: the introduction of 10x magnification as the standard for grading clarity.
Sri Lanka, geologically speaking is an extremely old country. Ninety percent of the rocks of the island are of Precambrian age, 560 million to 2,400 million years ago. The gems form in sedimentary residual gem deposits, eluvial deposits, metamorphic deposits, skarn and calcium-rich rocks. Nearly all the gem formations in Sri Lanka are located ...
The Logan Sapphire brooch, National Museum of Natural History, Washington, D.C. The Logan Sapphire is a 422.98-carat (84.596 g) sapphire from Sri Lanka.One of the largest blue faceted sapphires in the world, it was owned by Victor Sassoon and then purchased by M. Robert Guggenheim as a gift for his wife, Rebecca Pollard Guggenheim, who donated the sapphire to the Smithsonian Institution in 1960.
Gemologist, Chairman of Board of Governors of Gemological Institute of America Richard T. Liddicoat, Jr. (March 2, 1918 – July 23, 2002) was an American gemologist . An educator in gemology, he contributed in the area of diamond quality grading and gem identification.
Gems & Gemology is a quarterly scientific journal published by the Gemological Institute of America. Each issue is devoted to research on diamonds , gemstones , and pearls . Topics include geographic sources, imitations and synthetics, treatments, and identification techniques.
Sri Lanka 392.52 carats Cushion Blue Anonymous owner Logan Sapphire [82] Sri Lanka 422.99 carats Cushion Blue National Museum of Natural History, Washington Queen Marie of Romania [83] Sri Lanka 478.68 carats Cushion Blue Anonymous owner Star of Adam [17] Sri Lanka, 2015 1404.49 carats Star Blue Anonymous owner Star of Bombay: Sri Lanka 182 ...