Surface-treated topaz has become a viable alternative to topaz colored by irradiation. Unlike irradiation, which modifies the entire gemstone, coloration by chemical modification is limited to the ...

Synthetic diamond growth was first documented in 1952 by William Eversole of the Union Carbide Corporation, but it took another two decades before GIA issued the first grading report for a ...

The September birthstone is sapphire – a gem that’s been cherished for thousands of years. Although the term sapphire usually refers to the blue variety of corundum (ruby is the red variety), this ...

Demantoid, green andradite garnet, was discovered in the Central Ural Mountains of Russia in the mid-19th century. A favorite of the Czar's court, demantoid was another victim of the 1917 Bolshevik ...

瑞々しい青、鮮やかなバイオレット、濃い紫色のバランスを整えたエキゾチックなタンザナイトが発見される場所は、地球上でただ一つ、雄大なキリマンジャロ山の近くにあります。 タンザナイトの豊かな色相はサファイアの美しさに匹敵するほどです。

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania. The gem corundum is related to “dikes” of amphibolitic rocks ...

Hydrothermal synthetic red beryl has been produced for jewelry applications by the Institute of Crystallography and an affiliated company, Emcom Ltd., both in Moscow. Diagnostic identification ...

世界の二大ダイヤモンド生産企業、De Beers（デビアス）とAlrosa（アルロサ）は、この数ヶ月間で原石の売上げが激減したものの、現在のダイヤモンド市場は安定しており、米国のホリデー シーズンおよび中国の旧正月では堅調な需要が期待できると報告して ...

Copper-bearing tourmaline from Mozambique was first recovered in 2001, but its Cu content was not recognized until 2003, and it was not widely sold with its Mozambique origin disclosed until 2005. It ...

GIA is a charitable, nonprofit 501(c)(3) organization with a mission to ensure the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and ...

Brazil is currently the leader in overall production of amethyst. This article describes the author's visits to three of Brazil’s most important mining areas: Marabá, Pau d’Arco, and Rio Grande do Sul ...

アコヤ真珠、淡水真珠、南洋真珠、タヒチ真珠の品質を、世界有数の専門家がどのように決定しているかを学習します。GIA 7 Pearl Value Factors™（GIAの真珠の7つの評価要素™）について説明します。また、商品の美しさ、価値、品質の関係を促進するために ...