Many beautiful older diamonds are cut to different proportions than modern round brilliants, which makes them a challenge to grade according to modern cut conventions. This article describes how the GIA accommodates these historic gems.
Read MoreThis article describes what is known about the Wittelsbach Blue since it was first reported in 1666, and the gemmological information released to date on this diamond.
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The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds coloured grey to blue to violet.
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De Beers reduces rough prices at May sight, undisclosed treated diamonds submitted to GIA, and Sotheby’s and Christie’s sales break auction records − again.
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Knowledge of type allows gemmologists to better evaluate if a diamond might be treated or synthetic, and whether it should be sent to a laboratory for testing.
Read MoreKnown for their great beauty and rarity, pink diamonds have long been sought after by jewellers, collectors and consumers.
Read MoreOne of the most popular exhibits at the Smithsonian Institution, the stunning Fancy Dark greyish blue Hope diamond was formally graded by GIA’s gem laboratory.
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With the use of modern tools and technology, this article sheds light on the history and provenance of both the French Blue and the Hope diamonds.
Read MoreHow GIA’s Gem Trade Laboratory grades coloured diamonds, including an expanded colour grading terminology, is explained.
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This article, from the Autumn 2009 issue of Gems & Gemology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemology.
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