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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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.
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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.
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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 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.
Read MoreA large number of natural-colour yellow diamonds are analysed using grading and appearance aspects among other characteristics to clarify the differences between them and the light yellow diamonds associated with GIA's D-to-Z colour grading scale.
Read MoreThe stories behind seven strikingly beautiful rare natural diamonds, united in an exhibit at the Smithsonian, are told here.
Read MoreKnown for their great beauty and rarity, pink diamonds have long been sought after by jewellers, collectors and consumers.
Read MoreMore than 400 blue diamonds were studied at the GIA Gem Trade Laboratory over several years to reveal additional information about the relationships between their colour, clarity and other gemmological properties.
Read MoreHow GIA’s Gem Trade Laboratory grades coloured diamonds, including an expanded colour grading terminology, is explained.
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