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Gemstones

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Recently discovered and legendary diamonds in the blue/gray/violet color range
Natural-Colour Blue, Grey and Violet Diamonds: Allure of the Deep

Summarises data collected on more than 15,000 natural blue/grey/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this colour range.

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Fancy Dark brown to Fancy black Marange diamonds
Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions

Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.

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Article
Cut: The 4th C

GIA began issuing reports that included a cut grade for round brilliant diamonds in 2006 in an effort to establish standards for cut in the same manner as it has for colour and clarity. This grading system is based on research conducted over the previous decade which was chronicled in several articles published in Gems & Gemology.

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Article
De Beers Reduces Rough Prices – Too Little?

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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Article
Describing 58-facet Round Brilliant-Cut Diamonds at GIA

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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RN Linares CVD
Article
CVD-Grown Synthetic Diamonds, Part 2: Properties

This article provides a brief overview of the properties of CVD-grown synthetic diamonds.

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Faceted CVD Synthetic Diamonds
CVD Synthetic Diamonds from Gemesis Corp

An examination of the gemmological and spectroscopic properties of CVD synthetic diamonds from Gemesis Corp.

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GIA’s Symmetry Grading Boundaries for Round Brilliant Cut Diamonds

A presentation of parameters used to support GIA's symmetry grading system.

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Coloured Diamonds in the Aurora Butterfly of Peace Collection
The “Type” Classification System of Diamonds and Its Importance in Gemmology

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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Colour Grading “D-to-Z” Diamonds at the GIA Laboratory

This article discusses the history and ongoing development of GIA's colour grading system, and explains how its laboratory applies it.

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