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A face-up view of a cushion cut diamond with blue color.
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Gems & Gemology’s 7 Most Unusual Encounters from 2019

Check out some of the most interesting and unusual diamonds and coloured stones submitted to GIA’s laboratories in 2019.

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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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A History of Diamond Treatments

Modern gemmologists and diamantaires are faced with a broad spectrum of colour and clarity treatments ranging from the simple to the highly sophisticated.

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10 Study Samples Before and After HPHT Processing
GE POL Diamonds: Before and After

This article explores and identifies the changes that type IIa GE POL diamonds experience before and after HPHT annealing.

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A New Lasering Technique for Diamond
A New Lasering Technique for Diamond

Several diamonds were treated for the purposes of observation and report with a new laser technique which does not show the typical surface-reaching drill hole.

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UV/Vis/NIR Absorption Spectrum
Spectroscopic Evidence of GE POL HPHT-Treated Natural Type IIA Diamonds

Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.

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Clues to the Process Used by General Electric to Enhance the GE POL Diamonds

General Electric has developed a variety of high-temperature annealing techniques at different pressures for enhancing the optical properties of polycrystalline synthetic diamond films and single-crystal synthetic diamond.

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Synthetic Moissanite: A New Diamond Substitute

Synthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation; this article reports on how to identify and characterise it.

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Natural diamond
A Chart for the Separation of Natural and Synthetic Diamonds

Exploration of a chart designed to give jewellers and gemmologists a practical guide to identifying synthetic diamonds as they enter the jewellery trade.

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An Update on Filled Diamonds: Identification and Durability

This report focuses on recent products from Yehuda/Diascience, Koss & Schecter Diamonds (Genesis II) and Clarity Enhanced Diamond House (a subsidiary of Goldman Oved Diamond Co.).

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