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Mozambican ruby with signs of heat Treatment
Colored Stones and Pearls

Poster abstracts on “Colored Stones and Pearls” from GIA’s 2018 International Gemological Symposium.

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Color distribution in nitrogen-doped CVD after irradiation and annealing
Diamond Identification

Poster abstracts on “Diamond Identification” from GIA’s 2018 International Gemological Symposium.

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Star rhodochrosite from the Sweet Home mine, Colorado
Colored Stones and Pearls

Abstracts of speaker presentations from the “Colored Stones and Pearls” session of GIA’s 2018 International Gemological Symposium.

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Inclusion features in Zimmi diamonds
Diamond Geology

Abstracts of speaker presentations from the “Diamond Geology” session of GIA’s 2018 International Gemological Symposium.

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Canary yellow diamond
Diamond Identification

Abstracts of speaker presentations from the “Diamond Identification” session of GIA’s 2018 International Gemological Symposium.

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Irradiated 1.06 ct brownish orange HPHT synthetic diamond
Photoluminescence Mapping of Optical Defects in HPHT Synthetic Diamond

Demonstrates the importance of this method in identifying diamond treatments, based on the analysis of PL maps acquired from a brownish orange HPHT synthetic diamond.

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5.03 ct Fancy Deep Blue HPHT Synthetic Diamond
Largest Blue HPHT Synthetic Diamond

Analysis of a 5.03 ct HPHT-grown blue synthetic diamond, the largest ever examined by GIA.

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Fluorescence image of Aurora Butterfly of Peace
An Introduction to Photoluminescence Spectroscopy for Diamond and Its Applications in Gemology

Presents the underlying physics and methodology of this analytical technique, which has become an essential tool in identifying treated and synthetic diamonds.

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

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

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Fancy Black Nano-polycrystalline Diamond
A Larger, Higher-Quality NPD Synthetic Diamond

GIA’s New York laboratory recently detected an undisclosed NPD synthetic diamond, a 1.51 ct Fancy Black round.

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