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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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Natural-Color Pink, Purple, Red, and Brown Diamonds: Band of Many Colors

Summarizes data collected by GIA on more than 90,000 natural diamonds in this color range and presents their gemological and spectroscopic properties.

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Major colors of HPHT synthetic diamonds
Observations on HPHT-Grown Synthetic Diamonds: A Review

Summarizes statistical data and distinctive features of several thousand gem-quality HPHT synthetic diamonds examined by GIA from 2007 through 2016.

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Jadeite boulder from Itoigawa, Japan
Japanese Jadeite: History, Characteristics, and Comparison with Other Sources

Examines the sources, color, texture, and chemical composition of jadeite from Japanese deposits.

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Eight natural-color pistachio pearls
Identification of “Pistachio” Colored Pearls Treated by Ballerina Pearl Co.

A report on the color treatment process for these intensely greenish yellow to yellowish green cultured pearls and the techniques for identifying them.

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Pearl farm on the Indonesian island of Lombok
Bead-Cultured and Non-Bead-Cultured Pearls from Lombok, Indonesia

Documents the retrieval and testing of P. maxima cultured pearls from a Lombok hatchery.

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A group of rings featuring alexandrite from Brazil
Geographic Origin Determination of Alexandrite

The geographic source of this rare color-change gem has a significant impact on value. Trace element chemistry profiles allow GIA to accurately determine origin for alexandrite from several countries.

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Colombian emerald crystal
Geographic Origin Determination of Emerald

The relative chemical diversity of emeralds from different deposits worldwide allows clear origin determination in most cases. This contribution explains the criteria used by GIA to make geographic origin conclusions for emeralds.

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Inclusions in Natural, Treated, Synthetic, and Imitation Opal

Provides a visual guide to the internal features of natural, treated, synthetic, and imitation opal.

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Matched pair of Kashmir sapphires
Geographic Origin Determination of Blue Sapphire

In some cases, the value of a sapphire depends strongly on its geographic origin. This article details the origin data GIA has collected for blue sapphire and describes its methodology for using the data in geographic origin determination.

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