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Article
Pyrope Garnet and Montana Sapphires Highlight Winter 2015 G&G

G&G Brief presents an overview of the content of the Winter 2015 issue of Gems & Gemology.

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Article
Fall 2015 G&G: Trapiche Emeralds, Synthetic Diamonds and a Large Diamond Source

G&G Brief presents an overview of the content of the Fall 2015 issue of Gems & Gemology.

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Optical Defects in Diamond: A Quick Reference Chart

A simple chart on optical defects in diamond, including those that produce coloration and fluorescence colors.

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Non-nacreous Pen Pearls
Observations on Pearls Reportedly from the Pinnidae Family (Pen Pearls)

Examines the internal structure, chemical composition, and spectroscopic features of 22 pen pearls.

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Jadeite boulder from Itoigawa, Japan
Japanese Jadeite Tables

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

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Iridescence in iris quartz from Jalgaon, India
Causes of Iridescence in Natural Quartz

Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.

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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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Article
GIA Gem Project
Various Gems
(Amblygonite - Axinite)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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Article
GIA Gem Project
Corundum

Ruby and sapphire (usually blue, but also in every other color) have been the most important colored gemstones for several thousand years. Originating historically in southeast and central Asia, and more recently in eastern Africa, these colored varieties of the mineral corundum have been much sought as gems because of their rarity, color and durability. Gem corundum can display asterism and chatoyancy due to the presence of oriented mineral inclusions, and in some cases, a change of color when viewed under different light sources.

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Article
GIA Gem Project
Various Gems (Olivine - Rutile)

Among the collection assembled by Dr. Edward Gübelin are a number of uncommon gemstones from many worldwide localities.

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