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Spinel rough from Tajikistan, the largest stone (upper right) weighing 242.50ct.
Article
Distinguishing Heated from Unheated Spinel

While top-quality natural spinels have so far escaped large-scale treatment processes, some heat-treated goods are on the market. This report establishes the identifying criteria of heated spinels.

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A clear multi‐phase inclusion in jeremejevite. Magnified 128x.
Article
Jeremejevite: A Description of a 400 Crystal Collection from Namibia and a Preliminary Study

A collection of rare jeremejevites, reportedly from Namibia, was recently brought to the GIA laboratory in Bangkok for research purposes. This article reports on initial testing of five samples and photos of the entire collection.

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Article
Separation of Plagioclase Feldspars via Chemical Analysis

Examines the geographic origin of feldspar based on chemistry and refutes allegations that Mexican material is being sent to China for treatment and sold as Chinese material. Samples from Mexico, Mongolia and the United States are analysed.

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This 6.3 ct purplish pink sapphire is the first of this colour in which our laboratory detected natural Be with Ta and Nb.
Article
Beryllium in Pink and Yellow Sapphires

Describes a pink sapphire with natural beryllium and a yellow sapphire with an indeterminate beryllium source

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Understanding microscopic structures sheds light on the appearance and characteristics (such as lustre and hardness) of pearls and shells.
Article
Crystallographic Orientation of Biogenic Aragonite in Pearls

Explores the potential of laser Raman spectroscopy for material identification in pearls as well as determining the orientation of their biogenic mineral growth.

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Some of the specimens used for this report. The rough specimens on the left represent the starting material, the specimens top and right represent the treated rough, and the specimens at centre are cut from the treated rough.
Article
A Discussion of Ruby-Glass Composites

Describes several rubies treated with glass and experiments on rubies treated with glass, demonstrating that the stones are bonded together by the glass.

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While it is not possible with current gemmological microscopes to resolve the interior of any of the fluid inclusion islands in this “fingerprint”, the glassy fringe of microcracks along the edge provides evidence of high-temperature heat treatment.
Article
The Role of Secondary Fluid Inclusions in Detecting Heat Treatment

Examines what happens to secondary fluid inclusions (also known as "fingerprints") at extremely high temperatures, and their usefulness in detecting heat treatment.

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These 0.28–0.67 ct CVD-grown diamonds displayed intense pink colourations, and were colour-graded as Fancy Intense to Fancy Vivid pink or purplish pink. The samples were produced using “standard production techniques” at Apollo for this type of stone.
Article
CVD-Grown Pink Diamonds

An examination of seven CVD synthetic diamonds with an attractive pink colour.

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Ruby crystal associated with massive pyrite crystals seen at the Chittakatta ruby mines, Nangimali area, Pakistan controlled Kashmir.
Article
Sapphires Reportedly from the Batakundi/Basil Area

A preliminary examination and comparison with rubies and pink sapphires from other deposits in Central Asia.

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Pailin rubies and sapphires as seen at the morning gem market in Pailin.
Article
Concise Field Report, Volume 1: Pailin, Cambodia

A summary of two expeditions to the important ruby and sapphire deposits of Pailin, in late 2008 and early 2009. Includes a look at rough and faceted samples.

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