Winter 2014 - Volume 50, Issue 4
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Type IaB natural diamond
Natural Colorless Type IaB Diamond with Silicon-Vacancy Defect Center

Examination revealed a rare instance of a silicon-vacancy defect in natural diamond.

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Dark pink-purple spinel
Spinel Inclusion in Spinel

Examination of a pink-purple spinel revealed what appeared to be a spinel crystal inclusion.

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HPHT-grown synthetic diamond
Mixed-Type HPHT Synthetic Diamond with Unusual Growth Features

Although this stone bore some superficial resemblance to moissanite, its gemological properties were consistent with HPHT synthetic diamond.

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Burmese ruby beads
Lead-Glass-Filled Burmese Rubies

Beads from a multi-strand necklace were the first examples of lower-lead-content glass filling in Burmese rubies examined at GIA’s Carlsbad laboratory.

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Loose natural pearl aggregates
Natural Pearl Aggregates from Pteria Mollusks

Ten loose pearls with interesting shapes and internal growth features were from Pteria-species mollusks.

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CVD synthetic diamond
CVD Synthetic Diamond with Fancy Vivid Orange Color

Strong absorptions from N-V centers were the main cause of a CVD synthetic diamond’s pinkish orange bodycolor.

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Fancy Vivid yellow diamond
Very Large Irradiated Yellow Diamond

A very large diamond with a Fancy Vivid yellow color was identified as artificially irradiated.

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Group of intensely  colored round yellow diamonds
Screening of Small Yellow Diamond Melee for Treatment and Synthetics

Melee diamonds can be efficiently screened for synthesis and treatment using infrared absorption spectroscopy, DiamondView imaging, and microscopy.

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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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