Spring 2013 - Vol. 49, No. 1
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Fancy intense pinkish orange diamond
Orange Diamond with Unusual Color Origin

GIA recently examined a rare orange diamond that demonstrated the complexity of diamond color origin.

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146725-SP13-LN
Large HPHT-Treated Fancy Pink Diamond

The New York lab encountered another large HPHT-treated diamond that showed stronger pink coloration.

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DiamondView Imaging of the Pavilion Facets
Pseudo-Synthetic Growth Structure Observed in Natural Diamond

This stone was a good example of a very rare natural diamond exhibiting synthetic growth characteristics.

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146736-SP13-LN
Green Diamond Treated with Radioactive Salt

The stone owes all of its green color to these shallow radiation stains.

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SP13 LN Fig.21
Yellow Synthetic Sapphire Colored by Trapped-Hole Mechanism

A combination of trace-element analysis and UV-visible spectroscopy clearly indicated that the yellow color originated from the much more effective chromophore known as “trapped holes,” associated with the trace amount of Mg and Cr in this stone.

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DiamondView Fluorescence Images
Three CVD Synthetic Diamonds Submitted to Mumbai Laboratory

The gemological and spectroscopic characteristics of these type IIa synthetic diamonds suggested that they experienced different growth and/or treatment histories.

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Largest CVD Synthetic Diamond Marquise
Very Large CVD-Grown Synthetic Diamond

The New York laboratory recently tested a 2.16 ct CVD synthetic from Scio Diamond Technology Corp., the largest specimen GIA has seen so far.

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Light Blue Type IIb Diamond
Diamond with Extremely Strong 578.9 nm Emission Center

The outstanding feature of this diamond was the extremely strong emission at 578.9 nm, with possible side bands at 586 and 593 nm.

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Unusual Brown Synthetic CVD Diamond
CVD-Grown Synthetic Diamond with Aggregated Nitrogen Impurities

Recently, an unusual 0.94 ct Fancy yellow-brown emerald cut was submitted to GIA for a synthetic diamond grading report. It contained a cloud of black needle-like inclusions occurring along a plane and showed weak green transmission with fiber-optic illumination.

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146728-SP13-LN
Buff-Top Round Diamond

The New York lab recently examined several diamonds with an interesting variation on the cabochon.

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