Orange Diamond with Unusual Color Origin
GIA recently examined a rare orange diamond that demonstrated the complexity of diamond color origin.
Large HPHT-Treated Fancy Pink Diamond
The New York lab encountered another large HPHT-treated diamond that showed stronger pink coloration.
Pseudo-Synthetic Growth Structure Observed in Natural Diamond
This stone was a good example of a very rare natural diamond exhibiting synthetic growth characteristics.
Green Diamond Treated with Radioactive Salt
The stone owes all of its green color to these shallow radiation stains.
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.
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.
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.
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.
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.
Buff-Top Round Diamond
The New York lab recently examined several diamonds with an interesting variation on the cabochon.