Spring 1991 G&G Lab Notes
This section, from the Spring 1991 issue of Gems & Gemmology, is a compilation of interesting finds from GIA’s laboratories.
Large HPHT-Treated Fancy Pink Diamond
The New York lab encountered another large HPHT-treated diamond that showed stronger pink colouration.
Diamond with High Concentration of Nickel
Analysis of Fancy Light greenish yellow diamond leads to detection of nickel, as well as an inclusion that gives a colour-change effect.
Green Diamond Treated with Radioactive Salt
The stone owes all of its green colour to these shallow radiation stains.
Orange Diamond with Unusual Colour Origin
GIA recently examined a rare orange diamond that demonstrated the complexity of diamond colour origin.
Diamond, Artificially Irradiated and Coated Brown
Examination of a diamond with a rare and highly sought-after Fancy reddish brown colour revealed that it had been irradiated and coated.
Black diamond with unusual colour origin
This black diamond's colour was produced by natural radiation stains, an unusual cause of colour.
Two Fancy Dark Grey CVD Synthetic Diamonds
Examination of two CVD synthetic diamonds with an unusual Fancy Dark grey colour.
Spring 2015 G&G Examines Blue Spinel, Chinese Jewellery Design and the Latest in Synthetics
G&G Brief presents an overview of the content of the Spring 2015 issue of Gems & Gemology.