Identification of “Pistachio” Coloured Pearls Treated by Ballerina Pearl Co.
A report on the colour treatment process for these intensely greenish yellow to yellowish-green cultured pearls and the techniques for identifying them.
Variscite from Central Tajikistan: Preliminary Results
A look at the gemmological properties and chemical composition of this light blue to light green to green gem material, which is suitable for cabochon cutting.
Observations on CVD-Grown Synthetic Diamonds: A Review
Explores statistical data and defining characteristics of gem-quality CVD synthetic diamonds examined by GIA since 2003.
An Introduction to Photoluminescence Spectroscopy for Diamond and Its Applications in Gemmology
Presents the underlying physics and methodology of this analytical technique, which has become an essential tool in identifying treated and synthetic diamonds.
Why are Pink Diamonds Pink? GIA Researchers Dive Deep into their Crystal Structure
GIA researchers analysed more than 90,000 natural pink diamonds to better understand how these rare and beautiful diamonds formed and got their colour.
True Colours of “Dalmatian Jasper”
Discusses the mineralogical composition and provenance of this spotted decorative gemstone.
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany
Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s until the 1970s.
Photoluminescence Spectra of Emeralds from Colombia, Afghanistan and Zambia
Compares PL spectroscopy data of 48 emerald samples from three countries to evaluate the usefulness of the technique in geographic origin determination.
Observations on HPHT-Grown Synthetic Diamonds: A Review
Summarises statistical data and distinctive features of several thousand gem-quality HPHT synthetic diamonds examined by GIA from 2007 through 2016.
Saltwater Pearls from the Pre- to Early Columbian Era: A Gemmological and Radiocarbon Dating Study
Examines 85 saltwater natural pearls, reportedly harvested from the Caribbean islands off the coast of Venezuela during the early 16th century, to determine their age.