Inclusion Resembling a Gada in Diamond
Large Stellate Dislocation in Spinel
Rainy Lakeside City in Peridot
A Red Herring in a Red Garnet
Gemological Characteristics of Saltwater Cultured Pearls Produced After Xenotransplantation
X-ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls
The distinction of natural from cultured pearls traditionally has been based on X-radiography.
Color Grading of Colored Diamonds in the GIA Gem Trade Laboratory
HPHT-Processed Diamond Fraudulently Represented as Untreated
An HPHT-treated round brilliant diamond with an inscription that presents as a GIA report number is found to be inconsistent with the institute's report, previously issued for an untreated diamond.
A Useful Technique to Confirm the Hydrophane Nature of Opal
Observing a water drop’s interaction with opal, as well as refractive index, can confirm a specimen’s hydrophane nature with less risk of breakage than total immersion.
Hydrophane Opal Treatment
An opal rough is immersed in water and treated with oil and Opticon to observe effects on transparency and play-of-color.
Identification of “Pistachio” Colored Pearls Treated by Ballerina Pearl Co.
A report on the color treatment process for these intensely greenish yellow to yellowish green cultured pearls and the techniques for identifying them.
Spectral Reflectance and Fluorescence Characteristics of Natural-Color and Heat-Treated “Golden” South Sea Cultured Pearls
A comparison study was made between the yellow and white nacre of the gold-lipped Pinctada maxima oyster shell and 65 yellow cultured pearls.
A Pearl Identification Challenge
Two pearls presented a unique challenge, as testing at three different gemological laboratories could not conclusively identify them as natural or cultured, determine a freshwater or saltwater growth environment, or specify the producing mollusk.
15.53 ct Pearl Discovered in Edible Oyster from the Ostreidae Family
A large natural pearl discovered in an edible oyster offers insight to the scientific pearl community.
“Gran Dama” Brooch Featuring Large Melo Pearl
The centerpiece of this brooch is a 98.67 ct Melo pearl, believed to be one of the world's largest.
Faceting Transparent Rhodonite from Broken Hill, New South Wales, Australia
Transparent rhodonite is considered one of the most difficult of all gems to facet because of its perfect cleavage and brittle, uneven fracture.
The Distinction of Natural from Synthetic Alexandrite by Infrared Spectroscopy
Useful Visual Clue Indicating Corundum Heat Treatment
Shows the conversion of limonitic residues to hematite in surface-reaching inclusions, a practical indication of heat-treated corundum.
The Effects of Heat Treatment on Zircon Inclusions in Madagascar Sapphires
Zircon inclusions in sapphires from Madagascar were studied to investigate the effects of heat treatment on their gemological and spectroscopic features.
Cat's-Eye Demantoid and Brown Andradite with Horsetail Inclusions
The examination of two unusual garnets results in identifications issued for the first time in GIA's colored stone report records.
.jpg "YMAL GIA Ed")
