Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions
Characterizes a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.
Natural-Color Blue, Gray, and Violet Diamonds: Allure of the Deep
Summarizes data collected on more than 15,000 natural blue/gray/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this color range.
Grading the Hope Diamond
One of the most popular exhibits at the Smithsonian Institution, the stunning Fancy Dark grayish blue Hope diamond was formally graded by GIA’s gem laboratory.
Natural-Color Green Diamonds: A Beautiful Conundrum
Characterizes diamonds with exceptionally rare natural green color, based on GIA’s extensive database of samples.
Saltwater Pearls from the Pre- to Early Columbian Era: A Gemological 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.
The Wittelsbach Blue
This article describes what is known about the Wittelsbach Blue since it was first reported in 1666, and the gemological information released to date on this diamond.
Developments in Gemstone Analysis Techniques and Instrumentation During the 2000s
The first decade of the 2000s continued the trend of using more powerful analytical instruments to solve gem identification problems.
Gray-To-Blue-To-Violet Hydrogen-Rich Diamonds from the Argyle Mine, Australia
The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds colored gray to blue to violet.
Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds
A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.
A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds
The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish, and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.