Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions
Characterises a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.
Natural-Colour Blue, Grey and Violet Diamonds: Allure of the Deep
Summarises data collected on more than 15,000 natural blue/grey/violet diamonds examined by GIA during the last decade and examines the mechanisms that produce this colour range.
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.
CVD Synthetic Diamonds from Gemesis Corp
An examination of the gemmological and spectroscopic properties of CVD synthetic diamonds from Gemesis Corp.
The “Type” Classification System of Diamonds and Its Importance in Gemmology
Knowledge of type allows gemmologists to better evaluate if a diamond might be treated or synthetic, and whether it should be sent to a laboratory for testing.
The Impact of Internal Whitish And Reflective Graining on the Clarity Grading of D-To-Z Colour Diamonds at the GIA Laboratory
This article reviews the GIA Laboratory’s history of reporting on certain types of graining which are often the only characteristics present in large, high-clarity, high-colour diamonds.
An Examination of Four Important Gems
Several famous and historical gemstones in the Smithsonian's collection are examined and reported on.
GIA’s Symmetry Grading Boundaries for Round Brilliant Cut Diamonds
A presentation of parameters used to support GIA's symmetry grading system.
Colour Grading “D-to-Z” Diamonds at the GIA Laboratory
This article discusses the history and ongoing development of GIA's colour grading system, and explains how its laboratory applies it.