The Wittelsbach Blue
This article describes what is known about the Wittelsbach Blue since it was first reported in 1666, and the gemmological information released to date on this diamond.
Grey-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 coloured grey to blue to violet.
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.
Characterisation and Grading of Natural-Colour Pink Diamonds
Known for their great beauty and rarity, pink diamonds have long been sought after by jewellers, collectors and consumers.
Grading the Hope Diamond
One of the most popular exhibits at the Smithsonian Institution, the stunning Fancy Dark greyish blue Hope diamond was formally graded by GIA’s gem laboratory.
The French Blue and the Hope: New Data from the Discovery of a Historical Lead Cast
With the use of modern tools and technology, this article sheds light on the history and provenance of both the French Blue and the Hope diamonds.
Colour Grading of Coloured Diamonds in the GIA Gem Trade Laboratory
How GIA’s Gem Trade Laboratory grades coloured diamonds, including an expanded colour grading terminology, is explained.
Characterisation and Grading of Natural-Colour Yellow Diamonds
A large number of natural-colour yellow diamonds are analysed using grading and appearance aspects among other characteristics to clarify the differences between them and the light yellow diamonds associated with GIA's D-to-Z colour grading scale.
Characterising Natural-Colour Type IIB Blue Diamonds
More than 400 blue diamonds were studied at the GIA Gem Trade Laboratory over several years to reveal additional information about the relationships between their colour, clarity and other gemmological properties.
An Important Exhibition of Seven Rare Gem Diamonds
The stories behind seven strikingly beautiful rare natural diamonds, united in an exhibit at the Smithsonian, are told here.