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 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.
Lab-Grown Coloured Diamonds from Chatham Created Gems
This article compares some of Chatham Created Gems’ synthetic coloured diamonds to natural diamonds and explains the results.
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.
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.
Identification of HPHT-Treated Yellow to Green Diamonds
Greenish yellow to yellowish green HPHT-treated diamonds exhibited highly saturated body colour, well-defined brown to yellow octahedral graining and visual evidence of heating, among other characteristics.
Natural-Colour Nonconductive Grey-to-Blue Diamonds
Two new categories of grey-to-blue diamonds are described.
Contribution to the Identification of Treated Coloured Diamonds: Diamonds with Peculiar Colour-Zoned Pavilions
Some treated yellow and blue-to-green diamonds show a peculiar colour zoning when viewed through the pavilion.
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.
Three Notable Fancy-Colour Diamonds: Purplish Red, Purple-Pink and Reddish Purple
The description and properties of three fancy-colour diamonds auctioned at Christie's.