Diamond is a much more compact form of carbon, with a density of 3.52 g/cm3, 56% higher than the density of graphite. Great confining pressure is required to stabilize the denser configuration of …
Laboratory-Grown Diamond Assessment Criteria As of October 1, 2025, GIA began providing an overall quality evaluation for laboratory-grown diamonds, classifying each stone as either Premium or …
Illustrates the GIA Cut grades and their relative position in the GIA Diamond Cut Grading System. Available for standard round brilliant cut diamonds in the D-to-Z color range and Flawless-to-I clarity …
The 2.33 ct Winston Red diamond (figure 1) is on the verge of becoming one of the most famous fancy-color diamonds in the world. Currently the largest pure red diamond on public display, it is the fifth …
huge rough diamond known as the Cullinan was found a century ago, when the British Empire was at the apex of its power. Its discovery, telegraphed around the world, also brought fame to the then …
The Deepdene diamond (currently 104.53 ct), which was irradiated and heated in 1955 to intensify its yellow hue, is perhaps the most famous treated-color diamond in the world.
Diamond deposits are found in two types of rock: kimberlite and lamproite. Kimberlite—An igneous rock that transports diamonds to the surface. Lamproite—An igneous rock, rarer than kimberlite, that …
Illustrates the GIA Cut grades and their relative position in the GIA Diamond Cut Grading System. Available for standard round brilliant cut diamonds in the D-to-Z color range and Flawless-to-I clarity …
As creator of the 4Cs and the International Diamond Grading System,TM GIA is the global authority and trusted source for unbiased diamond quality assessment. This guide is devoted to helping you …
We cover detecting heated corundum, the rare and remarkable Winston Red diamond, and an extraordinary Renaissance jewel containing emeralds from a surprising source.