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 …

We cover detecting heated corundum, the rare and remarkable Winston Red diamond, and an extraordinary Renaissance jewel containing emeralds from a surprising source.

GIA’s colored diamond color grading terminology uses a combination of fancy grades and color descriptions to locate a diamond’s characteristic color in a region of color space.

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 …

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 …

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.

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 …

This 1925 photo taken at the Green Vaults by Rosch and Krumbhaar shows crown and pavilion views of the Dresden Green, along with a 17-ct drilled briolette-cut colorless diamond and a light blue …

Update of Diamond Type Analysis subject to a fee of 50% of the DTA fee within one year, and thereafter 75% of the DTA fee plus the full Colored Diamond Grading Report Update fee.