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Diamond certified FL (flawless) by the GIA Two diamonds of grade VS 1 and SI 2 respectively. The GIA diamond grading scale is divided into six categories and eleven grades. [2] The clarity categories and grades are: [3] Flawless category (FL) diamonds have no inclusions or blemishes visible under 10× magnification. [3]
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In 1953 the GIA developed its International Diamond Grading System and the "four Cs" (cut, clarity, color, and carat weight) as a standard to compare and evaluate the quality of diamonds. [2] As of 2024, the institute is headquartered in Carlsbad, California, and operates in 13 countries, with 11 campuses, 9 laboratories, and 4 research centers.
Diamond World News Service. June 7, 2008 "Diamond Certificates And Its Importance In The Industry". April 19, 2022; Simon, Bernard (June 27, 2002). "Adding Brand Names To Nameless Stones". Diamond New York Times "International Gemological Institute". Europa Star. April 1, 2002
Type II diamonds have very few if any nitrogen impurities. Pure (type IIa) diamond can be colored pink, red, or, brown owing to structural anomalies arising through plastic deformation during crystal growth; [20] these diamonds are rare (1.8% of gem diamonds), but constitute a large percentage of Australian diamonds. Type IIb diamonds, which ...
Lonsdaleite (named in honour of Kathleen Lonsdale), also called hexagonal diamond in reference to the crystal structure, is an allotrope of carbon with a hexagonal lattice, as opposed to the cubical lattice of conventional diamond.
Most Ia diamonds are a mixture of IaA and IaB material; these diamonds belong to the Cape series, named after the diamond-rich region formerly known as Cape Province in South Africa, whose deposits are largely Type Ia. Type Ia diamonds often show sharp absorption bands with the main band at 415.5 nm (N3) and weaker lines at 478 nm (N2), 465 nm ...
It is unclear whether the synthesis products are diamond-like solid solutions between carbon and boron nitride or just mechanical mixtures of highly dispersed diamond and c-BN. In 2001, a diamond-like-structured c-BC 2 N was synthesized at pressures >18 GPa and temperatures >2,200 K by a direct solid-state phase transition of graphite-like (BN ...