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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]
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.
Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate. As the diamond trade developed, early diamond grades were introduced. Without any co-operative development, these early grading systems lacked standard nomenclature and consistency. Some early grading scales were; I, II, III; A, AA, AAA; A, B, C. Numerous terms
Synthetic diamonds of various colors grown by the high-pressure and high-temperature technique, the diamond size is ~2 mm. Infrared absorption spectrum of type IaB diamond. (1) region of nitrogen impurities absorption (here mostly due to the B-centers), (2) platelets peak, (3) self-absorption of diamond lattice, (4) hydrogen peaks at 3107 and ...
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.
The short B-N (1.57 Å) bond is close to the diamond C-C bond length (1.54 Å), that results in strong covalent bonding between atoms in the same fashion as in diamond. The slight decrease in covalency for B-N bonds compared to C-C bonds reduces the hardness from ~100 GPa for diamond down to 48 GPa in c-BN.
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