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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 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]
IGI provides independent grading reports, colored stone reports, identification and appraisal reports, diamond authentication and attestations of origin, and laser inscription services. They also offers diamond and colored stone courses through IGI's Schools of Gemology. [ 7 ]
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
The GIA began grading cut on every grading report for round brilliant beginning in 2006 [34] based on their comprehensive study of 20,000 proportions with 70,000 observations of 2,000 diamonds. [citation needed] The single descriptive words are as follows: Excellent, Very Good, Good, Fair, and Poor. [33]
Ironically, in 1997, a seminal study by the Gemological Institute of America (GIA) concluded that, "in general, the strength of fluorescence had no widely perceptible effect on the color appearance of diamonds viewed table-down (as is typical in laboratory and trade grading). In the table-up position (as is commonly encountered in jewellery ...
The diamonds sold at Worthy.com are graded at the Gemological Institute of America (GIA) or at the International Gemology Institute (IGI). The brand-named watches are authenticated at CentralWatch. Prior to auction, Worthy.com makes available the item's photographs and diamond grading report to the networks of pre-selected professional buyers.
Grading standards have changed over the years. Because collectors and dealers have gotten more selective, an informal "sub-grade" system has evolved. "A" coins are the best of the grade, "B" coins are "solid", and "C" coins are at the low end of a particular grade based on the Sheldon scale, e.g., MS-65. CAC stickers are intended to standardize ...