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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
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.
If two diamonds of equal weight are inspected there can be a noticeable difference in size when viewed from above; arguably the most important view. A well-cut 0.90ct diamond, for example, could have the same width as a poorly cut 1.00ct diamond. This phenomenon is known as spread. Cut also affects the color of a diamond.
In 1953, Liddicoat introduced the GIA diamond grading system - a practical approach to grading the quality of colorless to light yellow polished diamonds on the basis of color, clarity, and cut. A central feature was the D-to-Z color grading system for faceted colorless to light yellow diamonds—the vast majority of diamonds seen in the trade.
The 2005 AGS standards penalize stones with "cheated" girdles. They grade from 0 to 10. The GIA began grading cut on every grading report beginning in 2006, based on their comprehensive study of 20,000 proportions with 70,000 observations of 2,000 diamonds. [11] The single descriptive words are as follows: Excellent, Very Good, Good, Fair, and ...
The subsequent FTC restrictions undoubtedly encouraged the establishment of today's GIA color grading system. The new GIA grading system had no place for the effect of fluorescence on color and the desirability of fluorescence in a diamond began to wane in the years that followed. Diamonds with fluorescence were marked down in price.
There are numerous diamond grading laboratories, with each offering investors, consumers and dealers similar diamond-grading and verification services, including the Gemological Institute of America (GIA) and the CIBJO (Confédération Internationale de la Bijouterie, Joaillerie et Orfèvrerie), also known as the World Jewellery Confederation.