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This is a partial list of the largest non-synthetic diamonds with a rough stone (uncut) weight of over 200 carats (40 grams). [1] The list is not intended to be complete—e.g., the Cullinan (formerly Premier) mine alone has produced 135 diamonds larger than 200 carats since mining commenced.
Through its library and subject experts, GIA acts as a resource of gem and jewelry information for the trade, the public and media outlets. [2] 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]
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]
When designing a diamond cut, two primary factors are considered. Foremost is the refractive index (RI) of a diamond, which, at 2.417 (as measured by sodium light, 589.3 nm), is fairly high compared with that of most other gems. Diamond's RI is responsible for its brilliance—the amount of incident light reflected
Richard T. Liddicoat, Jr. (March 2, 1918 – July 23, 2002) was an American gemologist. An educator in gemology, he contributed in the area of diamond quality grading and gem identification. Liddicoat was the Chairman of the Board of Governors at the Gemological Institute of America (GIA).
These imperfections can confer a yellow, brown, orange, pink, red, or purple colour to the gem. Type IIa diamonds can have their structural deformations "repaired" via a high-pressure, high-temperature process, removing much or all of the diamond's color. [5] Type IIa diamonds constitute a great percentage of Australian production.
It is named after the town of Kimberley in South Africa, where the discovery of an 83.5-carat (16.70 g) diamond called the Star of South Africa in 1869 spawned a diamond rush and led to the excavation of the open-pit mine called the Big Hole. Previously, the term kimberlite has been applied to olivine lamproites as Kimberlite II, however this ...
Printable version; In other projects ... This is a list of countries by diamond production, ... 31.2 Botswana: 25.1: 24.5: 22.9: