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A diamond's cut is evaluated by trained graders, with higher grades given to stones whose symmetry and proportions most closely match the particular "ideal" used as a benchmark. The strictest standards are applied to the round brilliant; although its facet count is invariable, its proportions are not.
Diamond proportions and facets, for the round brilliant cut. The modern round brilliant-cut was developed by Marcel Tolkowsky in 1919. The ideal proportions are 100% diameter, 53% table, 43.1% pavilion and 16.2% crown. The girdle and culet (if any—not part of Tolkowsky's original design) are cut from the ideal brilliant.
Marcel Tolkowsky (25 December 1899 – 10 February 1991), [1] an engineer by education, was a Belgian member of a Jewish family of diamond cutters from Poland.He is generally acknowledged as the father of the modern round brilliant diamond cut. [2]
In 1919, Lazare Kaplan's cousin, mathematician Marcel Tolkowsky, first published the mathematical formula for diamonds cut to "ideal" proportions, a formula designed to optimise the brilliance, fire and sparkle in a polished diamond. In the same year, LKI became the first commercial-scale operation to cut its diamonds to ideal proportions.
Several different theories on the "ideal" proportions of a diamond have been and continue to be advocated by various owners of patents on machines to view how well a diamond is cut. These advocate a shift away from grading cut by the use of various angles and proportions toward measuring the performance of a cut stone.
Diamond cutting, as well as overall processing, is concentrated in a few cities around the world. The main diamond trading centers are Antwerp, Tel Aviv, and Dubai from where roughs are sent to the main processing centers of India and China. [3] Diamonds are cut and polished in Surat, India and the Chinese cities of Guangzhou and Shenzhen. [4]
HOUSTON (Reuters) -U.S. President-elect Donald Trump plans to make it easier for some producers of liquefied natural gas (LNG) to seek export permit renewals, according to two sources with ...
The diamond cut planning stage is a complex process that requires the cutter to work with unique rough stones. Very often, the location of the inclusions in a rough stone will determine the type of shape to which a diamond may be cut. For economic reasons, most diamonds are cut to retain weight instead of maximizing brilliance. [2]