The GIA Gem Trade Laboratory (GIA-GTL) operated by the Gemological Institute of America does not issue a proportions grade for the diamonds that they evaluate, nor do they provide complete proportions information on their diamond grading reports. However it is possible to have an ideal cut diamond graded by the GIA and they are quite common in the market. In order to determine whether a GIA graded diamond is ideal cut, the crown angle and pavilion angle measurements must be determined. The crown angle and pavilion angle measurements are not provided on the GIA diamond grading report. The most accurate way to determine the crown angle and pavilion angle measurement is to measure the diamond using Sarin or OGI Technology. Both Sarin and OGI machines take approximately 40 measurements, eight per section of the diamond, and then average the results. Many of the machines will produce a label based on the proportions guidelines set forth by the American Gem Society Laboratory for ideal cut diamonds. In addition to the proportions, we require that the polish and symmetry of our GIA graded ideal cut diamonds be excellent... All of the GIA Graded Ideal Cut Diamonds listed for sale in our Private Reserve are accompanied by Sarin results showing the proportions of the diamond.
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GIA Graded Ideal Cut Diamonds
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