Diamond Cut GradingA rough diamond looks like any other rock until it is "cut" into many facets at optimum angles to produce maximum brilliance (sparkle) and fire (reflected colors). The quality of the cut is known as the "make".
In 1919 Marcel Tolkowsky developed the formula for the round brilliant cut which has become the standard or "ideal" cut for diamonds. Since then there have been various modifications and disagreement over what constitutes the true "ideal" cut. However, the Gemological Institute of America (GIA) has developed guidelines for grading the make of round brilliant cut diamonds only.
The first two factors are the most important, and only round brilliant cut diamonds can be rated as Class 1. The term, "ideal cut", is no longer used by the GIA, but is still used by most of the diamond industry.
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