Cut Grade (5.42)
GIA first started issuing diamond grading reports with cut grade valuation in January of 2006 for the round brilliant only. Their 15 year quest to find the optimal cut specifications started in 1989 when research developed an advanced ray-tracing program along with computer program modeling at the same time which helped GIA researchers analyze how light behaves within a diamond and its affect on appearance.
GIA eventually realized the computer generated models were not enough to determine maximum brilliance, (brightness, dispersion, and scintillation acting together in the face-up position), for the round brilliant. The next step was to approach human observers including manufacturers, wholesalers, retailers, and the typical consumer, choosing different environmental conditions such as retail settings or in a room that was typical of everyday life. Of course polish and symmetry indirectly affected the the final evaluations also.
