The width of the Table Facet, divided by the average diameter of the diamond. For example, an ideal table percentage for a Round Brilliant Cutmight be around 53% to 58%. Some older dealers (perhaps my age after 30 years in this business) still like and promote the 60/60 Cut, which refers to a diamond with a 60% table percentage and a 60% Depth %. All such Proportions are factors in determining the overall Light Performance, beauty, and value of a diamond.