DEPTH

A diamond’s depth is measured from the table (the flat facet at the top of a
diamond), to the culet (the point at the base of a cut diamond). Depth percentage 
is crucial, as this denotes the proportions of the diamond and will affect the
brilliance, fire and scintillation, and therefore the superiority of the cut. Cut too
shallow and light will be lost without reflection, cut too deep and the stone loses
sparkle.