is the ratio of the total depth of the diamond (from table to culet) as compared with the total diameter (which is used as the 100% figure for all diamond dimensions). For instance, if the total diameter of a round diamond is 6.00 mm and the total depth is 4.00 mm, then the depth percentage is 66.7%.

Ideal = 58 - 60%
Excellent = 60.1 - 62%
Good = 62 - 64%
Fair = 64 - 66%
Poor = over 66% or under 57%