Total Depth Percentage is defined as which measurement?

• A. Table-to-culet depth, expressed as a percentage of average girdle diameter.
• B. Crown height as a percentage of total depth.
• C. Culet size relative to girdle diameter.
• D. Table size as a percentage of girdle diameter.

Answer: (A)

Total Depth Percentage measures how deep a diamond is in relation to its width, defined as the distance from the table to the culet expressed as a percentage of the average girdle diameter. This reflects the table-to-crystal depth along the diamond’s central axis divided by the girdle width, giving a single number that describes overall depth. The concept matters because depth influences how light interacts inside the diamond and thus its brilliance and fire; too deep or too shallow can mute sparkle, while a balanced depth contributes to a pleasing, well-proportioned look. For example, if the overall distance from the table to the culet is 12.5 mm and the average girdle diameter is 19.0 mm, the total depth percentage would be about 66%. Other measurements describe different relationships: crown height as a percentage of total depth looks at the height of the crown portion relative to the full depth; culet size relative to girdle diameter compares the culet width to the girdle; table size as a percentage of girdle diameter compares the table width to the girdle width.