The average diameter of a round is the mean of its minimum and maximum diameters, measured across the girdle.
In more detail
It is the base for the percentages on a report. Table, crown height, girdle, pavilion depth and total depth are all shares of it.
On a grading report
Not printed as its own line: average the first two numbers of the measurements line.
Related terms
- Measurements: Measurements is the report line that gives a stone's size in millimeters. A round reads minimum – maximum diameter × depth, and a fancy shape length × width × depth.
- Total depth: Total depth is the height of a stone from table to culet as a percentage of its average diameter. It equals crown height + girdle thickness + pavilion depth.
- Table size: Table size is the width of the table as a percentage of the average diameter.
- Proportions: A diamond's proportions are the angles and percentages that describe its shape in profile. They cover the table, crown, pavilion, star and lower half lengths, girdle, culet and total depth.