Learn how proportions are calculated:
The average diameter of a round brilliant cut diamond would be calculated by obtaining the minimum and maximum diameters and dividing their total by two.
For example:
minimum diameter 6.09
maximum diameter 6.15
The average diameter equals =
6.09 + 6.15 =12.24
12.24 / 2 = 6.12
The table percentage is calculated by determining the average table diameter and dividing it by the diamonds average girdle diameter. Convert the result to percentage ((mulitiply by 100). Round to the nearest one percent.
For example:
average table diameter 3.67 millimeters
average girdle diameter 6.12 millimeters
The table percentage equals =
(3.67 / 6.12) =.59967
.59967 x 100 = 59.96%
rounded to 60%
The total depth percentage, pavilion depth percentage and crown height percentage is calculated by dividing average measurement of each by average girdle diameter. Convert the result to percentage (multiply by 100). Round to the nearest .01% percent.