The diamond depth percentage is a key measurement used to evaluate the proportions of a diamond. It expresses the depth of the diamond as a percentage of its average diameter (width) and is essential in determining how well the diamond reflects light.
The formula for calculating the depth percentage is:
Depth Percentage=(Average Diameter of the DiamondDepth of the Diamond)×100
Depth Percentage Range:
Ideal Range: For a round brilliant cut diamond, the depth percentage typically falls between 59% and 62.5%. This range provides a good balance between size and brilliance, ensuring that the diamond reflects light well while maintaining an appropriate size.
Shallow Depth: If the depth percentage is below 59%, the diamond may be considered shallow. This can cause light to leak out of the sides, resulting in reduced brilliance and a lackluster appearance.
Too Deep: A depth percentage greater than 62.5% can indicate that the diamond is too deep. This often leads to a smaller appearance for the carat weight, and may also reduce brilliance, as light escapes from the bottom of the diamond.
Ideal Proportions for Round Brilliant Diamonds:
Depth percentage: 59% to 62.5%
Table percentage: 53% to 58% (the percentage of the diamond’s top surface)
When considering diamond depth percentage, it’s important to also take other aspects of the diamond’s proportions into account, like the table percentage, crown angle, and pavilion angle, as they all work together to determine the diamond’s overall appearance and brilliance.