Colorless is the top range of the D-to-Z scale: the grades D, E and F.
In more detail
These are the rarest grades. Even a trained grader can tell them apart only beside master stones.
On a grading report
Shown by the color letter; IGI names its bands on the report.
Related terms
- Color grade: The color grade is a letter from D to Z for the yellow or brown tint of a near-colorless diamond. D is colorless and Z is light yellow or brown.
- Near colorless (G–J): Near colorless is the D-to-Z range from G to J.
- Master stones: Master stones are reference diamonds of known color grade. A grader sets a diamond beside them to decide its D-to-Z letter.