Masterstones define color grades in which range?

• A. D-to-Z.
• B. A-to-G.
• C. C-to-M.
• D. E-to-I.

Answer: (A)

Masterstones define the color grading range used for diamonds from D to Z. In color grading, stones are compared to a set of reference stones to place them on a scale that starts with D (colorless) and ends at Z (pronounced color). This full D-to-Z range covers the entire spectrum that graders encounter, from truly colorless to strongly colored stones. The other ranges don’t align with the established system used for calibration and documentation, because they either omit portions of the scale or use nonstandard lettering. So the masterstones are specifically defined to span D to Z, providing the authoritative reference for color evaluation.