After cut, color is generally considered to be the most important characteristic of a diamond — mainly because the human eye tends to detect a diamond’s sparkle first and color second. Color manifests itself in a diamond as pale yellow, so a diamond’s true color grade is based on its lack of color. The less color a diamond has, the higher its color grade. A color grade of D is the highest possible, with Z being the lowest.
• J-I: Near colorless; slightly detectable warmth or tone
• H-G: Near colorless; color is difficult to detect unless compared side-by-side against diamonds of better grades
• F-E: Colorless; minute traces of color can be detected by an expert gemologist
• D: Absolutely colorless; the highest color grade possible.