A diamond's color refers to the amount of color the diamond contains, the presence or absence of color in white diamonds. Colorless diamonds are the most desirable since they allow the most refraction of light and thus to sparkle the most off-white diamonds absorb light, inhibiting brilliance.

The color scale begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with very faint or light yellowish or brownish color. The color scale continues all the way to Z. Colors can also range from intense yellow to brown, blue, green, pink and red. These fancy colors are rare and therefore more valuable.