Color usually refers to the presence or absence of color in white diamonds. It never changes over time. Because a colorless diamond, like a clear window, allows more light to pass through it than a colored diamond, colorless diamonds emit more sparkle and fire. The whiter a diamond's color, the greater its value. Fancy color diamonds do not follow this rule. These diamonds, which are very rare and very expensive, can be any color from blue to green to bright yellow.

Most jewelers refer to GIA's professional color scale that begins with the highest rating of D for colorless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish color. The color scale continues all the way to Z. Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colorless. And diamonds graded G through J show virtually no color that is visible to the untrained eye.