Diamond color actually means a lack of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. GIA’s D-to-Z diamond color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones or stones of established color value.

GIA’s diamond D-to-Z color-grading scale is the industry’s most widely accepted grading system. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Many of these color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.

Fun fact: Color is the only factor that is not determined by examining the table or a top-down perspective. Diamonds are actually graded for color by placing them upside down (with the table resting on the surface) on a pure white piece of paper.