The color evaluation of most gem-quality diamonds is based on the absence of color. A pure and structurally perfect diamond has no hue, like a drop of water, and therefore, a higher value. We have GIA’s certified D-to-Z color-grading system, measuring the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.
The GIA 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.