How do experts assess a diamond’s color? Although many diamonds appear colorless, GIA gemologists can detect even the slightest presence of yellow or other hues. GIA established the color grading standard, called the GIA Color Scale, to indicate the absence or presence of color. The scale begins with the letter D, representing colorlessness, and continues with the increasing presence of color to the letter Z. Diamond graders use color-comparison diamonds, called masterstones, to determine a diam

DIAMOND COLORThe color evaluation of most gem-quality diamonds is based on the absence 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 color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.GIA's D-to-Z color-grading scale is the industry's most widely accepted grading system.