Unlike colorless and near-colorless diamonds, fancy-color diamonds are evaluated less for brilliance or fire and more for color intensity. Shades that are deep and distinct are rated higher than weak or pale shades.
GIA describes color in terms of hue, tone and saturation. Hue refers to the diamond's characteristic color, tone refers to the color's relative lightness or darkness and saturation refers the color's depth or strength. Using highly controlled viewing conditions and color comparators, a fancy color grader selects one of 27 hues, then describes tone and saturation with terms such as "Fancy Light," "Fancy Intense," and "Fancy Vivid." The color system GIA developed is used worldwide.