A diamond's color has a significant impact on its appearance. With its many prismatic facets, a colorless diamond reflects light into a spectrum of hues, a characteristic often referred to as "fire". The presence of noticeable color in a diamond may reduce its ability to reflect light. Consequently, diamonds with lower color grades will not show the same luminosity and fire as those with higher grades. The most valuable diamonds have little to no detectable color.
The diamond color scale begins at D (colorless) and ends at Z (light yellow). Diamond color is often difficult to discern when a diamond is viewed face up. Therefore, gemologists typically evaluate diamonds facedown against a pure white surface, illuminated by carefully controlled lighting. The diamond is then compared to master stones of predetermined color.
Highest-quality color grade a diamond can receive. A D-color diamond is extremely rare and emits unrivaled brilliance.
Contains very minute traces of color. Also a rarity, an E-color rated diamond emits a high level of brilliance and sparkle.
Minute traces of color can only be detected by a trained gemologist. This is a high-quality color grade.
Contains noticeable color only when compared to higher color grades. Appearing colorless to the untrained eye, a G or H color diamond provides an excellent value.
Contains slightly detectable color. An I-color or J-color diamond is an excellent value, as it typically appears colorless to the untrained eye.
Faint color is noticeable. Even with the presence of color, these grades of diamonds can emit fire and beauty.
Diamonds that exhibit a color other than light yellow or brown, as well as diamonds that possess a more intense yellow or brown than the 'Z' color rating, are considered "fancy colored". With only one out of ten thousand diamonds possessing a natural color, these types of stones are extremely rare. Depending on the coloration, intensity, and hue of a diamond, color can either detract or enhance its value. Naturally occurring diamond colors include gray, white, blue, yellow, orange, red, green, olive, pink, purple, brown, and black. Red stones are the most rare of the fancy colored diamonds.
Similar to the process for grading colorless diamonds, a diamond's fancy color is graded by comparing it to master stones of predetermined color. Unlike colorless diamonds, fancy colored diamonds are graded face up. The most important factors in determining the value of a naturally colored diamond is the strength of its color. The value of a fancy colored diamond increases with the intensity of the most prominent hue within the stone.