Discussion of a white diamond's color may seem counter-intuitive at first because the most desired color in white diamonds is, in fact, no color. Color is judged by how far the diamond deviates from pure white and, generally, lower quality diamonds are those with yellowish or brownish tints. The best way to see a diamond's color is to look at it against a white surface. However, color grades are so subtle, it is often difficult to distinguish the difference with the naked eye. Gemologists grade the color of a diamond by comparing it to a master set of diamonds. The master set is a collection of carefully graded diamonds chosen for their color accuracy so they can be used in the color grading of other diamonds.
Few diamonds are totally colorless, but the less color that is present in the diamond, the more rare the diamond and the greater its value. Because of the molecular structure of a diamond, its color will never change over time.
Letters are used to grade the color of white diamonds. The highest grade of white diamonds is D, the most rare and the most costly, and progresses down the alphabet for lower qualities. Even though color grades D through F are at the top of the list, you can find beautiful diamonds that are graded near colorless in grades from G through J. Here is what the grades mean:
Grades D-F: in colorless range:
D Colorless: no color whatsoever
E Colorless: only minute traces of color that cannot be seen by the untrained eye
F Colorless: slight color that can be detected by a sophisticated eye, considered colorless.
Grades G-H: Near colorless, each having a slight tint of color, increasing as they progress down the alphabet
Grades H-J: Near colorless, but slight tints noticeable when compared with higher-grade diamonds
Grades I-J: Near colorless, but color is slightly detectable
Diamonds are graded by the alphabet until they concentrate so much color as to become fancy colors, which make them more valuable for their color depth. Colored diamonds occur in canary yellow, pink, red, violet, blue, orange, red and green. Depending on their color intensity, they may be extremely expensive.
Colored diamonds intensity of color is graded into the following categories: Light Fancy; Fancy; Fancy Intense; Fancy Vivid; and Fancy Deep