Although a diamond may be any color of the spectrum, grading a cut stone for color means deciding the amount by which it deviates from the whitest possible (truly colorless). Completely colorless, icy-white diamonds are rare, and therefore, more valuable.

The best way to see the true color of a diamond is looking at it against a white surface. Although most diamonds are a shade of white, they do come in all colors - pale yellow, canary, pink, red, green, blue and brown. These are called "fancies," and they are valued for their depth of color, just as white diamonds are valued for their lack of color. The famous Hope Diamond is blue, and the well-known Tiffany Diamond is canary.
