Most of the world’s diamonds are graded on a scale of colorless to light yellow or light brown.In diamonds, "color" refers to the absence of color within the stone.Most diamonds naturally have slight traces of yellow or brown, but the less color a diamond has, the more desirable and valuable it is (for white diamonds, at least).The rarest and most expensive are diamonds in the colorless range graded D,E and F on a scale that descends to Z. Diamonds with more color than Z, or in other shades such as orange, pink, blue, etc. are classified as “Fancy Colored Diamonds”