The diamond colour grading scale varies from totally colourless to light yellow. The differences between one diamond colour grade and another are very subtle and difficult to distinguish.

D-F: Absolutely colourless. The highest colour grade, which is extremely rare. G-J: Near colourless: good to very good colour, and this diamond may "face up" colourless when mounted, especially in white gold or platinum. K-M: Light but noticeable yellow or brown tint. Not recommended for larger diamond stone purchases, especially in engagement rings. Out of the 4 C's, colour and cut are the two most important characteristics of a diamond. Do not compromise on colour. An "H" colour or better is usually best.