Coloured diamonds are graded on the intensity of their colour, as opposed to lack of it. They are graded within a different system and do not follow the rules for white diamonds.
The most common coloured diamonds are yellow and brown (champagne and cognac), followed by pink and blue. Green, red, purple and orange are the rarest of coloured diamonds. Diamonds sold for their colour are labelled as “fancy” diamonds and some can rival exceptional white diamonds in cost.