Many people think of diamonds as colourless, but in reality colourless diamonds are quite rare. The majority of diamonds in the normal colour range have very faint tints of yellow and brown. Diamonds also occur in a wide range of other colours, including pink, red, blue, green and black. The most intensely coloured diamonds are classified as fancy colours, and fetch very high prices due to their rarity. Diamonds in the normal colour range are graded by their lack of colour; therefore a stone with the highest colour grades has little or no visible colouration. Colour grades can cause dramatic variations in price, although distinguishing between the top colour grades in smaller mounted stones is almost impossible to the untrained eye. The colour of diamonds is designated using the following grading scale: D E F G H I J K L M N-Z Colourless   Nearly colourless Slightly tinted  Tinted Each grade represents a spread or range of colour, not just one point along the series. In this range, a D colour diamond will always be the most valuable if all the other factors of clarity, carat and cut are equal.