A diamond's colour is one of the most important factors in determining its value. The nearer a white diamond is to being absolutely colourless, the more rare and valuable it is. The graduations in colour are so subtle that intricate international grading scales have been devised. Diamonds are graded into categories defined by letters. Colours range from exceptional
whites (categories D, E and F) to tinted colours (categories M to Z). The best way to pinpoint a diamond's true colour is to place it next to another diamond that has previously been graded. There are also fancy coloured diamonds (PINK, CHAMPAGNE, GREEN , BLUE , YELLOW ) which are graded according to their intensity of colour, not lack of it.