Colour plays a major role in determining the quality of a diamond. A diamond acts as a prism, dividing the light into a spectrum of colours and dispersing this light as colourful flashes called Fire.
White diamonds, although they appear colourless, can have tinges of yellow and brown. As these tones become more easily apparent, the rarity and value of the diamond decreases. D is the highest grade & indicates a completely colourless diamond.
Strong coloured diamonds called Fancies have colours ranging from intense yellow through to blue, green, pink & red. These diamonds are extremely rare & valuable.