(a The colour of colourless diamonds can go from D (colourless) to Z (light yellow). Less than 1% of the diamonds are colourless, which make them very rare. As one would predict, a truly colourless stone will carry a premium price.
(b) Besides colourless diamonds, there are also ‘fancy colours’ of which the colour shade can vary from faint to intense. Natural fancy diamonds are very exclusive and rare, even rarer than colourless diamonds. A true natural colour diamond has been gifted to us by nature and can be found in a variety of colours, from pink to yellow to brown and even red. Fancy coloured diamonds are only to be found in very limited areas. The cause for the colour in coloured diamonds varies from colour to colour. For instance, yellow diamonds owe their cheerful hue to the presence of nitrogen. Blue diamonds, on the other hand, contain boron, which causes a blue colour. The cause of pink and red diamonds' remarkable colour is unknown for certain, though speculations state that they are variations of the result of fractures in the crystal lattice. The rarer the colour, and the more intensely the colour shows, the higher the value. Yellow and brown diamonds are most commonly found, while red, blue, and green diamonds are among the rarest of all fancy colours. Similarly, diamonds with lighter colour intensity levels such as faint, very light, light, fancy light, and fancy are more common than diamonds with the richer intensities of fancy intense, fancy vivid, and fancy deep, and thus less in value.