The best colour for a diamond is no colour at all. These are known as ‘white diamonds’. Other rare diamonds with a pure colour, such as pinks, blues or greens, are also valuable and are known as ‘Fancies’. Colour grading scales from colourless to light yellow. The differences from one grade to another are very subtle, evidenced by the number of grades within each category shown on the International Colour Grading Systems Chart. Diamonds range from colourless - the rarest and most valuable - to yellowish, with a spectrum of shading in between.