A colourless or "white" diamond is more sought after and more valuable than one with slight tinges of yellow colour. These tinges can be seen due to the presence of other elements within the diamond and can sometimes not even be
seen with the naked eye. With 23 colour grades being recognised by the major international diamond grading laboratories, the colour can vary greatly, and only 3 of those are classified as colourless. The further towards colourless
the diamond is, the rarer it becomes.
There are also diamonds with a strong, pure colour such as orange, green, yellow, pink and blue. These are called "fancy" diamonds and are also extremely rare and valuable.