There is no such thing as best colour for diamonds in terms of an individual preference; however, in terms of quality and value the best colour is no colour at all because such a diamond is extremely rare and would be designated a D colour, under the GIA grading system. It is important to remember, however, that many customers actually prefer a hint of colour, or even a pronounced colour which in diamonds often means what is termed a “fancy coloured diamond”.
The rarest and most valuable diamonds in the world are those that come closest to having no colour at all other than the very rare diamonds called “fancies” such as blue, red, or green, pink or intense yellow. However, colour is only one of the four criteria by which a diamond will be judged. Equally important are cut, clarity and carat weight. So the closer a diamond is to flawless and without colour the rarer and more valuable it will be.
Diamonds that have no colour at all are extremely rare and therefore more valuable than those that are tinted white.
There are a number of internationally recognized grading scales, all of which will enable you to judge the quality and value of your diamond. These scales are by an large compatible but may well use different nomenclature. G is a description most commonly used by the laboratories and you should consult your jeweller on how other scales express the identical grade.