Natural diamonds appear more or less in all possible colour hues. The relatively small number of jewellery diamonds may be classified colour-wise in two groups:
1) Absolutely colourless to light yellow or light brown diamonds in the so-called regular colour range.
2) Diamonds in all other colours which are suitable for jewellery purposes.
In the case of coloured diamonds, the grader must also examine whether the colour has its origin from natural crystallization conditions or if one of the different treatment methods had been used.