Only one quarter of all diamonds meet the high quality standards required for jewellery. Of these, only a small percentage fulfill all the parameters which apply to precious stones today - namely correct size; suitable shape; high clarity; no faults; cutting quality; brilliance; colour dispersion; hardness; rarity and, depending on the customer’s wishes, colour or transparency. The criteria used to judge the quality, and thus price, of a cut diamond are known as the ‘Four C’s’: Carat, Colour, Clarity and Cut.