PRECIOUS METAL GRADINGSParts per thousand indicating the fineness of the metal are referred to as the Standard Mark. For example .925 silver denotes that the item of jewellery is made from 92.5% silver. The remaining 7.5% typically includes copper and zinc which is combined with the pure silver. Maker's Mark % Platinum % Silver % Palladium % Gold & Colour AssayIn the UK most gold jewellery is either 9 carat ('9K') or 18K. In Europe and the USA 14K is more prevalent. The four main UK assay offices are responsible for standardizing the metal gradings by evaluating compliance. There are also assay sub-offices which are permitted to mark their own jewellery with the permission and under the monitoring of one of the main assay offices.