Johnson Matthey has over 150 years experience supplying jewellery manufacturers and craftsmen with platinum and platinum alloys of guaranteed quality, and refining their scrap materials.

Johnson Matthey has a range of platinum alloys that enable easy processing from casting to final polishing. Choosing a suitable alloy depends on the market into which it is to be sold and the method used to make the jewellery. For example items suitable for sale in Japan or Germany may not meet the standards of fineness required for hallmarking by the UK assay offices, or by the USA to be sold as "platinum."

There are some general purpose platinum alloys, but it is best to select one that is suited to casting, handworking or automated production, depending on which is predominant in fabricating the piece. Even a 5% alloy addition can harden or improve castability of platinum, but there is considerably more scope if regulations allow greater additions, even if part of that must be platinum group metals.

Applications/Notes
Fluid for hard castings