Johnson Matthey began researching platinum jewellery alloys in the mid 1970’s for manufacturers who had difficulties with palladium/platinum alloys and couldn’t meet rapidly growing consumer demand in Japan.

Platinum/copper alloys were being commonly used in Europe for hand manufacturing jewelry at that time but research determined their casting properties were poor. Platinum/cobalt, however, was discovered to have definite advantages for casting and began to find popularity in Europe and Japan for this application.

Machining of platinum has always presented problems, particularly with respect to finish and tool-wear. Research identified new materials (e.g. PCD), ideal tool angles, improved processes (lubrication flow and surface speed), as well as the platinum alloy that offered the best machining properties – platinum/ruthenium.

Today in the USA, these alloys, along with platinum/iridium (used by US jewellery manufacturers since the 1920’s) form the backbone of the materials used in the manufacture of platinum jewellery. But in addition to these Johnson Matthey looked at a wide range of other alloy systems that today have been used as the basis for a considerable amount of research by other bullion companies. These alloys include: platinum/gallium/indium and platinum/gallium alloys for hard spring/age-hardenable applications, platinum/gold and platinum/gold/gallium alloys for casting.