Platinum alloys o f 950 fineness are most commonly used in the jewellery industry. The popular workable alloys (palladium, iridium, copper, cobalt, and tungsten additions) can range in annealed hardness from 50-180 Vickers. Although some alloys can exhibit higher hardnesses, they tend to be brittle. Higher hardnesses promote wearresistance and durability o f the alloys. A need in the jewellery industry exists for harder, yet workable, hallmarkable platinum alloys.

Mintek has developed a range o f platinum alloys that are hallmarkable (950) and can attain hardnesses in excess o f current commercial alloys (250-400 Vickers hardness). These alloys are workable yet exhibit unique hardness properties. These alloys and their properties will be discussed.

Authors: T. Biggs, L.R. Lombaard, N. Adams