Platinum as a jewellery metal
In most of the countries in which platinum jewellery is manufactured, it is made in a purity of at least 85 per cent platinum. Other platinum group metals - palladium, ruthenium and iridium - and copper and cobalt are commonly alloyed with platinum to optimise its working characteristics and wear properties.
Among the main advantages of platinum for jewellery fabrication is its strength and resistance to tarnish. It can be repeatedly heated and cooled without hardening and oxidation effects, while even the most slender sections of platinum permanently retain their shape, providing a secure setting for diamonds and giving jewellery designers a freedom of invention not always possible with other materials. Perhaps the best example of platinum's technical virtuosity is the tension ring, in which a gemstone is held in place by the tensile strength of the platinum ring shank alone.
