Among the main advantages of platinum for jewellery fabrication are its strength and resistance to tarnish. In most of the countries in which platinum jewellery is manufactured, it is made in a purity of at least 85 per cent platinum. [[File:T--Aix-Marseille--Jewellery.png|300px|right]] 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.