Watches
Platinum in the watch industry
Platinum is mainly used in the watch industry to produce cases and straps for high quality watches which contain complex mechanical movements. Although a very small amount of platinum is used for watches each year in comparison to gold, nearly all prestige watch manufacturing companies have a platinum watch at the top of their model range.
Production and value
The majority of platinum watches produced in the world are assembled in Switzerland, and Swiss Assay Office statistics reveal how the production of platinum watches has grown during recent years. From 1,200 watches in 1987, output reached almost 13,000 watches in 2004. Platinum's share of the precious metal watch market is small, but it has grown steadily, from 0.4 per cent of Swiss 18 carat gold watch exports in 1987 to 2.6 per cent in 2004.
In 2004 the average value of a platinum watch exported from Switzerland was 22,000 Swiss Francs, compared to an average of 6,000 Swiss Francs for an 18 carat gold watch. The additional value reflects the higher precious metal content of the case and strap, the additional time required to work in platinum and the expense of setting up tools and equipment for the relatively small production batches which are typical of platinum models. Watchmakers also tend to encase their more complex and expensive movements in platinum.
How platinum watches are made
Platinum watches are normally made from 95 per cent pure platinum alloy, usually alloyed with ruthenium. The basic material is homogenized by hammering and annealing, so as to eliminate porosity. Even the minutest contamination might cause craters, fissures, indentations or an "orange-peel" effect on the case surface.
Platinum plate or sheet is rolled down to the required thickness and stamped out to form round or shaped blanks, or discs, for the watch case. These are machined in stages by computer-controlled lathes into the final configuration. Up to fifteen different tools are put into action to turn, mill and drill the case and other parts. It takes three times longer to produce a platinum case than one in gold, as slower tool speeds and lower pressures have to be applied to platinum to minimise friction and tool wear.
Having different metallurgical properties to gold, platinum is usually hand-polished by specialised polishers. The intricate process involves eliminating all the machining marks by applying successively finer grades of abrasive paste to achieve the characteristic lunar lustre of platinum. To complete the watch case, winding buttons and watch strap fasteners, also made from platinum, are fitted.
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