Platinum was already known in Central America before the fifteenth century and first mentioned in European literature around 1750. Platinum is an extraordinarily rare precious metal, which makes it of course particularly valuable for watches. The various metals in the platinum group were first isolated in the early nineteenth century. Pure platinum has a grayish white color and melts at approximately 1,772° Celsius; its specific gravity is 21.45 grams per cubic centimeter. Watch manufacturers typically use platinum with a purity of 950 parts per thousand. This extreme purity, along with platinum’s high specific gravity and the difficulty of manufacturing and processing the alloy, ensure that watches housed in cases made of discreetly understated platinum are costly pleasures.