Pinchbeck (alloy) Pinchbeck (alloy) Pinchbeck is a form of brass, an alloy of copper and zinc, mixed in proportions so that it closely resembles gold in appearance. It was invented in the 18th century by Christopher Pinchbeck, a London clockmaker. Since gold was only sold in 18-carat quality at that time, the development of pinchbeck allowed ordinary people to buy gold 'effect' jewellery on a budget. The inventor allegedly made pinchbeck jewellery clearly labelled as such. Pinchbeck jewellery was used in places like stagecoaches where there was a risk of theft. Later dishonest jewellers passed pinchbeck off as gold; over the years
Colored gold be also used for such effect. Gold-cobalt-chromium alloy (75% gold, 15% cobalt, 10% chromium) yields a surface oxide that's olive-tinted because of the chromium(III) oxide content, is about five times thinner than Au-Co and has significantly better wear resistance. The gold-cobalt alloy consists of gold-rich (about 94% Au) and cobalt-rich (about 90% Co) phases; the cobalt-rich phase grains are capable of oxide-layer formation on their surface. More recently, black gold can be formed by creating nanostructures on the surface. A femtosecond laser pulse deforms the surface of the metal, creating an immensely increased surface area which absorbs virtually all the