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
Gold coin precisely by a gold plated tungsten core, since tungsten has only 99.74% of the specific gravity of gold. However, forgeries of alloyed gold coins (such as American gold eagle or Krugerrand made from a crown gold alloy with 22 karats = .917 fineness) may have correct the correct weight and dimensions because of the lesser density of the alloy. Such forgeries can be detected testing the acoustic, electric resistance or magnetic properties. The latter method uses the fact that gold is weakly diamagnetic and tungsten is weakly paramagnetic. The effect is weak so that testing requires strong neodymium magnets and