The properties of a hard 24 carat gold alloy recently developed by Mintek are discussed. The alloy has a rich yellow colour, virtually identical to that of pure gold, and it can be hardened to a peak hardness of 130 to 140 points on the Vickers scale. This hardness is comparable to that of cold-worked 22 carat yellow gold, and almost double the maximum hardness that can be obtained in pure gold. The high gold content makes it possible to hallmark the alloy as 24 carat gold (or Chuk Karri) in various countries, including China, Taiwan, Hong Kong, South Korea, South Africa and Europe. The resistance of the alloy to oxidation at elevated temperatures, and its corrosion resistance in various media, are also discussed.

Author: Madeleine du Toit