The high gold content of this alloy (99.5 percent) facilitates marking as 24 carat gold (or Chuk Kam) in many countries. The alloy has a rich yellow colour,virtually identical to that of pure gold, and can be hardened to a peak hardness of 130 to 140 points on the Vickers hardness scale using a combination of cold work and a low temperature (250 to 300°C) ageing heat treatment.