The mechanical properties and processing of a newly
developed ternary Au-Sb-Co alloy with 995 fineness are
discussed. The high gold content of this alloy (99.5 per
cent) 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. 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 995 alloy is highly formable, and is amenable
to casting, granulation, remelting, wire drawing,
forming and rolling.