K.Y. Ho
Chow Sang Sang Jewellery Co Ltd,
Hong Kong
Keywords: hard gold, hardness, additive
Summary:
Market has hard gold with fineness 99.9% by addition of different types of additive. Addition of these additives can distort original lattice crystal structure of pure gold. Deformation of the crystal structure becomes difficult and then increases the hardness. However, the addition of these additives cannot be standardized and the casted material cannot be reused to obtain the hard gold result. Here I report that a combination of <0.07% by weight of additives in pure gold to increase the hardness of >99.9% gold to >60~70HV by casting and polishing process. Such formula can increase the hardness to >70~80HV by casting and cold working process. In addition, 100% of casted material can be reused with the same hardness result. The addition of additives and related processing factors can be standardized to ease of control.