The attractive color of blue and especially purple gold alloys has always intrigued jewelry designers and producers. The reality of using these colors for jewelry has been very limited, however, mainly due to the inherent brittleness and poor corrosion resistance of this special class of gold alloys. The paper reports on some improvements in crack resistance that are obtained by particular additions to 14K blue and 18K purple colored gold alloys. Opportunities to incorporate such colors in jewelry design with these modified, colored gold alloys using investment casting (as well as the still existing limitations) are discussed. Special attention is given to biometal casting technologies that can be used to manufacture multi-colored jewelry. A protective, transparent and wear-resistant coating finally needs to be applied to minimize corrosion and improve long-term stability of the colored pieces.

Author: Dr. Jörg Fischer-Bühner, Dr. Andrea Basso, Massimo Poliero