The continuous high and unstable price of gold presents a challenge to the jewelry manufacturing industry. There is an increasing demand for jewelry alloys with low gold content since the use of these alloys overcomes the rising material cost. However, such alloys cannot be called "gold," and their tarnish behavior and the color are often compromised. To reduce the material cost of karat gold jewelry, the only alternative appears to be in the use of the hardenable alloys that allow the manufacturing of thin wall and lightweight products. This presentation reviews the metallurgy of gold alloy and the hardening mechanisms. It also reveals the compositional limitations for hardening, and yet shows the variety of yellow/green/red colors that may be achieved in the hardenable karat gold-silver-copper-zinc system. The benefits of using the hardenable alloys are supported by comparative data on mechanical testing of finished jewelry made with both regular and hardenable alloys.

Author(s): Greg Raykhtsaum, Dr. D.P. Agarwal