For years manufacturing jewelers have experienced prong failure when using both die-struck and investment cast 14Kt nickel-white gold Tiffany heads, usually during the final operation of stone-setting. As a consequence of these failures, time-consuming and therefore expensive replacement of the setting must be carried out to complete the finished article. Examination of the failed component often reveals a brittle, inter-granular failure typical of stress corrosion and not other inherent component defects. This suggests the failure mechanism is process related and, as such, avoidable. This paper outlines a study undertaken to determine the metallurgical principles involved in the failure process and identifies the conditions required for failure to occur. Information is documented on processing techniques and parameters necessary to minimize the risk of failure due to stress corrosion when using 14Kt nickel-white golds, and will demonstrate why this phenomenon does not occur when components are manufactured from a 14Kt palladium-white alloy.

Author: Stewart Grice