The addition of 1wt% titanium to gold was found to substantially harden the precious metal and enhance its wear resistance, which makes it attractive for jewellery applications. The enhanced hardening is due to the formation of fine AU4Ti precipitates under the appropriate thermo-mechanical treatments. It has been shown that another hardening mechanism can be induced in wire having a diameter of less than lOO/lm, which is stable to heating in air up to 200°C. These observations are consistent with the formation of a network of titanium oxide inclusions up to lOO/lm below the free surface, which has been reported elsewhere. New results have indicated that thin foil of Au-lTi, which has been subjected to similar thermo-mechanical processing, exhibits similar properties to those of fine wire of this material. Potential uses for the fine wire and foil are described.Age-hardened gold containing 1% Ti (990-gold) represents one of the most significant new jewellery alloys developed in the last 25 years (1). The fact that gold with up to 1% base metal content qualifies as '24 carat gold jewellery' in much of the Far East has provided the opportunity to choose an addition which substantially enhances the mechanical resilience of gold. Following a systematic study of additives which could be used to precipitation-harden gold at the 1wt% level, titanium was identified as the optimum element for this purpose, on both alloy constitution criteria and experimental findings.The addition of titanium to gold satisfies two important criteria for achieving optimum precipitation hardening.