Two metals, nickel and palladium, are known to be effective bleaching elements when alloyed with gold. Because of the relatively low cost the use of nickel-containing white golds is predominant even in spite of the fact that palladium-containing white gold alloys show much better mechanical properties as well as superior resistance to tarnish and corrosion. Recent European regulations that take effect in early 2013 significantly tighten the allowable nickel release limits, and as a result make all karat nickel-containing white golds a subject to ban. A practical way to offset the high cost of nickel-free palladium-containing white golds is to utilize the effect of age hardening that allows the manufacturing thin wall and light-weight jewelry without compromising the strength and durability. In the present paper we discuss 14K palladium-white hardenable gold alloys, their color and mechanical properties in terms of Pd/Cu and Ag/Cu ratios. 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.
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