Patent ID: 9650697
Date: 2017-05-16
CPC Classifications: C22C,C22F

Claim:
1. A nickel-free and copper-free gray gold alloy, consisting of, in percentage by weight: more than 75% of Au; from more than 18% to 23.5% of Pd; from at least 1.4% to at most 5.9% from at least one element chosen from a third group consisting of Mn, Hf, Nb, Ta, and Zr; either (i) 0% of all elements from a first group consisting of Si, Ga and Ti, or (ii) at least one element chosen from the first group, wherein a total percentage of the element(s) from the first group is from more than 0% to at most 0.5%; either (i) 0% of all elements from a second group consisting of Ru, Ir and Re, or (ii) at least one element chosen from the second group, wherein a total percentage of the element(s) from the second group is from more than 0% to at most 0.2%; and wherein the alloy is suitable for making watches, clocks and jewelry, and has (i) a color that has, in the CIELAB trichromatic space, a value of −2 to 2 on the red-green axis, a value of at most 10 on the yellow-blue axis, and a value of at least 78 on the white-black axis, and (ii) a Vickers hardness index value after annealing greater than 85.