Abstract: A sterling silver alloy composition of exceptional and reversible hardness and enhanced tarnish resistance, consists essentially of the following parts by weight: at least about 92.5% silver; about 4.4% to about 5.25% copper; about 0% to about 1.0% zinc; about 0.85% tin; about 0.05% to about 0.3% lithium; about 0.05% to about 0.5% silicon; about 0% to about 1.2% germanium; and about 0% to about 0.02% boron.

Abstract: A 14-karat gold alloy composition having a desirable yellow color and with reversible hardness contains about 58.65 weight percent gold, about 11.5-25.0 weight percent silver, about 11.85-23.35 weight percent copper, and about 2-7 weight percent zinc. The color of the composition has a value of between about −3.0 to about 0.5 CieLab a* color units, and has a value of between about +20.0 to about 22.0 CieLab b* color units. The alloy has a hardness ratio between about 0.4-2.0, and color ratio of less than about 1.0.

Abstract: An improved 18-karat green gold alloy composition comprises about 75.0% gold; about 6.0-7.0% silver; about 9.0-11.7% copper; and about 6.5-9.0% zinc. The improved alloys are capable of being age-hardened to a hardness of about 240 VHN by being heated to about 550° F. for about one hour, and thereafter being permitted to cool in air. The hard-nesses of the alloys are reversible between their aged-hardness and annealed-hardness values. The color of said composition is between about −1.5 to about −3.0 CieLab a* color units, and between about 19 to about 26 CieLab b* color units.

Abstract: A hardenable white gold alloy consists essentially of about 55-60 % gold, about 12-20% silver, about 8-15% copper, about 8-18% palladium, about 0.0-1.0% tin, zinc indium or cobalt, and, optionally, about 0.005-0.02% iridium and/or ruthenium, and also about 0.01-0.03 weight percent lithium. The alloy is nickel-free, but has a pleasing white color similar to that of nickel-containing white gold alloys. The alloy has a fine grain structure, a lower hardness in its annealed condition, but is capable of being hardened to an exceptional hardness value. The hardening procedure is reversible.

Abstract: Gold, copper, silver, palladium or aluminum and their alloys, but preferably gold or gold alloy, which may be in the form of a wire, has deposited thereon or contained within the wire, a material such as metals or metal alloys which diffuse into the gold or into the other listed metals. With the passage of time and exposure to temperature the deposited metal or metal alloy continues to diffuse into the gold forming intermetallics with the gold and thereby causing the resistivity of the gold to increase and causing the gold to become progressively more brittle until such time as the gold wire ruptures at a stress point. At a given temperature, the elapsed time until rupture takes place depends upon the metal or metal alloys deposited on or contained within the gold. Lead, indium, gallium, tin, bismuth and aluminum and the alloys of these metals diffuse into and form intermetallics with the gold.

Abstract: Gold, copper, silver, palladium or aluminum and their alloys, but preferably gold or gold alloy, which may be in the form a wire, has deposited thereon or contained within the wire, a material such as metals or metal alloys which diffuse into the gold or into the other listed metals. With the passage of time and exposure to temperature the deposited metal or metal alloy continues to diffuse into the gold forming intermetallics with the gold and thereby causing the resistivity of the gold to increase and causing the gold to become progressively more brittle until such time as the gold wire ruptures at a stress point. At a given temperature the elapsed time until rupture takes place depends upon the metal or metal alloys deposited on or contained within the gold. Lead, indium, gallium, tin, bismuth and aluminum and the alloys of these metals diffuse into and form intermetallics with the gold.