A zinc-free gold alloy containing by weight between 37% and 38.5% of gold, between 4 and 32% of palladium and/or silver, between 25% and 54% of copper and between 0% and 10% of gallium. A timepiece or piece of jewellery or gemstone jewellery made of this alloy.

Preform and manufacturing process producing heterogeneous components with a first fraction (11) made from a first metallic material and having a cellular structure with stochastic or regular cells, and a second fraction (12) made from a second metallic material different from the first metallic material, in which the second fraction (12) at least partly infiltrates the cells of the first fraction (11). The second fraction is poured into the preform which also acts as a mould. The finished product after machining may have a unified surface of the second fraction or several zones exposing the second fraction, the first fraction, the cellular structure which is open or infiltrated with the second metallic fraction, or open zones, in a predetermined design.

According to an embodiment of the present invention, a method is provided for manufacturing an alloy for the decorative article, comprising the processes of: superimposing a plurality of alloys having different colors; heating the alloys; performing a metal diffusion of the alloys on a surface, wherein the alloys are mixed; forming a gradation of the materials across an interface; and processing a mass of the materials to adjust an alloy having a gradation of a color formed and appearing on the surface based on metal diffusion.

A titanium sintered body has an average crystal grain diameter on the surface of more than 30 m and 500 m or less, and a Vickers hardness on the surface of 300 or more and 800 or less. In the titanium sintered body, it is preferred that crystal structures on the surface have an average aspect ratio of 1 or more and 3 or less. Further, in the titanium sintered body, it is preferred that the oxygen content on the surface is 2000 ppm by mass or more and 5500 ppm by mass or less. Further, in the titanium sintered body, it is preferred that titanium is contained as a main component, and an -phase stabilizing element and a -phase stabilizing element are also present.

A nickel-free and cobalt-free platinum alloy including, expressed by weight, from 95.0% to 96.0% of Pt, from 0.5% to 4.5% of Ir, from 0.01% to 2% of Au, from 0 to 2% of Ge, and from 0 to 1% of at least one of the alloying elements Ru, Rh, Pd, Sn, Ga, Re, the respective percentages of all of the elements of the alloy adding up to 100%.

A Gold alloy for jewelry, comprising: Gold: in the amount comprised between 780 and 840 in weight; Copper: in the amount comprised between 125 and 167 in weight; Silver: in the amount comprised between 15 and 54 in weight; Platinum or Palladium, wherein the content of Palladium or Platinum is such that the assembly of Gold, Copper, Silver and Platinum or Gold, Copper, Silver and Palladium reaches a percentage at least equal to 980, and more preferably the 1000 in weight of the alloy;
and wherein the so composed Gold alloy shows, under the conditions referred to in the ISO DIS 8654:2017 standard, a color compatible with the 5N alloy color standard.

A discoloration resistant Gold alloy for jewelry characterized in that it comprises in weight: Gold, in the amount comprised between 755 and 770, Copper, in the amount comprised between 165 and 183, Silver, in the amount comprised between 28 and 50, Palladium, in the amount comprised between 19 and 23 and Iron, in the amount comprised between 2 and 6.
and characterized by the absence of Vanadium.

A watch part containing a titanium alloy, the titanium alloy, in mass %, includes: Al: 1.0 to 3.5%; Fe: 0.1 to 0.4%; 0: 0.00 to 0.15%; C: 0.00 to 0.10%; Sn: 0.00 to 0.20%; Si: 0.00 to 0.15%; and the balance: Ti and impurities, an average grain diameter of phase crystal grains is 15.0 m or less, an average aspect ratio of the phase crystal grains is 1.0 or more and 3.0 or less, and a coefficient of variation of a number density of -phase crystal grains distributed in the phase is 0.30 or less.

A decorative piece includes a support made of a material having no usable plastic deformation in which at least one hollow is arranged. The hollow is filled with a first material forming a substrate in which at least one housing is arranged. The housing is arranged so that at least one aesthetic element is housable therein. The substrate further includes a gripper elastically deforming to retain the aesthetic element in the housing. The gripper further includes at least one setting element. A method for setting an aesthetic element on a support includes taking a support provided with at least one hollow, taking at least one aesthetic element, filling the hollow with a first material, making a setting hole and a gripper in the first material, and setting the aesthetic element by placing it in the hole and by deforming the gripper so as to retain the aesthetic element.

An improved sterling silver alloy. Like all sterlings, the improved alloy is at least 92.5 percent silver by weight. It has less copper than traditional sterlings: 3.0 percent versus the traditional 7.5 percent. Additionally, the improved alloy includes about 2.75 percent palladium, about 1.0 percent tin, and about 0.75 percent zinc, all by weight. A grain refiner, such as ruthenium, may also be provided. The components of the preferred alloy are melted, degassed, remelted, and then formed into casting grains, wire, and etc. The resulting alloy is significantly harder, as cast, than traditional sterlings: 95-120 Vickers versus 65 Vickers for traditional sterlings. The improved alloy also exhibits improved corrosion resistance. Other than a slightly higher (<200 F.) liquidus temperature, the improved alloy may be worked in substantially the same manner as traditional sterlings. Pieces cast from the improved alloy may be age hardened to about 160 Vickers, if desired.