A layer of lanthanum boride of stoichiometry LaB.sub.x where x is between 9 and 12 is deposited on substrate, for example a stainless steel watch dial, and subsequently treated with a laser, such that the portion(s) of the layer treated with the laser change colour according to the laser power. This produces multicoloured surfaces having high resistance to corrosion and abrasion. The layer of LaB.sub.x is deposited by PVD and by cathode sputtering, using a LaB.sub.6 target of purple-violet colour, such that the colour of the deposited layer differs from the colour of the target. The laser treatment at specific powers changes the stoichiometry of the layer in the treatment portions, such that the colour of these portions changes according to the stoichiometry obtained. At higher powers, the laser will remove the layer of LaB.sub.x. Thus the colour of the treated portions is determined by the material of the substrate.

Method for coloured coating on a watchmaking or jewellery external part component, comprising at least one visible surface prepared in advance on a substrate, this method comprising a step of vacuum-deposition of at least one main layer of titanium and silicon nitride (Ti, Si.sub.k)N.sub.x or of titanium and silicon nitride doped with oxygen (Ti, Si.sub.k)N.sub.xO.sub.y.

Disclosed is a coating composition for watch elements, comprising a binder, preferably a two-component polyurethane; one or more pigments, preferably in quantities from 19 to 58% by weight of pigments (based on total solids of the composition); at least one filler; a solvent or a solvent combination, preferably butyl acetate and/or ethyl lactate. optionally one or more commonly used additives, customary auxiliaries or combinations of them.

Further disclosed are a kit-of-parts, a coating on a watch element, a process for coating a watch element and a watch obtainable by said process or comprising said coating.

A watch component is comprising an austenitic ferritic stainless steel, the austenitic ferritic stainless steel including a base portion composed of a ferrite phase, a surface layer composed of an austenitic phase, and a mixed layer formed between the base portion and the surface layer, the mixed layer being composed of the ferrite phase and the austenitic phase, in which the base portion contains Cr: 18 to 22 mass %, Mo: 1.3 to 2.8 mass %, Nb: 0.05 to 0.50 mass %, Cu: 0.1 to 0.8 mass %, Ni: less than 0.5 mass %, Mn: less than 0.8 mass %, Si: less than 0.5 mass %, P: less than 0.10 mass %, S: less than 0.05 mass %, N: less than 0.05 mass %, C: less than 0.05 mass %, and a balance being composed of Fe and inevitable impurities, in which the surface layer contains 1.0 to 1.6 mass % of nitrogen, in which the surface layer has, at a surface of the surface layer, an oxide film having a thickness of 2.5 nm or greater, as calculated in terms of oxygen profiles in AES analysis.

A watch component includes an austenized ferritic stainless steel including a base including a ferrite phase, a surface layer formed on a surface of the base, the surface layer including an austenized phase, and a mixed layer formed between the base and the surface layer, the mixed layer being a layer in which the ferrite phase and the austenized phase are mixed. In a cross section taken along a depth direction from the surface, a thickness of the mixed layer is 45% or less of a thickness of the surface layer.

A watch component includes a metal material obtained by performing a nitrogen absorption treatment on a base material, the base material being a ferritic stainless steel that contains, by mass %, 18 to 22% of Cr, 1.3 to 2.8% of Mo, 0.05 to 0.50% of Nb, less than 0.5% of Ni, less than 0.8% of Mn, less than 0.5% of Si, less than 0.10% of P, less than 0.05% of S, less than 0.05% of N, and less than 0.05% of C, with a remainder thereof being composed of Fe and an unavoidable impurity.

A black member includes a base and a black layer laminated on the base. The black layer contains titanium aluminum nitride, titanium silicon nitride, or titanium aluminum silicon nitride. The black layer may also contain at least one type of elements selected from the group consisting of oxygen, fluorine, and carbon. When the black layer contains carbon, and assuming that a total amount of elements contained in the black layer is 100 at %, the black layer contains carbon of 10 at % or less. In a color evaluation according to an L*, a*, b* color system (CIE color system), the black layer satisfies L*48.0, 2.0a*3.0, and 3.5b*3.0.

A method for fabricating a timepiece component made of conductive material includes: making a base from conductive material; coating the base with a first layer of sacrificial metal protection material; etching a recessed decoration mechanically or with a laser; coating the first recessed decoration and the remaining part of the first layer with a second metal and/or coloured decorative treatment layer; and removing each first sacrificial metal protection layer by chemical devices, to obtain a blank including a first decoration formed by the remaining part of the second layer.

A method for brazing a first ceramic component and a second metal alloy component, to make a structural or external timepiece element, a zirconia-based ceramic is chosen for the first component and a titanium alloy for the second component, a first recess is made inside the first component, set back from a first surface in a junction area with a second surface of the second component, braze material is deposited on this first surface and inside each recess, the second surface is positioned in alignment with the first surface to form an assembly, this assembly is heated in a controlled atmosphere to above the melting temperature of the braze material, in order to form the braze in the junction area.

The invention concerns a timepiece member including a first axis and a first threading intended to cooperate with 5 a second threading provided on a second timepiece member. The first threading is configured so that a zone of contact between the first threading and the second threading extends over less than 50% of the height of the threads of the second threading or is configured so that the zone of contact between the first 10 threading and the second threading extends over less than 0.3 times the pitch of the threading.