The water-resistant watch case includes at least one crystal mounted on an upper side of a middle, a fastening gasket being disposed between an upper annular inner wall of the middle and an upper annular outer wall of the crystal. The crystal includes an annular peripheral surface below the upper annular outer wall inclined at a defined angle smaller than 90° in relation to an axis perpendicular to a plane of the watch case to come into direct contact against an annular inner surface of the middle inclined at an angle similar to the inclination of the annular peripheral surface and below the upper annular inner wall of the middle. The annular peripheral surface and/or the annular inner surface of the middle comprise a domed contact portion for a contact on an annular contact line between the two surfaces.

The water-resistant watch case includes at least one crystal mounted on an upper side of a middle, a fastening gasket being disposed between an upper annular inner wall of the middle and an upper annular outer wall of the crystal. The crystal includes an annular peripheral surface below the upper annular outer wall inclined at a defined angle smaller than 90° in relation to an axis perpendicular to a plane of the watch case to come into direct contact against an annular inner surface of the middle inclined at an angle similar to the inclination of the annular peripheral surface and below the upper annular inner wall of the middle. The annular peripheral surface and/or the annular inner surface of the middle comprise a domed contact portion for a contact on an annular contact line between the two surfaces.

A water-resistant closing device for a watch case, the device including an annular gasket (1) arranged to be placed between a middle (2) and a back (3), a bezel or a crystal (4), or a bezel and a crystal, or a back and a crystal. The gasket (1) has on its middle portion a bulge (10) protruding on its outer lateral face (11), the bulge being arranged to be engaged against the middle (3) and compressed following the installation of the back or of the crystal on the middle, the bulge being delimited by an upper (12) and lower material countersink (13) on either side of the bulge (10) in the non-compressed state of the gasket (1) to facilitate its installation and its deformation.

A water-resistant closing device for a watch case, the device including an annular gasket (1) arranged to be placed between a middle (2) and a back (3), a bezel or a crystal (4), or a bezel and a crystal, or a back and a crystal. The gasket (1) has on its middle portion a bulge (10) protruding on its outer lateral face (11), the bulge being arranged to be engaged against the middle (3) and compressed following the installation of the back or of the crystal on the middle, the bulge being delimited by an upper (12) and lower material countersink (13) on either side of the bulge (10) in the non-compressed state of the gasket (1) to facilitate its installation and its deformation.

A watch case (10) including a back (30) driven into a middle (20) by a joint (40), and including a body (31) from which radially extends a lip (32), the body (31) including an axial annular shoulder (310) and the lip (32) including a radial annular shoulder (320). The middle (20) has an axial opening (21), an axial annular shoulder (200), and a radial annular shoulder (201) resting against the radial annular shoulder of the lip, the joint being interposed between the axial annular shoulders. The axial annular shoulders have peripheral profiles of complementary shapes, substantially circular, including one and the other, a first circular-arc-shaped portion having a first radius (R1, R2), and a second circular-arc-shaped portion to which is connected the first portion, having a second radius (r1, r2) the value of which is lower than that of the first radius (R1, R2).

A watch component comprising an austenitic ferritic stainless steel. The austenitic ferritic stainless steel includes 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, wherein the mixed layer is composed of the ferrite phase and the austenitic phase. 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 device is for fastening a back on a middle of a watch. The back has a shoulder forming a cover arranged to cover entirely partly with the middle and a body arranged to rest in the middle. The device includes at least one pin integral with the middle, a seal mounted between the back and the middle. The back includes, near its periphery, at least one groove, the pin being arranged to slide in the groove between a first position, called the insertion position in which the back is free, and a second position called locking position in which the back is locked and positioned angularly relative to the middle. The groove includes at least one bump to form a hard point and increase the torque when the pin passes through the bump.

A device is for fastening a back on a middle of a watch. The back includes a cover arranged to form a bearing surface with the middle and a body arranged to rest in the middle. The device includes a ring disposed between the back and the middle, the ring being arranged to ensure the water resistance and indexing of the back. The ring includes an upper part ensuring the water resistance and a median part including positioning to ensure precise placement of the back.

A device is for fastening a back on a middle of a watch. The back includes a cover arranged to form a bearing surface with the middle and a body arranged to rest in the middle. The device includes a ring disposed between the back and the middle, the ring being arranged to ensure the water resistance and indexing of the back. The ring includes an upper part ensuring the water resistance and a median part including positioning to ensure precise placement of the back.

A mechanical or electromechanical timepiece including a watch case delimiting an internal volume, the watch case including a back delimiting the watch case at the bottom; a crystal closing the watch case at the top, the crystal defining a useful display aperture; a middle part connecting the back and the crystal to one another; a horological movement housed in the internal volume of the watch case; at least one hand for displaying information visible via a useful display aperture and rotated with respect to the watch case by the horological movement with at least one driving belt extending at least partially in the useful display aperture, the timepiece includes the internal volume of the watch case filled with a fluid wherein at least one driving belt is submerged, and wherein the driving belt is made of a material wherein the optical refractive index is equal or substantially equal to that of the fluid.