A watch case (10) including a middle (11), a bezel (12) and a connecting ring (13) arranged rotatable relative to the middle (11). The connecting ring (13) and the bezel (12) each include at least one interlocking member cooperating with each other when the bezel (12) is fastened to the middle (11) in order to eliminate any relative mobility between the connecting ring (13) and the bezel (12), the connecting ring (13) and the bezel (12) being configured so that when the bezel (12) is subjected to a force that goes against the resilient restoring force, the interlocking members no longer cooperate with each other so as to allow rotational and translational freedom between the connecting ring (13) and the bezel (12).

A device is provided for assembling a casing ring in a watch case middle including a bearing surface on an inner wall thereof, the casing ring including a housing opening in a lateral face of the casing ring, and in an upper or lower face of the casing ring. The device includes a locking part pivotable about a vertical axis of rotation passing through the upper or lower opening from a first position, in which the locking part is housed in the housing, to a second position, in which the locking part protrudes and abuts against the bearing surface of the inner wall of the case middle so as to hold the casing ring in the case middle. The locking part is snap-fitted in the housing and is pivotable about the vertical axis of rotation. A timepiece and a watch case fitted with the assembly device are also provided.

A bezel (1) for a timepiece, including an annular slot (2) with a bottom (20) and two walls (21, 22), wherein a ring made of a luminescent material (3) is disposed on the bottom, the ring (3) being topped by a second ring (4) made of a mineral material occupying the volume of the slot. The bezel (1) includes in each of the two walls (21, 22) a seal (5, 5) cooperating with the second ring (4).

A timepiece (1) including a middle (110) and an interchangeable bezel (200) fastened to said middle (110) by relative rotation of the bezel (200) relative to the middle (110), about a central axis (B), between an interlocking position and a locked position, by a bayonet fastening device (300), said bayonet fastening device (300) including first fastening elements (300a) formed on the middle (110) and second complementary fastening elements (300b) formed on the bezel (200), wherein the bayonet fastening device (300) includes a mechanical coding system (210, 116) for defining a single position in which said bezel (200) can be interlocked with the middle (110).