Sub-assembly of external parts for timepiece or watch or a piece of jewellery

A sub-assembly of external parts for a timepiece or for a watch or for a piece of jewellery, comprising, coaxially with a first component and a second component compressing together at least one sealing and friction joint, and interposed therebetween, a bolt securing them together by axially blocking said first component, and a lower surface of which is, in the assembled position, in the vicinity of an upper surface of said second component, wherein said lower surface is arranged to cooperate with said upper surface to enclose a ball arranged to occupy, in a static rest position, a well of depth greater than the diameter of said ball that an orientation housing in said second component or said bolt includes, and framed by channels of depth less than the diameter of said ball and limited by limitation borders, which ball can occupy, during an adjustment where it is subjected to the gravity field and/or a magnetic field, both an orientation housing and a complementary housing of depth less than the diameter of said ball, that said bolt or respectively said second component includes, for the relative drive between said second component and said bolt by said ball when it is simultaneously braced on a said channel and a said complementary housing.