Saw the watchmaker modifying a Seiko 5 “fifty five fathoms” model for his customer. The main changes are dial, hands and bezel insert. These days, bezel inserts are held in place by double sided tape. Check out the picture below.
Here, the original bezel insert is removed, exposing the sticky tape on the bezel.
The new bezel insert is then mounted and held in place by the same sticky tape.