I used to work with jewelry. !!BEWARE!!
This method is for face crystals that are completely FLAT! Any convex crystal will shatter without proper tools!!!
Any method of putting the watch cover back with the watch remotely near water/moisture is a mistake. The watch will rust sooner or later.
So if you don't want to pay a jeweler five dollars to put it back on, this is what I did to my sister's watch cover when I could not snap it back.
I took my cushy 1/4 inch mousepad to a vise. You may not have a vise. If you don't, stop reading now and take the watch to a jeweler --one who replaces batteries.
Inside the vise jaws, I used a 5 inch square piece of wood, then my cushy mousepad, then the watch facing the pad, then the back in the right place for restoring.
!!!!NOTE: Not having the back in the right place will smash the stem and damage can/will result!!!
To push the back on, I picked a 12 point socket out of my socket set that was the same DIAMETER as the watch back and placed it CENTERED behind the back.
Recapping, inside vise:
- small board
- cushy mousepad (to avoid scarring and crystal breakage
- watch crystal facing mousepad
- watch back in correct position
- ratchet socket the same diameter as watch back centered behind cover
Slowly I positioned all these items with minimal pressure. Then when I was sure that I was ready (and prepared to hear the crystal break) I put as little pressure closing the vise that I could. The I heard a snap, and to my relief, it was the back going in!
I DO NOT RECOMMEND THAT YOU DO WHAT I DID. People with broken watch crystals become very IRATE when "all it needed was a battery"!
A screw clamp would
also give adequate pressure. Any unsupported direct pressure over the crystal will shatter it!
Hope this helped.