Guys: Did a bit more research. Warning on this.
Some CA debonders contain acetone. Which disolves plexiglass over time, and of which I believe plastic watch crystals are made.
So a few things to consider:
- If you have acetone on hand, it can de substituted for debonder, but it will likely melt / mar your crystal
- Research the debonder you use, and test it on an old crystal first if you're trying to salvage it
I've marred plexiglass with chemicals before. If it happens, a soap/water wash will stop the chemical action. Then sand/buff as usual. Maybe you'll get lucky.