Normally crystals in water resistant watches are pressure fitted using a gasket that is a flat circle around the edge of the crystal, and which fits between the crystal and the wall of the case.
I once watched the technical director of Breitling USA struggle with sealing an Ocean Pro. The watch kept failing the pressure test after assembly. The problem was with fitting that darn case/crystal gasket. The required tightness to keep the crystal in place under a negative pressure differential makes it really hard to insert successfully. It took four, maybe five, tries before it was successful.
Posted on Dec 31, 2001, 6:05 AM from IP address 18.104.22.168