I recently bought a vintage Girard Perregaux.
Upon receiving it through the post i found that the crystal was completely loose and just fell off the moment i unpacked it.
It is not just the crystal but a metal ring to which the crystal is attached.
When trying to put it back on it sits perfectly (seamlessly) on the watch but it wont tighten or click into place.
Is there a specific tool i need? I know there is a claw-like tool for fitting crystals back in but the fact that its the crystal that is set into a thin metal band makes me think it may not work.
Here is a photo: