I have have repaired several of these. Yes, the chopard ones get
stuck too. The diamonds are set in straight wall bezels slightly
shorter than the height of the chamber. They are floating between
two watch crystals in an outer bezel. The bottom has an overlapping
flange, the bottom crystal is glued in, the diamonds go on top, the
top crystal fits into a groove like a watch crystal, and is glued
with crystal cement. When the glue ages or pieces get excessively
wet, the diamonds start sticking. You take it apart, clean
everything, and put back together.
They float once more..