Well that’s what I do for a living. As a professional butt saver I
get to see many stones that have been damaged by a myriad of
misadventure. Of course there are accidents but stupidity, ignorance
and inattention provide the most annoying portion of my income.
Apart from these really bonehead moves the most common woops
Stone crushing from resize stretching, Lapis, Malachite, Turquoise with pickle etching, Corundum with borax etching, doing anything with a knife edge girdled stone, wheel damage from bezel finishing, facet rounding from aggressive prong polishing, (tanzanite)
Most jewellers know that certain stones decompose in acid pickle but
I received several lapis rings that were similarly damaged when the
jewellers child left a banana skin draped across them in a hot car.
I believe other fresh fruit would work as well.