I used a small amount of Acetone, applied first on a tissue, and then i swiped the glass. I don't think i damaged anything with such a small quantity locally applied on the scratch.
Did it work or is the 'scratch' still present? If it was a paint transfer it should have come off by now. It's possible you have an internal fracture which means a new crystal.
It didn't work. To me this is not a paint transfer but a crack in the sapphire due to a shock.
When i wrote the message it was just happening so i was upset/pissed off but after a couple of days i take it pretty well...
I'll talk to my watchmaker when i'll pass by and keep the forum aware. (not sure this will be this years though)