Cleaning Crystals, literally

[FairyCrystal]

I don't mean cleansing energy, but literally cleaning a crystal.
Not always easy to decide how to do it or what to use.

I have a tumbled jade that I had taped to my neck a while ago. Unfortunately the glue from the tape stuck to the jade and I couldn't get it of. Never had problems with the tape in the past, I suspect they changed the glue?
I put it away and forgot about it, tonight picked it up, and dang! A thick white sticky layer of glue.
Now what? I wanted it of, no matter what, I couldn't use the crystal like this.
Tried with my fingers, nope. Tried a scrubbing sponge with detergent, nothing. Then I decided drastic measures: scrape it off with a knife. I figured better risk some scratches than use chemical glue solvent. So a sharp knife it was. It worked!
The last thin bits and pieces I could rub off on my jeans. Done, clean crystal again! And... as far as I can tell, not a scratch on it.
Not using this tape on my stones anymore.