Someone gave me a tortoise shell violin frog that is not in pristine condition having a few bumps. Is there any way to buff out tortoise shell or is there no hope for it? I can post a photo if necessary.
There are people who can restore the TS of a frog so perfectly that it is almost impossible to detect the repair. The favored method seems to be filling the losses (how do you have bumps?) with epoxy. However, getting them to carry out such restoration work for paying customers is a different matter.
I don't know about frogs, but I recently tried to buff a tortoise shell pick guard on an expensive guitar. I stopped before I did a lot of damage. The owner didn't seem too upset but informed me that you don't do that.