Suggestion re subject.
On the safe edge of your file smooth the very edge of the cutting
teeth on a flat diamond file then polish the safe edge of the file.
We found there can also be a problem with softish stone such as
nephrite jade when it came to polishing the bezel, we usually
overcame that by covering the stone with ‘cello-tape’ and paring it
off right up against the stone.
Keith Torckler, Cornwallis, New Zealand.