John, Thanks for sharing your experience with your burnisher. While I
currently only have a polished metal burnisher, I intend to make
several with agate (and now hematite). I have used stone burnishers
previously and find them very easy to use. I still would not
recommend them for bringing down a bezel but they are wonderful for
smoothing scratches as you say.
By the way, many of my students worry about scratching the stone
when cleaning up their bezels with files. I remind all that, in this
case, Mohs scale is very important and they should be aware of the
hardness of all the stones they set...as well as the tools they use
on them. When setting harder stones such as jades, jaspers, agates,
etc (hardness of 6 to 7.5) you can safely use a steel file (hardness
of about 5.5) across the top of the stone without scratching it.
Same with burnishers. Of course, you must be more careful with the
softer stones such as turquoise, rhodocrosite etc. Also, it is not
wise to use steel files across faceted stones...even corrundum (ruby
and sapphire). Sometimes, if the facet edge runs with the 'grain' of
the stone it can chip. Likewise, I never use craytex wheels along
the top of a bezel....depending on the kind in use, they can be very
abrasive. Finally, never use silicon carbide sandpaper in the area
as it will scratch everything up through corrundum!!
Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1