A customer recently purchased a pair of old agate beads from me, and is determined to clean them and enlarge the drill holes.

I've explained that I am doubtful a bead reamer would be appropriate in this situation, recalling an acquaintance who once had a drill bit break off inside a carved amethyst bead.

As to re-polishing the surface, that seems more like something a vibratory tumbler would be needed for.

I recommended she contact the lapidary/mineral clubs in her area to see if anyone had the equipment and would be willing to take on her bead.
San Francisco area.

No, please don't go on about not cleaning old beads until they looks sparkling new. She knows what she wants, and they're her beads now.