I’m new here so I didn’t read the beginning of this thread, I hope my
ramblings don’t rehash previous comments. I think the answer to your
question is it depends on how “minor” the scratches are.
A customer once successfully polished a scratched opal in its setting
with (I think it was) tin oxide, entirely by hand on a moist towel
while watching TV each evening (Jeopardy and Wheel of fortune, she
said). It took her a week and she LOVED to talk about it.
I have succeeded in polishing scuffed/scratched showcase windows –
the sort of thing that happens when some ungainly metal display item
rests against the glass while driving cross-country in a panic to get
to the next show on time. In that case I used a dremel with felt
cones, it left slight wavy surfaces of course.
Polishing stone (or glass) is really a process of finer and finer
scratching with smaller and smaller abrasive particles. Usually even
minor looking scratches are deep enough that their removal means you
have to start by lowering the surrounding surface with a more
aggressive abrasive than cerium oxide alone – thats usually the final
polish after finishing intermediate steps.
Some stones - notably malachite and turquoise - are soft enough than
you can simply buff them on a regular cloth wheel with yellow rouge.
They do tend to become lumpy if you take this too far, but it will
work fine in a pinch if you’re careful. Alan Heugh