PMC3 Charms look terrible now....:(

[MuranoSilver]

I'd avoid the steel wool as it might have contaminants that could be getting into the metal somehow...
try using the polishing papers or very fine sanding pads to get rid of any marks you can.
heat them to white and then go straight to the tumbler to work harden them from there
Nic xx

[Kwant]

May I ask you if the little stone setting cup is the type that comes on a strip like NVY 013 in the Cookson catalogue?

[littlecherryhill]

I tumbled my charms and they turned out way better and haven't gone back to the blackish colour they were turning!

Kwant - I live in Australia and I got my claw settings from metalclay.com.au