You might try abrasive rubber points - I use these to tidy up my pate de verre, they work well at slow speed on a Dremel, or you can use them in a pin vice as hand tools. No water needed, so you can see the result you are getting.
This is a UK supplier but I'm sure they are available world-wide:
http://www.master-abrasives.co.uk/su...bber-bond.aspx