Cleaning Cabochons

[Donna@Rockin' Beads]

OK, I have managed to make 4 cabochons (hopefully to be turned into 2 pairs of cufflinks, although the first 2 are decidedly dull and misshapen and the second pair are quite different in size from eachother ('well, they are handmade' I hear you all cry  ).
Anyway, so I've scrubbed the backs with a nail brush and just can't seem to get the last residue of bead release off them.
What do you guys do to clean them up?
Do I just have to keep soaking and scrubbing? (I seriously hate elbow grease!!!)

[Redhotsal]

Wet'n'dry 

[Donna@Rockin' Beads]

Ah, of course.
Thanks Sal