WOOOOOOOOAH!!!11one
A long time ago when I used my White finesse a LOT, it got incredible marked-up smacking into other diabolos and dirt, things like that.
Last night I got some cotton discs, completely soaked them in Acetone (Nail Polish Remover, really) and with only one firm wipe I could clean a perfectly white stripe down the cups.
Maybe 2 or 3 minutes later, I had a completely restored finesse. The same method also worked perfectly for one of my Green Suns, which had picked up an unsightly purple streak from rubbing against some vinyl chairs. Two or three wipes and it was gone.
Acetone is GREAT for cleaning diabolos, Suns and Finesses, anyways.