How to dissolve rhinestone glue?

I am attempting to remove rhinestones (Austrian Crystals) from an old costume to reuse the stones as they are extremely expensive. I have tried acetone (nail polish remover) and goo-gone. I let the costume sit in the sun and heat the glue and it didn't really help. Any other methods to try? Please don't say "Buy More Crystals, as that isn't really in budget.Thanks in advance! (: ~Maddie