My first instinct, if the jacket is cleanable, would be to remove the rhinestones prongs and all, and on their place sew just a stitch of colored thread so you know where they go, unless they are all on a trim, then remove the trim. Then clean the jacket and add them back. But of course it depends on how many their are and if the jacket is cleanable. Also, is there a way to spot clean if the area is not near the rhinestones?
If the jacket is very, very old but wearable and striking as is, you may want to leave it alone - I can't say without knowing more about it.