Glass refinishing/buffing

This is not a joke: On my car, rust from rainwater running off the paintless roof has caused some rainbow like coloration on the rear window glass. I'm thinking buffing should clear that up, but since the question has been raised, I'm wondering if anyone has had experiance with this?

For what it's worth, I bought the car this way, and it will be sanded and painted as soon as it gets to my garage.