Sorry that this happened to you, but I really think it is entirely likely that you go the bad bill at the bank, as there have been at least two other reported cases, just recently. You didn't notice it to begin with, because you don't really pay a lot of attention when you get a stack of bills at the bank. Ballerina is a very reputable jeweler and it makes no sense for them to try to do what you are saying they did, which is switch out the bill themselves. In the end it would cost them much more than that in bad PR.