the ring is actually your personal property, as is your wedding band. the only time it's required that you give it back, is if YOU break off the engagement prior to the marriage. It's considered a form of contract until the wedding day, and upon the marriage becoming official, the ring is considered a gift to the bride/wife. The only time that a judge might make an exception with rings is if the rings are a family heirloom from his side of the family. So... I'd be calling the police and filing a theft charge against him asap.