Rob & Joss: You Be the Judge - "The Diamond Dilemma"

Michelle had a very mean Mother-in-Law. Years ago, before Michelle divorced said Mother-in-Laws son, she and the Mother-in-Law were out shopping. On that day, Mother-in-Law lost her diamond out of her ring! The diamond belonged to the Mother-in-Law's grandmother! Well, the ring was replaced with a bigger, more sparkly diamond. A couple of weeks ago, Michelle was cleaning out her car, and what did she find? The DIAMOND! So, should Michelle return it to her ex Mother-in-Law? Or should she keep it for more "interesting purposes?"