When she starts a Paypal dispute, Paypal designates a chatroom and an operator who will try to resolve and settle the dispute between you two. In the chatroom, post images of your receipt / gift receipt for the item you're selling. Post evidence that what the buyer is claiming is false. Also post in the chatroom that you are willing to refund her the money if she ships back the Tory Burch product with delivery/signature confirmation. If she argues and disagrees or doesn't respond, the Paypal representative will resolve the issue in your favour.