If I don't trust you, which I don't, there's little reason for me to believe you will bring her back, other than the knowledge that there's no way you're pleased to still have her there.

In any event, your method is needlessly complicated. There's absolutely no need for me to go to your world--since you have to come here anyway, you should just bring her with you, take the necklace when you leave, and be done with it.