The AppeaRing by Leo Smetsers

An audience member chooses a card from your deck and puts it back. You take off your wedding ring and put it on top of the deck. You ask the audience member for his or her phone, and you take a picture of the deck. The picture on the phone will show the deck and the ring, but now the ring has chosen card engraved on it! You hand the ring to someone in the audience, but they will not be able to find the engraving!