The magician shows a special deck of cards to the audience.
Although it appears to be a perfectly normal deck, it has a hidden compartment in which a valuable ring can be hidden.
If a burglar sees it, it wouldn't even cross his mind that it could contain something valuable. Even if he does take it with him, it's still not a problem since the deck makes the ring disappear!
The magician brings out the disappeared ring from his pocket.
Both the deck of cards and the ring can be immediately examined.
This trick is most effective if you use a ring borrowed from the audience, or a coin marked in some way.
A special deck of cards and a pretty ring, just in case you don't want to borrow one from the audience.