Borrow your spectator's ring.
Immediately you pull a sealed brass container from your pocket.
Hand the container to your spectator and instruct them to unscrew the lid.
Better get a chair, this may take awhile (you see the box is very finely threaded.)
After at least 30 seconds the box is finally opened and what do they find inside?
The borrowed ring! Amazing close up magic that fits in your pocket and resets instantly.