Ghost Box - David Powell

The performer places a glass on the table and borrows a finger ring. The ring is placed in a handkerchief and given to a spectator who holds it over the glass. The perfomer then places a small locked wooden box on the table. The spectator is instructed to let the ring fall into the glass. They hear the ring fall but when they look in the glass it is empty. The spectator unlocks the box and inside is their ring!