A nice little mental item with the unusual theme of dowsing. There are no gaffs employed. There is no sleight of hand. All you need are the cups and the coins, which may be borrowed.
METAL DETECTOR by Brian Caswell (creator of Trilogy and Cataclysm)
In this effect you successfully dowse and identify hidden metal objects. Borrow or supply six coins, -three similar silver coins and three similar copper coins. Borrow or supply three cups or containers large enough to cover a pair of the coins. The containers don’t have to be identical. You arrange the coins in twos – two silver, two copper and a silver and copper together. Each pair