This is a vintage card effect we picked up from an old magician’s estate. It comes with the special red backed Fox Lake deck of cards and original instructions. You supply your own envelope or wallet.
Effect: An unsealed envelope is placed on the table in full view. The mentalist explains that it contains a prediction in the form of a blue-backed card.
From a face-up red-backed deck a spectator now selects a card. They have a free choice. Let us say they select the two of diamonds. The envelope is opened and the prediction card removed. When turned face up it proves to be the blue-backed two of diamonds, a perfect match!