Restless Colors by Roy Walton and Aldo Colombini
What a fantastic routine this is!
A packet of four blue-backed cards (say all 8 of Clubs) changes to red-backed cards, then to green backs and then to yellow.
Then the four cards are one of each colour and for a stunning finish, the four cards change into the four aces (or blank cards with a message, Jokers, Kings ,Jacks, etc.)!
Complete with special cards and DVD