Three black cards and three red cards are removed from a deck. They are turned face down and interweaved， mixing the colours. The cards are given a little shake and instantly they split into two groups， the reds and the blacks. 

To prove to the skeptics that the cards really do mix， they are mixed FACE-UP. Despite the fact that the cards are clearly mixed， you can square them up and INSTANTLY respread them to show that the cards have again split into reds and blacks 

As an amazing finish， the BLACK cards are dealt into your spectators hands and you show that you hold the red cards， yet instantly the two piles change places in the cleanest way.