Prediction Chips

Effect: The magician presents a rectangular case. When he opens it, the contents become visible: Five different-coloured good-looking brass chips. The audience can choose a colour, the magician asserts that he knew the colour beforehand, that there is a prediction on the underside of the case. The member of the audience states his colour, the chip is put on the table for examination, the magician holds the case behind the chip at an angle - and it's true, there is a prediction under the case, but it only makes the audience smile. Instead of a true prediction there is only a mirror beneath the case which reflects the coloured chip. But then it gets really magical. All chips are stacked on top of each other, turned over and then spread out again next to one another. This process reveals that the backs of all chips are a neutral white, only one chip has a large, clearly visible mark, a cross, for example. Of course that is exactly the chip with the colour chosen by the member of the...