Mental chip prediction

One of our favorite tricks:

You open a case with five different colored brass poker chips. A spectator is free to choose a color.

Explain that there is a prediction on the back of the case. Stack the chips and turn the case over. The spectators see a mirror. Now hold the chips in front of the mirror. The spectators are not enthusiastic.

But if you turn over the spectator's chosen chip, he's the only one with a cross on it! All other chips are white on the back.

Everything can be examined immediately. Including German instructions. This effect works by itself!