A Chinese coin is openly placed on the table so that it can be identified by it's center hole and Chinese characters.  A spectator is then asked to estimate the coin's value.  After stating his estimate, the magician touches the coin with a playing card by flicking the card on top of it.  Instantly the Chinese coin is transformed into a quarter!  
 
The playing card and coin may then be given out for examination.
Nicely made and easy to do.