The term “marked cards” refers to a deck of playing cards that have been altered in some way so that it becomes easier for someone to identify them. Marked cards are often used in card games to cheat. Honest players should be aware how they can be marked to avoid being cheated.
In the past, cards were marked by bending them and crimping to make the subtle markings indistinct to spectators. Later, people began to use more sophisticated techniques to mark cards. These included pinpricks and cutouts. Some of these methods are only detectable through specialized gadgets, and others require a very high level of skill to execute.
Another way to hide any visible markings is to apply a chemical called “juice dust” or “daub”. This can be done while playing. Lastly, video-luminous markings can only detected with special sunglasses and cameras. This technique was developed by magicians who use it to read their opponent’s cards. However, some professional gamblers have also used it to gain an advantage.
The best marking system should be undetectable by spectators, and easy to read for a magician at a glance. Tiny markings can be difficult to distinguish, and they can cause the magician to make mistakes that will hurt their performance. A small mark on the corner of the card can indicate that it’s a mountain, Loxodon Hierarch or Lightning Helix, giving the player an unwarranted knowledge of the card’s powers.