There is a lot of information online about card marking and how easy it is. It’s harder to cheat in a casino. Regardless, there are still ways that cheaters can mark cards and remain undetected.
The most common way to do this is to color a small section of the back of the card at strategic places. Other methods include scuffing paint or using luminescent substances. These marks can only be seen by a certain type of light and are usually hidden from view. A cheater can also use special glasses or contact lenses to view the marks. Unlike contact lenses that look like regular ones, these lenses are typically fitted into a pair of sunglasses. This conceals them from the eyes of other players and doesn’t draw as much negative attention from fashion police.
Use of a light-sensitive pen is another option for marking cards. This ink reacts to a specific wavelength of light and is often incorporated into a daub. Cheaters can then bounce invisible light off the surface of the card-back and see the markings through a slightly tinted lens or contact lenses.
Poker cheating glasses are a great way to read the invisible marks on marked cards in gambling. They are also used in magic shows and look like normal sunglasses, so other players don’t suspect that they are cheating devices. Poker players can select from a variety colors.