Luminous Ink For Trick Devices
The word luminous here does not mean you can see something directly rather than from the help of some tools. And by the scanning tools, then you see the luminous symbols marked by producers or individual, and that stuff often made of special juice or invisible inks. Remember some scenes about detectors or treasure hunts from some films? Always the secrets and treasures are only under dark light and ultra luminous readers. Smart people choose print texts in a hidden way, and I guess cheaters are kind of that smart too.
There are two kinds of luminous marked cards: IR luminous marked card and UV luminous marked card. All these marked cards can be read after wearing a pair of special infrared contact lenses and luminous enhancing sunglasses, and naked eyes of human can not see anything different to regular cards. Various kinds of poker cards can be processed into those two types, they are done with the original pack. If you know the how-to stuff about card marking, then you will see often two places on playing cards may emerge the signs, one is right front back and the other is around corners.
And still a notice here, those two IR and UV can not be messed up, both are readable only by each detecting devices, that being said, for example, if a card cheater apply infrared radiation filter to infrared marked cards, he or she only get the results in infrared wave, that means you can not see other parts of things, others will be all black. So if you wanna buy these cheating type of devices, I would like to suggest you take some time to do some real research and educate yourself well(here is a forum post from 2 plus 2 would do some work for you), after that, you may figure out what to do and where to find one.