CHEATING PLAYING CARDS
Cheating playing cards are printed or altered so that the cheater can know the value of specific cards while only looking at the back. Ways of marking are too numerous to mention, but there are certain broad types, like cards marking (mark it on a circular design on the card so that it can be read like a clock, marking an ace at one o'clock, and so on, until the king is not marked), and print with invisible ink (the marks made on the back will disappear when the ink getting dried).
CARDS MARKING DECK
Cheating playing cards are originated from cards marking. The card marking is a process of changing the playing card in a manner that is obvious to the marker or conspirator, for example by bending or adding a visible mark to a card, either by punching holes through the middle of cards or trimming their edges, or cutting-out, using a razor to scrape off some of the printed areas of the card, such as adding (cutting out) a white bird to the back design.
This allows different methods of card sharpness to poker cheat or can be used for magic. To be effective, one or more distinct markers must be seen on the front side of the card, and these markers are generally uniform. By looking back, this kind of initial cards marking deck is rough and foolish; we can see the mark apparently. It's hard to ignore. And its biggest shortage is that it can't mark the whole deck of cards.
Several decades later, cards marking deck has technical improvement. People started to use printer to alter the patterns and color of the cards design. It's a subtle mark on the decorative side of the cards; placed in a certain position to indicate the number of the card, with the color or shape of the mark indicating suit. For example, a round designs on the card so as to be read like a clock (an ace is marked at one o'clock, and so on until the king, which is not marked). At this period, the cards markings have rules to follow, and the cheater can know the value of specific cards while only looking at the back. It's in high quality level. All the cards markings blur out on distance and will get invisible across the poker table.
Bicycle Ultimate Marked Deck 
Phoenix Marked Cards 
Fournier 818 Marked Deck INVISIBLE INK MARKED CARDS
What is Invisible Ink?
Invisible ink, also known as security ink, is a substance used for writing, which is invisible either on application or soon thereafter, and can later be made visible by some means. Invisible ink is one form of steganography. Says Wiki. Invisible ink playing cards are kind of senior marked cards that using marked cards printer to print unified marking on the back, including cards suits and value.
Around 600 AD, and in the 16th century in Europe, lemons were used by Arabs as organic inks. This is the first time that lemon juice used as invisible ink to hide some secret information. But this lemon juice can't mark on the playing cards, the effect is not stable. Then until last 90s century, the technical of marking cards with invisible ink is getting mature.
Cards Marking of Invisible Ink
At the beginning, people invented invisible ink pen to mark cards. They make any marks only they know on the back of the playing cards, to indicate the cards value. At this time, the effect of this invisible ink is better than the lemon juice, but is still not stable enough. The hidden marks is too strong that easy to reveal, or too light to see clearly.
Then, with the development of science and technology, people invented the marked cards printer. The invisible marks made by marked cards printer are card values that fused to the pattern of the card's back, incorporated into the back image so that they do not attract attention when fleeting, and it will not dull the finish of the cards and that it works on both paper and 100% plastic playing cards.
No long later, people improved the invisible ink and the Printing Technology. They can make a barcode marks, like the QR code, on the four edges of the playing cards. It's called barcode marked cards. You can't see the cards' values and suits of each card directly. It needs to use with poker analyzer and scanner camera. Once the dealer shuffles and deal the barcode card to the players, the infrared scanner camera will read the invisible “barcode” printed on the card, the analyzer processes the data, and sends a voice message to the spy microphone. All analyzers are needed to set the number of players, it can be done by remote control as well.
When you order a pack of marked cards, it is shipped with its seal and plastic wrap “intact,” This makes the other players less suspicious, as the pack can be opened in front of their eyes.
Bicycle Prestige Invisible Ink Marked Playing Cards 
Copag Jumbo Face Invisible Ink Cheating Cards 
Barcode Marked Cards for Poker Analyzer Devices 
Contact Lenses for Poker Cheat Cards 
KEM Luminous Ink Marked Cards 
Marking Cards with Invisible Ink Pen Devices to Detect Cheating Playing Cards
Naked eyes. At the cards marking period, you can detect the flaws easily just by looking through the surface of the cards deck, but all the cards markings blur out on distance.
Ultraviolet light pen. For invisible ink pen marked cards, ultraviolet light is enough to check the hidden marks. Many supermarkets have ultraviolet light pen on sale.
Invisible ink contact lenses for cheating playing cards. If you want to detect the professional invisible ink marked deck, you need some professional tool as well.
Infrared poker camera is one of the most advanced playing cards cheating devices. It is used to read the special infrared ink marked playing cards in a long distance.
Barcode poker scanner. As we mention above, QR code cards are the latest cheating cards, except for poker scanner camera, no other tools can detect the hidden barcode.
Why We Need Devices to Read Invisible Ink?
There are three kinds of cones (red/blue/green) on the human eye. These three cones determine that people can only see light with a wavelength range of about 400-780 nm, called visible light, from purple to red.
Lightless than 400 nm is located outside of purple, called ultraviolet light, and light larger than 780 nm is located outside of red, called infrared light, which is outside the visible light and is invisible to humans.
The invisible ink is purple and red, the reflect wavelength of them is less than 400 nm and larger than 780nm, that both of them are beyond the visible light wavelength, so we need to use with tool like infrared contact lenses, can we receive the light reflection of these two colors.
Using Cheating Playing Cards in Poker Game
Poker is a game of luck and skill. Luck is a little more fickle. The skill is something you can account for and improve, for example, using cheating playing cards. By using physical objects, evaluate the value of the deck or prepares for a victory with a marked or ordered deck. With a little practice and preparation, the odds will be in your favor.