Security services of many modern casinos have already forgotten about this once popular form of cheating as marked cards. And it is in vain because this practice has not been forgotten, and its use is not limited to street gambling. The police arrested a man who marked cards at a table for Hold'em poker not so long ago in Connecticut. They found a large amount of cash in his hotel room, clearly intended for gambling, and special equipment for marking cards.

A similar incident happened in New Jersey sometime later, where the cheater marked cards in an old-fashioned way. He did it with a piece of sandpaper glued to the finger. Similar cases were detected in many casinos closely monitoring tables for card games. It is possible that this technique has not disappeared, and cheaters have learned to mark cards more skillfully, so they remain undetected.

A deck of marked cards

How Cheaters Mark Playing Cards

In both the above cases, cheaters were not professional gamblers. Otherwise, they would not have tried to use such banal tricks in a large casino with robust security and acted more subtly. Mandatory inspection discovered their marks, although no one suspected these players of foul play.

We will not put tremendous stress on classical methods used by cardsharps for tens or even hundreds of years. They include the following techniques:

  • making marks with a nail ring or sharp objects,
  • bending over card corners,
  • tucking the entire card,
  • marking cards with vaseline or sandpaper, etc.

All these tricks are for beginners who decide to take this dangerous path. Any experienced manager or diligent security officer can easily detect these frauds.

Yet, not all cardsharks act so primitively. Some use specific solutions that may resemble eye shadow, lipstick, or dust. The problem is that these substances are almost invisible and cannot be seen with the unaided eye. They do not change the card pattern. Eventually, the mark is erased, making it challenging to detect it even at a close examination.

Cheaters can see marks using special glasses or contact lenses. As a rule, if the red color prevails in the design, the marks are made with a solution that can be seen as green through the contact lenses.

The lens has a special coating that creates the so-called red-eye effect. However, progress does not stand still, and now some lenses do not have this drawback. So determining the cardsharp by the color of the eyes is almost impossible. Even sunglasses do not cause strong suspicion. Especially when it is a game of Texas Hold'em and other varieties of sports poker, where opponents play against each other and often hide their eyes from competitors.

How to Detect Marked Cards

Professional cardsharps are sophisticated, and catching them on the hot spot is extremely difficult. The solutions used are only visible through special lenses and do not appear in ultraviolet light. Lenses look natural, and millions now use this vision correction method.

A casino has nothing against cheaters, but it's not so. A casino can minimize the risk of such cheating if it listens to the advice of professionals and at least tries to implement them. And they recommend the following.

  • First, carefully examine all the players in the casino lobby, especially those who look suspicious.
  • Of course, you need to check their cards for any visible damage.
  • If they are okay, but suspicions remain, try to discreetly find out whether the customer wears contact lenses and where he can keep the solution for marking cards.

Remember that the solution can be of a small amount. It's enough to put a thick layer on an object and slowly move your finger. There are cases when cheaters put the solution on the rims of glasses, buttons, cigarette packs, beer bottles, and so on. One known cheater was caught when he always took casino chips in a thick material layer. Women often store solutions in powder, lipstick, and other cosmetics.

Tracing when a cheater puts his fingers into a solution is extremely difficult. If he is experienced and intelligent enough, it will look like a natural movement, unlikely to cause the slightest suspicion. For example, if a substance is on a mobile phone keypad or lighter, he will quietly take it, making calls or getting a light. But pay attention to the movement of his fingers. That's where he can give himself away.

Sealed deck of cards

And once again, check the eyes of the players and their looks. We have already decided that glasses or contact lenses for a client are not a reason to suspect them. However, his looks can tell a lot. Do not think that cheaters will stare at the cards during a hand looks at the mark. Professionals try to do it quickly and still do not observe the distribution process.

If they are ready to talk with you, try to ask them questions or start a conversation about the game. At the same time, look them straight in the eye, forcing them to do the same. Most gamblers try to cast at least a fleeting glance at the cards. If you see that the visitor is highly interested in the process, this may be a reason to look at him more closely.

In any case, do not forget that many professionals do not work alone. A person you suspect of cheating may play only a diversionary role, and the main cheater remains in the shadows and quietly does the work.

They can sit at a busy table opposite each other. At the same time, a significant player can be without lenses or glasses. It all shows that the dealing of cards does not interest him. Therefore, he communicates with the other visitors and waiters, raises a drink from the table, and so on. The partner marks cards and gives him signals, but he plays poorly.

So keep an eye on all the players at the table. Danger to the casino may be from entirely unexpected visitors. But do it carefully and tactfully. In the end, you do not want to make an honest customer feel uncomfortable in the walls of your casino.

In some games, you can use distribution features to make life difficult for cheaters. For example, if a dealer in the Caribbean poker opens the first card, and the remaining four are under them, the cheater will hardly see the mark. Keeping the top card in the deck is also helpful before each hand or exchange. We should not allow the dealer to put the cards in a row.

How to Oppose Card Marking

In our opinion, the greatest danger to the casino is marking cards before they are into play. It must involve employees or card providers.

  1. In the first case, a deck of cards is substituted by a bribed manager or pit boss.
  2. In the second casino, a casino buys marked cards.

To avoid it, streamline the process of using new decks.

  • They may be under constant video surveillance.
  • You may also have a security officer.
  • In short, the more control - the less the likelihood of cheating.
  • Purchase cards from reliable suppliers.
  • It is best to order them directly from the manufacturer, if possible.
  • Try to give access to cards to a minimum number of people before they enter the casino hall.

It is better to be extra cautious than to be cheated. 


There are many ways to mark cards. Indeed, not all of them are well known. Therefore, protecting a casino from it by a hundred percent is hardly possible. So be extremely cautious, carefully work with clients and stop it if you have developed paranoia.

Frequently asked Questions

🤑 Are there many cheaters at land-based casinos?

Various fraudsters have always visited gambling clubs all over the world. Even now, when there are cameras and other advanced technology, cheaters "work" in most casinos.

🃏 Is it possible to mark cards at casinos?

Card marking has always been one of the most common cheats in the gambling industry. It is pretty easy to mark cards, but Casinoz strongly recommends you not to practice such frauds. They are illegal.

❓ How do cheaters mark cards?

There are numerous ways of card marking, such as bending, tinting, etc. Cardsharps can use particular substances visible only through contact lenses. 

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