How to mark a playing card

If you are a playing cards fan, I think you may have heard that in some poker games, some people use marked cards to cheat in the game.so, today I'm going to introduce something about mark playing cards.Fortunately, it is easy to mark playing cards if you aren't  too obvious. what we need is a little bit of time and sly skill.

   Things we will need to mark cards:

• A coder or a marker
• A deck of playing cards 
• Organize your playing cards. Separate and organize your cards by value. For example: make a stack of all ones. In this way, it will help you to identify and quickly locate them so you can mark playing cards. You will also find out if you have any missing cards via this way.  
• Choose which cards you would like to mark. If your playing cards are organized correctly, then you could easily grab the cards from their stacks. Put all the chosen cards into their own stack together.
• Take the coder or marker and begin marking your chosen playing cards. First, we should note not to make your markings too large and obvious.The mark should be small and less noticeable. we can try a different figure, color, or whatever we use to make the code easy and known to us.We can mark in the middle of the card with a big font, or mark the figure in the four corners of the card.

Here I'd like to show you a card with mark which can not see through naked eyes,but with special lenses.