Fournier playing card is one of the best quality poker cards in the world and it has a great soft hand feel. So when we mark the Fournier 2818 into marked cards, it is also very good quality. After specially marked the cards, it looks as original cards.
The most commonly used color of the card back is red and blue.
 
Fournier 2818 can be processed into back marked cards or edge marked cards, back marked card is for infrared contact lenses, edge marked card is for poker analyzer. Both of them can not be seen by naked eyes.

Source: http://www.cheatincasino.com/product/INVSIBLE-INK/invisible-marked-cards/Red-and-blue-Fournier-2818-marked-cards.html