Since Plastic Bicycle poker cards have white edge around the back, the invisible marks can also be marked in the white edge as well as in the middle. Our technicians can mark the 4 white corners with tiny marks, including the numbers and suits. Usually when it's difficult to make clear marks in the middle for special patterns of the back, people may choose to make marked cards with tiny marks in the white corners.

As that shows in the picture, it's Club 4 in the left card and Diamond 3 in the right card.