Open up your deck of bicycle cards and weed out the advertisements and joker cards. Lay them out on your table face down and examine the pattern on the back of the cards. Bicycle cards all tend to have the same pattern, and in all four corners of the card there are wheels you will mark by house and number to help you identify cards.
Determine in advance which wheel will represent which house. For example, the upper left wheel of your deck will stand for clubs, the upper right spades, the lower left wheel hearts and the lower right wheel represents the diamonds.
Use your razor's edge to make a series of markings in the wheel that connect the outer edge to the inner part of the wheel. For the numbers one through eight, etch a single line from the outer edge to the inner part of the wheel.
Make a line all the way through the card from top to bottom for the number nine and right to left for the number 10. For the Jack, make a diagonal line through the wheel from right to left, and do the opposite for the queen.
Create a cross over the wheel for the King and a plus for the eight.
Repeat this process on each wheel, and memorize your markings, as well as which wheel coincides with which house within the cards. You will now be able to identify cards flawlessly by using this undetectable marking system.