Image Quality
A poor quality image is often a sign of a counterfeit, which can lose 20 percent of the picture quality, says the Wayne Gretzky Rookie Cards website. A card is likely to be a fake if the image looks heavily pixelated to the naked eye.
Print Dot
The original O-Pee-Chee rookie card has a print dot on Gretzky's shoulder. Check for this yellow mark.
Cut Edges
Original Gretzky cards were cut using a process that generally left at least one side slightly ragged. Perfectly crisp edges on all sides is a sign of a fake.
Indianapolis Racers Card
According to the Puck Junk website, a fake rookie card was released in the early 1990s showing Gretzky as a member of the Indianapolis Racers. Gretzky, however, never appeared in this World Hockey Association set, and no official set was ever released by the Indianapolis Racers.
How to be Sure
The Now Batting 19 Sports Cards website recommends buying cards already authenticated by a reputable grading service -- particularly important if buying cards for the first time.