I know that making anything 100% non counterfeit is basically impossible but I was wondering GameCafter or someone else had and ideas or services for making it so cards that I make as the game creator can be told apart from a fan made or illegal copies? I know most games like Yu-gi-oh or Magic have holographic symbols but I'm not how I would apply those or if anyone else has an idea?
I don't believe TGC has an option for that. I also looked into something similar for like foil names and such. I would think the best option for you is while creating the art files hide a small watermark in an obscure area. One not noticeable to people playing the game, but easy for you to find. That's really the only idea I can think of.