I recently purchased a Pokemon Sapphire Version Gameboy game.  When I received the game I tried to authenticate it by looking for the embossed numbers on the face and inner lip of the game cartridge.  I knew to look for these because I had read other ebay guides on how to authenticate a Gameboy game.  Neither of these numbers were on the game catridge.  I tried to contact the seller, but he did not respond to my emails.  The seller was "rainqiao07" and the item location in the ad was "Irvine, CA", however, based on the return address on the envelope the game came from "Schaumburg, IL".  The seller also offered a "Money Back Guarantee" if for any reason you were not satisfied with the purchase, however, since he would not answer my emails I could not return the game.