your season 6 box set

i just bought all the seasons on craigslist and i am having troubles. season 6 discs are a purple tint like a burned dvd but all the rest are a chrome color like any store bought dvd and the case is just a regular dvd case that hold 4 discs. all the others look real and came in the cardboard box sets like they are supposed to. i think i might have been ripped off. can someone please tell me if your season 6 is different from the others and the discs are purple before i go back to who i bought these from and kill them lol.