I looked at the scan you posted with the auction. From the scan, I can see rim nick, as others could see as well. Although the chip is in very good condition, its definately not in what we call uncirculated condition. Uncirculated contion means in absolutely perfect edges. It means it has never seen table play at all and thus, will not have any rim nicks whatsoever.

I believe what has occured here is you offered a chip you believed to be in uncirculated condtion, and the buyer doesnt agree. You'll know as soon as you see the chip its the same one or not. After all you have the scan of your chip.

As an honorable seller, I'm sure you will gladly take the chip back. It seems this buyer is not just a run of the mill guy, but rather a well known chipper. I would certainly give him the benefit of the doubt and see the chip first hand. Of course you wouldnt refund his money until you get the chip back. So you have nothing to loose. It's by far the better choice to pursue the return method before you actually accuse him of trying to switch chips. Your first impression may have been that he's trying to pull a fast one, but if you think about it, he most likely is thinking the same thing on you.

So, i think both parties should take a deep breath. Have him return the chip. Take a look at it. If its the same chip, and you agree its not a pristine perfect chip, give his money back.