I would require a signed letter from the seller stating the chip is real and not a remake.

I would not let him state "real as far as I know"
It's real or its not. He knows.
Link to Club Royale story.
http://community-2.webtv.net/EURO/TESTPHOTOS/
Scan of a real $1 Club Royale. I had in in my files at $150-$200. IMO It may be worthless today.