If it was a work of art, that you created, it would be different. A scan of a chip, which may not be your design to copy in the first place, is hard to defend.

If the seller is running a scam to sell a chip that they don't own. That would be different. It looks like the person sold the chip which was the same design as your scan.

If the person selling, linked to your site and your scan, then it would really be a problem.

Unless it's something that is unique, rare or something that I had to work to create myself, I don't have a problem with people borrowing scans of chips. Maybe those who don't agree, can explain to me what the big deal is with a scan of a common casino chip?