I always thought it was a security measure that followed a mathematical sequence with a pattern known only by the manufacturer and casino against counterfeiting.

I once posted a series of numbers here to see if there was an obvious pattern that someone could figure out, but no luck.

These are hand engraved, too.

Ten pieces were found at a Paris antique shop 25 years ago. I called on our friend in Liege to close the deal and never seen another piece, anywhere, since.