Don Wrote: "I've seen Calif high-denomination chips with the clear plug as well. Not sure what purpose it serves, though."

I once bought into a craps game at Ameristar here in Kansas City with a black $100 chip. The pit boss looked it over REALLY REALLY good. I asked what the deal was and he said they someone had painted some other chips black and were able to pass them off as $100's. So they were inspecting all blacks real close.

I guess if they had something like this clear tube running down the middle of the chip, that would be a lot tougher to reproduce than painting a chip black!