They are not chips , they are what we used to call " markers " .
They would be placed on the roulette wheel or at the side of the BJ tray to indicate how much money had been advanced to a client on credit .

This was made illegal some time ago , and I doubt they are made nowadays .

If we ran out of markers ( or " buttons " ) , we would use high value chips or plaques to show how much the client was " in for " .

The most I ever saw stacked up on a roulette wheel was £ 1,250,000 in £25,000 plaques . I could hardly spin the ball !