Larry; These security dots have been on several Atlantic City higher denomination chips for quite awhile. The earliest one I picked up on was with the TropWorld $25 chip. On the reverse of the elephant chip side is a large numeral "$25". The earlier version did not have the security dot, while later (re-orders perhaps?) did have the dot prominently visible on the base of the numeral "2". Of course the entire TropWorld rack has been replaced with Tropicana chips since then.