Even though the ivory chips were made earlier, it is possible that they were used at a casino opening at a later date. However, it is my opinion that the seller is speculating and is relating an illegal casino with the chip for sales incentive. The single monogram chips "D", "L", "M", etc. were primarily used as Roman numerals and markers, as Arabic numeral lammers are used to designate value on stacks of roulette chips, today.