that maybe this is a good investment also.

The B stands for "Bains de" and the K, well, happy hunting.
The small D is a serial number, probably had version A (nothing), B, C, D, ... in my humble opinion.
Loving to hear your opinion.

https://www.delcampe.net/en_US/collectibles/coins-banknotes/tokens-medals/casino/aa-casino-plaque-chip-fiche-jeton-nacre-mother-of-pearl-100-frf-casino-de-dieppe-france-steevbe-1576989550.html