An electrochemical cell arrangement using a bipolar plate is disclosed, wherein the bipolar plates are formed from single or multiple sheets of metal foil, preferably titanium, embossed with the fluid fields. Authentication data is encoded in the gemstone from the relative spatial arrangement of the dot-shaped marks that form the indicium. Delay detection circuitry compares the actual loop delay to a reference loop delay. The cover is fitted into the opening with the projection into engagement with the inner plate on one side edge of the opening and the engaging member is then brought into engagement with the inner plate on the other side edge thereof, thereby fixing the cover to the inner plate to plug the opening thereof.