Can anyone enlighten me as to the characteristics of a cal R 818C I have a late 60s slim dress watch in 18K gold serial (would you believe a double Devil sign) 999666 with a hall mark below and then the letter A which I believe denotes solid 18K
I'm also interest in the function of the screw on the case back which when open looks like it reveals a pin date adjusters one sees on 70s watches.Of course this has no date and is a manual wind. Appreciate any light you can shed on this model.