Monaco, Louis II (1922-1949), Concave Trial 1 Franc (1945) (Aluminum-Bronze, 4.07 gr, 23 mm) KM - (cf. 120a). Uncirculated.
We believe this may actually be a concave flan, as made. This unique trial was produced by passing the planchet through an 'upsetting machine' both before and after striking. The result was to make the coin very concave.