It's Belgian made with the proofmarks you describe. If it has 16 over a C inside a diamond, then it's prior to 1924. Probably does not have chamber length marked either, although it may. On that gun, if it's 16 over a C, then you may also find either 65 or 70MM on the barrel flats, right next to where the flats stop.

Chevalier is likely the name of the gun shop in Paris for which the gun was made.