First things first. You meant WEST German Interarms, correct? No firearms could ever have been legally imported from E. Germany. If the sight inserts are nickled the pistol is refinished. Manurhin produced some PPK/s pistols finished in Nivel (satin nickel) but Walther did not. I understand Interarms refinished some imports in nickel but don't know anything more; but I'll bet the Interarms pistols had the sights marked.