A tamperproof coin case defined by two interlocking plastic plate members ultrasonically bonded together to define a unitary assembly within which a coin and its certificate of authenticity may be permanently secured. One plate member includes a cavity for fully receiving the other plate member therein, with opposing inner surfaces of the plate members being provided with corresponding cylindrical recesses which collectively form a cylindrical cavity within which a pliable plastic retention ring is disposed for securing the coin in a stationary position and permitting its obverse and reverse sides to be viewed through dome-shaped windows provided on the opposite sides of the case. The case is also provided with outwardly extending circumferential flanges which permit a plurality of cases to be vertically stacked for transport or storage.
