Canada Stamp # O11, 50 Cent Oilfield, OHMS, MNH, VF, CV $40.00. This green 1950 stamp from the George VI era features the denomination of fifty cents and has a very fine grade. It was issued in Canada and has never been used, with mint never hinged certification. The stamp shows the oilfield theme and is an Official stamp, with OHMS printed on it. The stamp has a catalog value of $40.00.