There are several varieties in the circulation strike Jefferson Nickel series. Most of them are re-punched mint marks or over mint marks. The 1955-D over S mint mark is considered scarce in all grades. Therefore, any example is quite a find. There are several 1950-D over S mint mark Jefferson Nickel varieties known but FS-034 or OMM-001 is the most popular of all and the one that commands higher prices. The top serif of the S mint mark can be seen underneath the top of the D mint mark for this variety and it is very prominent and easily visible with the naked eye.