Hello from Virginia. I am new to this website but not new to coin collecting. Questions: I have a 1968 proof set in cellophane. The rim containing the blue rim is Philadelphia (P) and San Francisco (S). It has one quarter and one Nickle from P mintmark. The other column has a penny with S mintmark. a Nickel with an S mintmark. These coins appear on both ends of the column. The third coin is a dime with no mintmark. I have read that the 1968 dime without the S mintmark should be really shiny but none of the coins are shiny. Is there any additional information out there that I can use.