1998 U.S. Mint Premier Silver Proof Set The 1998 United States Mint Premier Silver Proof Set™ includes 5 coins, each bearing the “S” mint mark of the United States Mint at San Francisco. This set comes housed in a handsome display case. This set includes: * (1) Kennedy half-dollar struck in 90% silver * (1) Washington quarter struck in 90% silver * (1) Roosevelt dime struck in 90% silver * (1) Jefferson nickel * (1) Lincoln cent