1956, 1957, & 1958 Silver Proof Sets in Capital Holders-051825-43 25 July 2025July 25, 2025adminsilvercapital, holders-051825-43, proof, sets, silver Up for sale are the 1956, 1957, and 1958 U. Silver Proof Sets in Capital Holders. These sets include the. 01 denominations and are made of silver with a fineness of 0.9. The sets were struck in Philadelphia and are in uncirculated condition.