In 1999 the Mint struck Delaware Proof Quarters in a clad version and a 90% silver version. The 1999-S Delaware Proof Silver Quarters had a significantly lower mintage than that of the clad's. Therefore, making the silver version scarcer as well as more expensive. In PR67 to about PR69 Deep Cameo the 1999-S Delaware Proof Silver Quarters are common. However, in PR70 Deep Cameo condition they are scarce and command a significant premium over PR69 Deep Cameo prices.