Ron Guth:
The mintage of the Quarter Dollars produced in San Francisco in 1857 dropped to under 100,000 coins, a significant decline from the previous two years. The reason for this decline is unknown, but may have to do with local demand for the denomination. Regardless of the reason, this was the smallest mintage of any Seated Liberty Quarter Dollar since 1849. As a result, all grades are scarce, and high-grade examples can be quite elusive. The PCGS Condition Census consists mostly of Uncirculated examples, but includes an AU58 at the low end. On the high end, the finest 1857-S Quarter Dollar appears to be a lone NGC MS66.
The strike quality of the 1857-S Quarter Dollar is excellent.