About Proof Sets

Preparation of a proof striking usually involves polishing of the dies. They can usually be distinguished from normal circulation coins by their sharper look and design, as well as much smoother “fields” - the blank areas not part of the coin’s design.

The dies for making modern proof coins are often treated with chemicals to make certain parts of the design take on a patina.   The polished fields take on a mirror finish. Several other methods have been used in the past to achieve this effect, including sand blasting the dies, and matte proofs. Proof coins of the early 1800s even appear to be scratched, but it was part of the production process.

Most proof coins are double struck. This does not normally result in doubling that is readily observable, but does result in the devices being struck fully.