The proof sovereign is a coin produced specifically for collectors and not for circulation. The minting process differs from that of standard coins as they are struck more than once and in some cases 4 times to achieve a very high definition finish. The most familiar proof type are those which exhibit frosted detail with mirrored fields, these are prepared with highly polished dies and chemicals on the die face to produce the frosting effect. Proof Sovereigns produced for Edward VII and George V are known as matt proofs, here the process differs with the dies undergoing roughening by sand blasting to produce the matt finish, there is no frosting effect.