Unless you are a professional numismatist, a photo of a PROOF sovereign and a CIRCULATING sovereign, will almost always look the same because they share the same design. And both coins are made from 22 carat gold. But there is a vast difference in the way in which they are produced. And under close scrutiny, they have characteristics that make them very different.
Coins are struck in two different styles and for two distinctly different purposes.
Coins are struck so that they can be used in every-day transactions. We call it circulating currency - coins that circulate. Circulating coins are mass-produced in the millions in what can only be described as a factory environment and distributed through the banks at their face value.
Coins can also be struck to PROOF quality. A proof coin is a specially made coin distinguished by sharpness of detail and usually with a brilliant mirror-like surface. A PROOF coin is never intended to be used.
Proof coins are struck in highly controlled environments. And while today’s production of proof coins has been made faster with innovative machinery, in the nineteenth and twentieth centuries creating a proof coin was a painstakingly slow process. Coin blanks were hand-selected and were polished to achieve a smooth mirror shine. The dies were also specially brushed to ensure the design was perfectly executed and crisp. Because the process was arduous, proof coins were always struck in limited numbers.
So while a brand new circulating sovereign just off the production-line may sparkle it will never have the highly polished mirror surfaces of a proof coin.
Unique Proof 1853 Sydney Mint Sovereign struck at the Royal Mint London.