This is not a new subject by any means, but it at least a few times a month I see people incorrectly using the terms “Proof”, “Mint”, “Uncirculated” so today I will try to explain these terms.
Uncirculated simply refers to a coin that has never been used in commerce and does not exhibit any signs of wear. In other words, an uncirculated (or “unc”) coin is a new coin that is in the same condition that it was when it was first minted.
Contrastingly, the terms Proof and Mint, do not refer to condition of the coin. In a way, these terms refer to the process used to produce the coin. A proof coin is created using specially polished dies and specially polished planchets (blanks). As explained by John Lynn on his web site:
By treating the die in a special way, the coins it produces have a different appearance. Modern technology allows the high points on the coin design to be acid treated (on the die). The background (field) design of the coin die is polished, resulting in a mirror-like look on the coin it strikes. This gives the finished coin a frosted look (frosting) on the raise parts of the design, with a mirror like finish on the background. This contrasting finish is often called “cameo”.
Mint coins, on the other hand, use regular unpolished dies and normal planchets. Proofs are usually made for testing and demonstration purposes, as well as for sale to collectors, while mint coins are generally produced for circulation.
Following are image of a Jordanian 100 Fils 1955 (mint and proof), as well as a Jordanian gold commemorative 50 Dinars 1977 (mint and proof). Jordanian proof coins of 1955 are extremely rare and have an estimated mintage of 10 pieces, while 500,000 pieces were struck of the mint coins for use in circulation. The 50 Dinars was issued along with two other silver coins of 2½ and 3 Dinars (both exist in proof and mint, see them here) to commemorate the World Wildlife Fund. 287 proofs and 829 mint coins were made.