Proof sets of United States coins are carefully treated after minting to give them a beautiful, mirror-like field. Proof sets possess a different aesthetic quality than Mint sets. The United States mint releases sets of all the coins issued for circulation annually, including cents, nickels, dimes, quarters, half dollars, and in some cases, dollars. After the initiation of the 50 State Quarters program in 1999, mint and proof sets began including the 5 state quarters issued for that year. The state quarter sets are available separately as well. We are proud to offer a wide range of these very popular and collectible sets.