Collectible coins, such as the 1957 Denver dime, also known as the 10-cent piece, are sought after for their historical significance, rarity, and condition. The 1957 dime is part of the Roosevelt dime series, which was first minted in 1946 to honor President Franklin D. Roosevelt. Dimes from the Denver mint are marked with a "D" mintmark and can be found in various grades, affecting their market value. Collectors often seek out rolls of these coins to complete their collections or for investment purposes.