Mint luster refers to the shiny, reflective quality of a coin that has never been circulated or used. Coins with mint luster often appear bright and have a smooth surface, showcasing their original finish as produced by the U.S. Mint or other mints. This luster is a key factor in determining a coin's grade and value among collectors. The presence of mint luster indicates that a coin has been well-preserved, free from wear and damage. Collectors often seek coins with strong mint luster, as they are considered more desirable and can command higher prices in the market. Coins with this quality are typically graded as MS-60 or higher on the Sheldon scale.