Research: Collectors may research the history and characteristics of the coin they are interested in, looking for information on mint marks, date ranges, and other identifying details.
Grading: Professional grading services can evaluate the condition of a coin and provide a certification of authenticity, which can help collectors determine the value and rarity of a coin.
Physical inspection: Collectors may use a magnifying glass or other tools to inspect the coin's surface for details and markings that can indicate authenticity, such as mint marks, wear patterns, and other identifying features.
Chemical testing: In some cases, collectors may use chemical testing to determine the metal content of a coin, which can help to identify counterfeit or altered coins.
Expert opinion: Collectors may consult with other collectors, dealers, or experts in the field to help identify and authenticate rare coins, or to gain insight into the history and value of a particular coin.