Coin condition and value
In the early days of coin collecting—before the development of a large international coin market—extremely precise grades were not needed. Coins were described using only three adjectives: "good," "fine" or "uncirculated". By the mid 20th century, with the growing market for rare coins, the Sheldon system was adopted by the American Numismatic Association and most coin professionals in the North America. It uses a 1–70 numbering scale, where 70 represents a perfect specimen and 1 represents a barely identifiable coin. The Sheldon Scale uses descriptions and numeric grades for coins (from highest to lowest) is as follows:
When evaluating a coin, the following—often subjective—factors may be considered: 1) "eye appeal" or the aesthetic interest of the coin; 2) dents on the rim; 3) unsightly scratches or other blemishes on the surface of the coin; 4) luster; 5) toning; 6) level of detail retained, where a coin with full details obviously is valued higher than one with worn details. If the coin is judged favorably in all of these criteria, it will generally be awarded a higher grade.
Damage of any sort (e.g., holes, edge dents, repairs, cleaning, re-engraving or gouges) can substantially reduce the value of a coin. Specimens are occasionally cleaned or polished in an attempt to pass them off as higher grades or as uncirculated strikes. Because of the substantially lower prices for cleaned or damaged coins, some enthusiasts specialize in their collection.