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Definition: Roller marks are parallel lines, gouges, or grooves on the surface of a coin that continue underneath the devices and inscriptions. Roller marks are caused by debris getting onto the sheet of metal, or caught in the rollers, during the preparation of the metal sheets from which the coin blanks are punched out. Roller marks can also be caused by other mint processes that don't involve any rollers at all, but since the damage looks the same, the term roller marks is widely used to desscribe all types of long, straight, parallel lines that were on the planchet before striking.
See also: Photo Diagnostics for Roller Marks and Adjustment Marks.
Examples: Roller marks are not uncommon on large coins of the 19th century, such as Morgan Dollars.
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