Roller marks are evident on this 1851-S Morgan Dollar on the part of the coin which was softest-struck: on the ear and the locks of hair above the cheek. Diagnostics that help define these roller marks are:
- The lines are straight and parallel.
- Lines are too deep to be slider marks, too straight to be cleaning.
- Lines appear only on weakly struck area of the coin, (positive trait for roller marks, although you would hope to see them in the field too.)
- Adjustment marks weren't made this late, so rule them out.
This specimen isn't as cut-and-dried as some others, but by ruling out other possibilities, and recognizing the distinctive look of roller marks, this determination can be made with confidence.