Collar Clash

    A collar clash represents damage to the rim gutter of the die from contact with the collar.  It shows up most clearly in reeded issues, where it takes the form of serrations along the top or the edge of the design rim.  In an off-center strike, a collar clash will appear in the form of parallel grooves in the "slide zone".

    Collar clash is far more common on the hammer die.  It occurs when a temporarily misaligned hammer die collides with the top of the collar and/or scrapes along its working face.

    When collar clash occurs on the anvil die, it is probably from a repeated up-and-down scraping action of the die neck against the working face of the collar.  However, a sharp sideways impact that drives the die neck into the collar's working face could also produce this pattern of serrations.

Pictures courtesy of Koinmon and Jason Cuvelier