Collar Clash (CCL)
A collar clash is damage to the rim gutter of a die caused by contact with the collar. The rim gutter is the recessed area on the die face surrounding the main design that forms the raised rim on the struck coin. When a misaligned die contacts the collar — either through lateral displacement or vertical misalignment — the collar's working surface impresses marks into the die's rim gutter. On coins struck from an affected die, these marks appear as raised serrations, grooves, or linear marks along the top or inner edge of the design rim.
Collar clashes are far more common on the hammer die (the upper die that descends during striking) than on the anvil die.
How Does It Happen?
The collar is a cylindrical sleeve that sits at the level of the press bed, forming a chamber around the lower (anvil) die. During striking, the planchet is placed inside the collar, and the upper (hammer) die descends to strike the coin. On reeded-edge coins, the collar's interior surface carries grooves that form the reeding on the coin's edge.
Collar clashes form through two primary mechanisms, depending on which die is affected:
Hammer Die Collar Clash (Most Common)
When a misaligned hammer die temporarily collides with the top edge of the collar or scrapes along its working face during the striking cycle, the collar's surface impresses marks into the hammer die's rim gutter. This occurs when:
- The hammer die is laterally displaced from its proper alignment, causing its rim area to contact the collar during descent
- Mechanical vibration or worn guide components allow the hammer die to shift during the strike cycle
- The die descends at a slight angle, bringing one side of the rim gutter into contact with the collar
Anvil Die Collar Clash (Less Common)
Two mechanisms can produce collar clash on the anvil (lower) die:
- Scraping action: Repeated up-and-down movement causes the die neck to scrape against the collar's working face, impressing collar marks into the die's rim area
- Sideways impact: A sharp lateral force drives the die neck into the collar's working face, creating a single-event impression
How to Identify a Collar Clash
Collar clash marks have a distinctive appearance:
- Location along the design rim: Collar clash marks appear on or near the raised rim of the coin, in the area corresponding to the die's rim gutter. They are confined to the peripheral zone where the die face meets the collar during a clash event.
- Serrations on reeded coins: On reeded-edge denominations (dimes, quarters, halves, dollars), collar clash marks appear as serrations along the top or inner edge of the design rim — raised parallel lines matching the width and spacing of the coin's edge reeding. This is the most recognizable form of collar clash.
- Grooves in the slide zone: On off-center strikes that also exhibit collar clash, the marks manifest as parallel grooves in the "slide zone" — the area where the die scraped across the collar during its misaligned descent.
- Consistent from coin to coin: Every coin struck by the affected die carries identical collar clash marks in identical positions. Finding multiple coins with matching marks confirms the die origin.
- Specific clock position: Collar clash marks appear at the specific rotational position where the die-collar contact occurred — they do not encircle the entire rim.
Collar Clash vs. Similar Phenomena
Machine doubling takes several forms, and worn dies produce a look-alike of their own; Mechanical Doubling covers the whole family.
| Feature | Collar Clash | Standard Die Clash | Machine Doubling | Post-Mint Damage |
|---|---|---|---|---|
| Location | Along design rim only | In fields (design from opposite die) | Across design elements | Random |
| Pattern | Serrations or parallel grooves matching reeding | Recognizable design from opposing die | Flat shelf displacement | Irregular scratches |
| Cause | Die rim gutter contacts collar | Dies strike each other without planchet | Die bounce during ejection | Handling damage |
| Consistency | Same on every coin from that die | Same on every coin from that die pair | Varies coin to coin | Unique to individual coin |
Notable Examples
1997-P Roosevelt Dime
Error-Ref illustrates a 1997-P dime whose collar clash runs from about the K8 to the K12 clock position, showing reeding-width serrations along the design rim.
Kennedy Half Dollar Collar Clashes
Error-Ref also shows a 1980-P Kennedy half dollar with collar clash marks from about the K7 to the K11 clock positions on the obverse.
A Clashed State Quarter Hub
Error-Ref shows a defaced state quarter working hub that carries evidence of an earlier collar clash. Its face had been ground down to the level of the rim gutter, and some of the clash grooves survived; they match the width and spacing of a quarter's reeding.
Collecting Tips
- Reeded-edge coins show the clearest marks: The parallel serration pattern transferred from a reeded collar is immediately recognizable. Reeded-edge denominations (dimes, quarters, halves) show the most distinctive collar clash marks.
- Directional lighting is essential: Collar clash marks are low-relief features that can be difficult to see under flat lighting. Use a strong directional light at a low angle to the coin's surface, rotating the coin slowly to catch the raised serrations casting shadows.
- Check the rim area systematically: Examine the full 360 degrees of the rim area on both sides. The clash marks appear at specific clock positions where the die-collar contact occurred — not around the full circumference.
- Distinguish from edge reeding: Collar clash serrations appear on the flat face of the coin near the rim, not on the edge itself. Normal reeding is on the edge; collar clash transfers that reeding pattern onto the die face.
- More common on hammer die: Error-Ref reports collar clashes far more often on the hammer die than on the anvil die, so check the side of the coin struck by the hammer die first.