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Part V. Planchet Errors:


Alloy errors

Subsurface Corrosion (CW 12/21/15)

    • Plated coins
      • Copper-plated zinc cents
    • Solid coins

Rolling Mill Errors

Blanking and Cutting Errors

Upset Mill Errors

    • Coins struck on blank (“Type I planchet”)
    • Abnormally weak upset (ES July/August 2005)
    • Abnormally strong upset (best seen on off-center strikes)
    • “Groovy edge” (possibly from worn groove in upset mill)
    • Variation in cross-sectional shape of rim/edge junction of planchet
    • Struck coin sent back through upset mill
    • Abnormal upset (ES Sept/Oct 2005; CW 2/27/12, 11/21/16)
      • Wide, flat edge
      • Smoothly convex edge
      • Abnormally wide proto-rim
    • Squeezed-in debris (upset mill inclusion) (ES May/June 2006; CW 9/6/10)
      • Foil-like metal wraps around edge onto one or both faces
        • e.g. Copper foil on nickels (not from improper annealing)
      • Metal wire wraps around edge onto one or both faces
      • Pellet embedded in edge (CW 9/6/10, 9/22/14)

Edge design errors (impressed into planchet before strike) (includes security edge errors) (CW 6/27/16)

    • Edge design missing
    • Edge design present on normally plain edge (CW 6/27/16)
    • Wrong edge design
    • Edge design too high or too low
    • Interrupted edge design
    • Tilted edge design
    • Broken edging die (CW 6/27/16)

Mispunched center holes (foreign only) (CW 1/7/19)

    • Misaligned holes
    • Double punched center holes
      • One hole centered
      • Both holes misaligned
      • Overlapping holes
      • Totally separate holes
    • Irregular center holes
    • Abnormally small hole
    • Partial hole (from broken hole punch)
    • Circular Indentation (partial penetration)
      • Due to broken-off punch tip
    • Unpunched center hole
    • Hole punched in planchet meant for a solid coin

Annealing Errors

    • Improper annealing (due to excessive heat, prolonged exposure to intense heat, or excessive oxygen in annealing oven) (replaces “sintered plating” and “copper wash”) (ES July/Aug 2010; CW 11/30/09, 2/8/10)
      • Black, brown, red, coppery discoloration (includes “black beauty” nickels)
      • Layer of copper, often peeling

Poorly annealed or unannealed planchets (hard, brittle planchets) (CW 3/14/11)

    • Broken planchets and coins (CW 3/14/11, 9/18/23)
    • Radial cracks in coin (usually struck out-of-collar)

Brittle coins (cross-classified with alloy errors) (CW 3/14/11)

Abnormally hard planchets (CW 12/17/12, 8/15/22)

On undersized or underweight planchets (CW 2/13/12)

Miscellaneous forms of mint discoloration

Plating Errors

Bonding/Bonding Mill Errors (ES, Sept/Oct 2002)

Irregular planchets

Pristine Planchets (i.e. lacking tumbling marks) (CW 1/11/16)

Pre-Strike Damage (CW 11/15/10, 11/15/10, 1/23/12, 1/30/12, 12/15/14, 4/13/15, 6/8/20)

    • COIN WORLD SPECIALS: articles posted HERE and HERE
    • Assay clips (cross-classified with blanking errors)
    • Rim burrs (CW 1/31/11)
    • Accidentally and intentionally “re-sized” planchets (CW 9/15/10)
    • “Crimp marks” (mostly found on off-metal errors, e.g., 5c/1c, 5c/10c)
    • Rockwell test mark in planchet (circular or oval dimple) (ES July/Aug 2006; CW 10/15/18)
    • Planchet with adjustment marks (gold and silver planchets filed to return heavy planchets to normal weight)
    • Edge rolled, squeezed, and folded-over (or with thin apron produced) (CW 11/15/10, 1/23/12, 6/15/20)
    • Pre-plating damage (zinc cents) (CW 1/23/12)
    • Post-plating damage (zinc cents) (CW 11/15/10)
    • Scraped-in debris (CW 2/23/15)
    • Repetitive pre-strike damage (CW 12/15/14)
    • Other forms of pre-strike damage
      • Gouged (CW 1/14/19)
      • Crushed (CW 4/13/15)
      • Scraped (CW 2/23/15)
      • Torn
      • Crumpled (CW 8/15/11)

Inter-strike Damage (CW 1/9/12, 8/20/12)

    • Cancelled or defaced between strikes (CW 3/25/13)

Trans-strike damage (CW 7/12/21)

Wrong planchet and off-metal errors

Bi-metallic errors (foreign only) (ES Nov/Dec 2005)

    • Misaligned core (ES May/June 2007; CW 3/6/23)
    • Misaligned center hole (ES Sept/Oct 2007)
      • Well-seated core (CW 3/6/23)
      • With misaligned core (CW 3/6/23)
    • Double-punched center hole
    • Unpunched center hole
      • Solid disc of ring metal (CW 3/26/18)
      • Solid disc of ring metal with embedded core
      • Solid disc of ring metal with core indent
    • Ring with incomplete punch (ES Sep/Oct 2007)
    • Core with incomplete punch
    • Struck outer ring (ES Jan/Feb 2007)
    • Struck core (ES Nov/Dec 2006)
      • From another denomination
      • From another country (ES Sep/Oct 2009, Nov/Dec 2011)
      • Struck by solid-denomination dies
    • Wrong core inserted (ES Sep/Oct 2013; CW 10/17/22)
      • Core-sized scrap disc of ring material inserted into disc
    • Wrong ring (ES March/April 2007; CW 10/10/22)
    • Ring accidentally punched from solid planchet
    • Ring accidentally punched from solid coin (ES Nov/Dec 2008)
    • Struck ring from another country (restruck)
    • Struck core from another country (restruck)
    • Unstruck core inserted into struck ring and then restruck
    • Abnormally small core (controversial)
    • Abnormally wide center hole (controversial)
    • Abnormally thin core
    • Abnormally thick core
    • Abnormally thin ring
    • Abnormally thick ring
    • Incomplete trilaminar core
      • Missing one layer (ES Mar/Apr 2010)
      • Missing two layers
    • Core punched out of ring strip
    • Ring punched out of core strip
    • Bi-metallic planchet struck by solid-denomination dies
    • Solid-denomination planchet struck by bi-metallic dies (ES Mar/Apr 2014)
    • Bi-metallic planchet struck by wrong bi-metallic design


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet

Part VI. Striking Errors:


Unstruck blank (“Type I”)

Unstruck planchet (“Type II”)

Die alignment errors

    • Rotated die errors (CW 6/21/10, 7/9/12)
      • Rotated die due to improper installation (fixed rotation)
      • Rotated die due to improper die preparation (fixed rotation)
        • (e.g., grinding flats in wrong spot)
      • Rotated die due to movement after installation (dynamic rotation)
      • Semi-stable rotated die errors (various causes)
        • Characterized by a limited range of motion, a limited number of positions, or the presence of a single dominant position (CW 7/9/12, 8/7/23)
    • Pivoted die errors (probably involves entire die assembly) (CW 6/22/15)
    • Horizontal misalignment (CW 10/27/03, 7/25/16)
      • Hammer die (CW 2/1/10, 6/25/12)
      • Anvil die (ES Sept/Oct 2004, March/April 2005; CW 9/27/10, 1/19/15, 1/4/21, 7/19/21)
        • With misaligned collar
        • With broken collar
      • Dynamic misalignment (CW 6/25/12)
      • Multiple misaligned strikes (CW 10/11/21, 11/29/21)
      • Stable misalignment
      • On double-struck coins
        • On first strike only (CW 8/31/20)
        • On second strike only (CW 5/19/08, 5/23/11, 9/9/13)
        • On both strikes
        • Alignment with off-center strikes (CW 8/19/19, 8/26/19)
    • Vertical misalignment (tilted die error) (ES Jan/Feb 2003, Sept/Oct 2003; CW 12/8/03, 12/20/10, 8/24/15, 10/24/16, 1/8/24)
      • Hammer die (CW 2/1/10, 6/17/13)
      • Anvil die
      • Dynamic misalignment (CW 10/24/16)
      • Stable misalignment (CW 1/29/14)
      • Associated with weak strike (? 2/1/10, 10/8/12, 8/16/21)
      • Associated with off-center strike (? 8/13/18)
    • Dual misalignments (both dies misaligned in different directions) (CW 11/28/11, 5/18/15, 1/9/17, 7/9/18)
    • Compound misalignments (CW 8/24/15)
      • Horizontal and vertical
      • Horizontal and rotated
      • Rotated and vertical
    • Forced misalignments (CW 8/28/17)

Collar alignment errors

    • Misaligned collar
      • Associated with misaligned anvil die
      • Associated with stiff collar error
      • Associated with elliptical strike clip
    • Rotating collar (detectable only when there’s a collar break and a multi-coin progression)

Collar deployment errors

    • Partial collar (CW 2/24/20)
      • Flange with bevel
      • Flange without bevel
      • Tilted partial collar
      • Undulating partial collar (CW 2/24/20, 7/25/22)
      • Re-entry partial collar
      • Incomplete ejection partial collar (CW 12/26/22)
      • Reversed partial collar (not an error)
      • Multiple steps (CW 3/15/21)
    • High deployment of collar with coin metal extruded beneath (doubtful)
    • Broadstrikes
    • Stiff collar errors (ES Nov/Dec 2000; CW 8/25/08)
      • Normal die installation
      • Inverted die installation
      • Association with misaligned dies
      • Association with misaligned collar
      • Strong collar scar
      • Strong collar scar with cupping
      • Planchet forced completely into fully deployed collar (“ram strike”) (ES Nov/Dec 2000, March/April 2001)
      • Elliptical strike clip (ES March/Apr 2000; CW 4/5/10)
      • Associated with weak strike (CW 2/11/13)
    • Collar shimmy (CW 8/21/17, 9/11/17)

Weak Strikes (ES Sept/Oct 2000; CW 5/3/04, 9/11/06, 6/18/07, 3/1/10, 5/23/11, 6/23/14, 8/27/18, 3/2/20, 10/26/20, 11/27/23)

    • Caused by insufficient die approximation
    • Caused by abnormally low ram pressure
    • Invisible strikes (ES March/April 2003, Nov/Dec 2003, March/April 2004, Nov/Dec 2006, May/June 2010; CW 5/3/10, 9/20/10)
      • With indent
      • With partial brockage
      • With struck-through error
    • Followed/preceded by strong strike (CW 7/13/20)
    • Stable series of weak strikes (CW 8/27/18)
    • Weak saddle strike
      • One strike weak, one strong (CW 4/8/13)
      • Both strikes weak (CW 12/12/11)
    • In combination with other striking errors
    • Rim-restricted first strike (CW 3/1/10, 10/10/11, 1/11/16, 2/19/18, 9/23/19)
    • Rim-restricted second strike (CW 9/21/15, 2/13/17)

Skidding Coin Errors (CW 1/29/18)

Abnormally Strong Strikes

Stutter Strikes (ES Nov/Dec 2001, Sept/Oct 2007; CW 12/28/09, 7/25/11, 8/10/20)

    • Due to spasmodically collapsing or stiff collar (Type I)
    • Due to planchet flexion (associated with indents and brockages) (Type II)
    • Due to contact with bent planchet or coin (Type III)
      • On face struck by anvil die (CW 8/26/13)

Concentric strike lines generated by a single strike (ES Jan/Feb 2012; CW 12/26/11)

Machine doubling (a.k.a. machine doubling, machine doubling damage, machine damage doubling, mechanical doubling, strike doubling, shift doubling, ejection doubling) (ES July/Aug 2006; CW 3/15/10, 7/24/17, 12/23/19, 3/30/20)

    • “Push doubling” (marginal shelving and sharp interior duplication) (CW 1/9/23)
    • “Slide doubling” (smeared design) (CW 8/14/17)
    • Rotational machine doubling (CW 8/10/15)
    • Intermediate forms
    • Multiple machine doubling in one direction (two, three, and four offset ranks)
    • Machine doubling in more than one direction (up to three directions)
    • Machine doubling on both faces of same coin (CW 3/15/10, 12/23/19)
    • Rim-restricted design duplication (see separate category)
    • Affecting incuse design elements (CW 2/6/06, 1/16/12)
    • Located on top of die break
    • Located on top of die attrition error (CW 4/14/14)
    • On out-of-collar strikes (rare) (CW 11/25/19, 11/21/22)

Rim-restricted design duplication (form of machine doubling) (CW 10/6/03, 2/22/10, 5/24/10, 12/6/10, 5/13/13, 12/30/13, 3/8/21, 4/12/21)

    • 2004 cent (ES March/April 2007; CW 2/22/10)
    • 1994 cents (CW 5/24/10, 8/22/11)
    • 1981-P quarter and 1979-D dime (CW 12/30/13)
    • Presidential dollars (ES Sept/Oct 2007; CW 2/22/10, 12/6/10)
    • Foreign coins (CW 2/22/10)
    • On face struck by anvil die (CW 10/21/13, 7/20/20)
    • Bifacial (7/20/20)
    • In conjunction with push doubling (CW 12/6/10, 7/20/20)

Ejection Doubling (CW 11/7/22)

Skidding Die Errors (CW 8/15/16, 11/27/17)

    • Skidding misalignment
      • Two-stage (CW 4/13/20)
    • Design decapitation error (top of design scraped off)
    • Slide doubling (see Machine Doubling)
    • Design ablation error (design scraped off by die movement on 2nd strike) (ES March/April 2008, Jan/Feb 2011; CW 9/13/10)
    • Combined with tilted die (CW 9/27/21)
    • From broken die (CW 7/26/21)

One-sided double-strikes (ES March/April 2000, Jan/Feb 2002, July/August 2003)

    • Hammer die rotated (CW 11/29/10)
      • Instantaneous
      • Gradual
    • Hammer die misaligned (CW 5/19/08, 5/23/11, 9/9/13, 3/8/21, 4/24/23)
      • Instantaneous
      • Gradual
    • Anvil die misaligned (CW 9/9/13)
    • Anvil die rotated (at least one known example, a proof Kennedy half dollar)
    • Rotated, with rocking die (CW 5/25/20)
    • False one-sided double strikes (CW 11/29/10)

Flat Field Doubling (imperfectly aligned proof strikes) (CW 4/29/13)

Off-center strikes

    • Cupped off-center strikes
      • With collar scar
      • Without collar scar
    • Uniface strikes
    • Stretch strikes
      • Uniface
      • Die struck on both faces (covered under high pressure strikes)
      • With unexplained, flat dent at opposite pole (not a “sideneck strike”)

Chain strikes (CW 4/12/10)

    • Normal chain strikes with straight edge
    • External chain strikes (ES Jan/Feb 2003)
    • Concave, convex, sinuous, and irregular chain strikes (ES Jan/Feb 2001, July/August 2002; CW 4/12/10)

Foreign Object Chain Strike (CW 5/25/15)

    • Chain strike against feeder

Machine Part Impingement (CW 5/25/15)

    • Bilateral
    • Unilateral

Saddle (Tandem) Strikes (CW 6/27/11)

    • Hump present
    • Hump absent
    • Inverted hump (hump points toward reverse die) (CW 9/19/16)
      • Buckling toward anvil die
      • Due to inverted die setup
    • Die position
      • Head-to-head
      • Head-to-base (early to mid- ’70s, mainly)
      • Face-to-back
    • Gap between adjacent dies
      • Narrow
      • Wide
    • With inverted die installation
    • Sideneck strikes (“one-die saddles”) (Expanding planchet collides with side of die neck) (CW 5/30/11)
    • On quarter dollars (CW 12/9/19)

Broadstrikes

  • (covered under collar deployment errors)

Split Plating Doubling

Foldover Strikes (ES July/August 2007; CW 10/10/05, 8/15/11, 1/30/12, 9/15/14)

    • Out-of-collar
    • In-collar
    • With edge strike persisting
    • On struck cents (normal and error)
    • Double foldover strikes (“Z-fold”)
    • Axial fold
    • Paraxial fold
    • Inward fold
    • Outward fold

Edge Strikes (CW 7/18/11, 10/12/15, 3/1/21)

Extrusion strikes (an effect, not an independent error) (ES March/April 2004; CW 10/24/11, 1/15/18)

Multiple strikes (CW 3/30/15)

Indents

    • In-collar/out-of-collar
    • Partial
    • Full (CW 7/30/12)
      • Centered
      • Uncentered
    • “Internal” indents (CW 11/1/10, 2/28/16)
      • On obverse
      • On reverse
    • Multiple indents
    • Irregular indents
      • Produced by error coins
      • Produced by clipped planchet
    • Indent by smaller planchet (CW 5/19/08)
    • External disc impressions (CW 3/18/19)
    • Unexpectedly shallow indents (CW 12/28/20)

Brockages

    • Full
      • Centered
      • Uncentered
      • Rotated (relative to die-struck design on opposite face)
    • Partial
      • Conventional
      • Aligned partial brockage (ES May/June 2005; CW 1/17/11, 12/5/22)
        • From partial die cap
        • From elliptical clip coin
        • From elliptical strike clip
      • Internal partial brockage (CW 11/1/10)
    • In-collar/out-of-collar
    • From another denomination (ES May/June 2005; CW 8/1/21)
    • From another error coin
      • From wrong planchet error (CW 11/28/22, 6/12/23)
      • From mangled and crumpled coins (often multi-struck) (CW 10/2/23)
      • From weakly-struck coins (CW 11/20/23)
    • Flipover brockage (CW 4/23/12)
      • On obverse
      • On reverse
    • First-strike brockage
      • “Mirror” brockage (unexpanded, undistorted) (CW 6/13/11, 3/17/14, 5/6/19, 10/28/19, 7/11/22, 6/27/22, 4/10/23)
      • Distorted first-strike brockages
    • Mid-stage and late-stage brockages
    • By struck fragment (CW 6/11/12)
      • Aligned with opposite, die-struck design
      • Not aligned with opposite design
    • From struck die fill (very rare) (CW 8/20/18)
    • From thin pieces of metal (CW 7/23/18)
    • From large dropped filling (CW 5/13/19)
    • Multiple brockages CW 9/26/11)
      • From multiple strikes
      • From clashed cap
      • From multi-struck coin (CW 7/4/22)
      • From more than one coin in striking chamber
      • From coin trapped between die cap and planchet
    • Clashed cap strikes (CW 8/30/10, 11/21/11, 1/13/14)
      • From a late-stage die cap that clashed with the opposite die
      • From a uniface die cap that clashed with the opposite die
      • From an early-stage die cap that clashed with the opposite die
      • From a cap that was striking counterbrockages that clashed with the opposite die
      • From a flipover die cap that clashed with the opposite die (CW 1/13/14)

Counterbrockages

    • Full (CW 10/11/10)
    • Partial (CW 11/8/10)
    • In-collar/out-of-collar
    • Counterbrockage of obverse on obverse
    • Counterbrockage of reverse on reverse
    • Flipover counterbrockage (CW 4/19/21)
    • Early, middle, and late-stage counterbrockages
    • From another error coin
    • Brockage-counterbrockage combination (8 types) (ES Nov/Dec 2009; CW 11/12/12)
    • Multiple counterbrockages (ES March/April 2010)
    • On second strike
    • Rebound counterbrockage (always on 3rd strike) (CW 11/9/15)
    • Secondary counterbrockage (CW 4/19/21)
    • Grease-generated counterbrockage (CW 4/11/22)

Horizontal lipping (CW 11/30/15)

    • In conjunction with in-collar indents, partial brockages, and struck-through errors

Die caps (CW 8/6/13, 1/7/20)

    • Hammer die caps (usually the obverse die)
      • Raised design on working face
      • Brockage on working face
      • Uniface die caps
      • Complex die caps
    • Anvil die caps (usually the reverse die)
      • Cupped toward anvil die, hammer die, both dies at opposite poles, or expanded in the horizontal plane
    • Partial (off-center) die caps (hammer or anvil) (CW 1/17/11)
      • With cupping
      • Without cupping
    • Detached cap bottoms (ES March/April 2001, May/June 2001)
    • Clashed caps (CW 1/22/24)

Capped die strikes (generic — without identifiable images)

    • Struck by uniface die cap
    • Struck through late-stage die cap
    • Struck through cap-like obstruction
    • Struck through split or torn cap
    • Proportional de-expansion (both faces struck through die cap or cap-like obstruction) (CW 11/11/13, 5/28/18)

Struck by impaled die cap (CW 6/10/13)

Capped die doubling (doubling associated with capped die strikes) (ES Sept/Oct 2005; CW 6/18/12, 5/16/22)

    • Shifted/rotated cap strikes (ES May/June 2000, March/April 2012; CW 11/21/11)
      • Correctly-facing incuse design elements (CW 11/3/08, 6/28/10, 6/11/12, 10/19/15, 8/12/19, 10/23/23, 11/13/23)
        • Multiple sets due to several preceding shift-and strike event
    • Unexplained, close raised doubling
      • Expansion ripples
    • Incuse doubling surrounding raised elements (CW 8/24/20)

“Struck-through” errors

    • Struck through fragment
    • Struck through clipped planchet (ES Sept/Oct 2002; CW 8/25/14)
    • Struck through thin struck fragment (CW 6/11/12)
      • Face-up (normally-oriented incuse design elements)
      • Face-down (mirror-image design elements)
      • Trapped between planchet and opposite die (mirror-image design elements)
    • Struck through detached lamination flake (CW 2/7/05, 6/11/12)
    • Struck through clad layer
      • Clad layer unstruck
      • Clad layer previously struck
    • Struck through reeding (CW 11/14/16, 8/21/23)
    • Struck through split planchet
      • Obverse
      • Reverse
    • Struck through hardware (bolts, screws, washers, etc) (CW 3/7/11)
    • Struck through feeder (ES Nov/Dec 2005; CW 3/7/11)
    • Struck-through unidentified machine part (CW 3/7/11)
    • Struck through emery disc (CW 12/16/02)
      • 1986 Silver Eagles struck through emery disc (CW 12/16/02)
    • Struck through “grease” (die fill)
      • Assorted ingredients, textures, viscosities, and consistencies (smooth, coarse, stiff, viscous, etc.)
    • Filled dies
      • Single design element (CW 6/29/20)
      • Multiple design elements
    • Struck through bulging die filling (CW 1/16/17, 5/20/19)
    • Filled collar/obstructed collar (ES Jan/Feb 2006; CW 9/22/14)
      • With flange
    • Surface Film Effects (ES May/June 2003; CW 8/16/10, 6/11/12, 10/29/12)
      • Surface film doubling
      • Surface film afterimage
      • Surface film transfer
      • Surface film transfer with clash marks
    • Dropped fillings (ES May/June 2003; CW 8/16/10, 6/11/12, 10/29/12)
      • Isolated elements (dropped letter, dropped number) (CW 2/7/05)
      • Conjoined dropped fillings (CW 8/16/10)
      • Large, multi-element dropped fillings (CW 4/19/10, 8/16/10, 11/14/22)
      • Retained dropped fillings
    • Struck through floating encrustation (on second strike) (CW 1/18/16, 6/18/18)
    • Yanked-out fillings (CW 1/16/23)
    • Struck through miscellaneous foreign matter
    • Field-restricted struck-through errors (CW 11/18/13)
    • Split or torn in two by struck-thru object (ES Nov/Dec 2007; CW 3/7/11, 7/13/15)
    • Retained struck-through errors (struck-in errors) (CW 7/18/16, 1/25/21, 9/13/21)
      • Embedded dropped filling (see above)
      • Embedded die fill (shapeless)
      • Die fragment (CW 2/6/23, 3/13/23)
      • Scrap metal
      • “Staple” (bristle from wire brush)
      • Plastic (associated with bullion coins)
      • Metal foil
        • (Cu-Ni)? associated with dimes and nickels)
        • Copper foil (ES Nov/Dec 2007)
      • Rubbery material (from die cover?)

Uniface strikes (cross-classified with indents) (CW 7/30/12, 9/16/19)

    • In-collar (CW 12/5/22)
    • On second strike (CW 11/29/10, 9/16/19, 6/5/23)
    • “Augmented” in-collar uniface strikes (CW 9/14/20)
      • Out-of-collar
        • Centered
        • Off-center

Sandwich strike (coin struck between two coins or planchets) (CW 5/16/11, 10/31/16, 11/20/17, 5/28/18, 3/22/21)

    • Partial
    • Full
    • Between two struck coins
    • Between two planchets
    • Between a coin and a planchet
    • Between struck coin and obverse die cap
    • Between obverse and reverse die cap

Nested coins (CW 3/16/20)

Mated pairs (CW 11/9/20)

Bonded coins

    • pile-ups (clusters)

Strike clips (ES July/Aug 1999, May/June 2001; CW 6/15/15)

    • Vertical shear clips (V)
      • Sheared between die and collar alone
      • Sheared between collar and overlying planchet
    • Horizontal shear clips (H)
    • Tensile strike clips (T)
    • Concave strike clips (V, H, T)
    • Elliptical strike clips (V, H ,T) (CW 4/5/10, 12/5/22)
    • Straight strike clips (H)
    • Saddle strike/strike clips (H)

Detached reeding

    • From forced broadstrikes
    • From stiff collar
    • Torn-off fin

Coin shrapnel (“breakaway fragments”)

    • Angular
    • Crescentic
    • Oval
    • Circular or sub-circular
    • Semilunar
    • Irregular

Intra-Strike Damage (damage coincident with strike) (CW 5/30/11, 12/20/21)

      • Flat contact facet at 6:00 opposite off-center strike
      • Machine part impingement on unstruck portion of off-center coin (CW 5/25/15)
      • Ejection damage to edge of unstruck perimeter.
      • External struck-through errors (with cupping) (CW 3/25/19)
      • Concave damage opposite off-center strike (12/30/19)

Cupping (CW 12/7/09)

    • With and without collar scar
    • In a single strike
    • Associated with multiple strikes
    • With die caps
    • Cupping toward hammer die
    • Cupping toward anvil die
    • Expansion in horizontal plane
    • On unobstructed strikes (CW 3/18/19)

Impact-Induced Warping (CW 3/16/15, 1/13/20)

Malrotation Errors (multi-sides coins only) (CW 3/23/15, 11/8/21)

Proof edge lettering errors (generated during strike by segmental collar)

    • Weak edge design due to segmented collar not closing fully (wide seams)
    • Segments arranged in incorrect sequence (see Die Installation Errors) (CW 4/7/08)


Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet

Partial Clad Layer Before Strike

PART V. Planchet Errors:

Bonding / Bonding Mill Errors:

Missing Clad Layer:

Partial: 

Before Strike

Definition: Part of the obverse or reverse clad layer is missing from the planchet.  Loss of cladding sometimes occurs before the clad strip is rolled to final coin thickness.  In such cases the coin weighs the same as a normal coin.  In other cases the cladding is lost after blanking but before the strike.  Such coins will weigh less than a normal specimen.

This 1999-P Washington Statehood quarter (Georgia) was struck on a planchet that was missing part of the clad layer on the obverse.

Images are courtesy of Heritage Auctions.

Peripheral Die Damage

PART IV. Die Errors:

Die Damage: 

Peripheral Die Damage


Definition: Peripheral die damage has many causes and results in marginal die loss. A die attrition error is a type of peripheral die damage (see Die Attrition Error).  The edge of the die can be chipped off or worn away as a result of accidental contact with the collar or other machine part.

Below are four examples of peripheral die damage.

A long strip of peripheral die damage on the right side of a 1983 Lincoln cent extending from 3:00 to 5:30 (obverse clock position). The internal border has a jagged appearance, but it is clear that it’s not due to a natural, spontaneous fracture. First of all, the design rim appears to be intact, which rules out a cud. Second, within the zone of damage there are numerous short, obliquely oriented ridges extending in from the rim and terminating in the field. These ridges are something you never see in cuds and are clearly the result of mechanical damage.

A second 1983 cent shows a similar case of peripheral die damage. Again, the design rim is intact. This indicates that the damage is restricted to the edge of the field portion of the die or, to put it another way, the medial wall of the rim gutter. Something has chipped or worn away this part of the die.

A third 1983 cent with loss of the outer portion of the field and its replacement by an incuse area of die damage. The cent probably represents a die attrition error. This curved groove is an unusual (but by no means unique) form of die damage and implies the presence of a thin burr extending down from the damaged portion of the die. It would be similar to the burr you get when you file down a piece of metal.
1983 cent with peripheral die damage on the reverse face by UNITED.

Peripheral Die Expansion And Erosion

Part IV. Die Errors:

Die Deterioration/Deformation Errors:

Peripheral Die Expansion and Erosion

Definition: This error is characterized by radial expansion of the die face, excluding the rim gutter.  The field portion of the die face and the peripheral design elements migrate outward, forming a thin shelf over the rim gutter that is immediately and continuously eroded.  The result is abrupt truncation of the peripheral letters where they crowd against the design rim.  This error has so far only been detected on some 1982 cents, but it probably more widespread.

Both faces of this 1982 cent show peripheral die expansion and erosion.  Observe how the outer portions of the peripheral letters are abruptly truncated where they abut the design rim.

Peripheral Doubling

PART II. Die Varieties:

Doubled Dies:

Single Squeeze Hubbing:

Peripheral Doubling


Very few doubled dies produced by the single-squeeze method show doubling of peripheral design elements. Most single-squeeze doubled dies exhibit doubling of elements near the center of the coin.  Two different scenarios
account for the dominance of the latter pattern.  Sometimes a working hub or a working die is not aligned properly.  When subjected to pressure, the hub or die will spasmodically settle into a more stable position.  That settling accounts for some centrally-located doubled dies.  In other cases, a squeeze is intentionally interrupted and the hub or die is re-positioned.  When hubbing resumes, a doubled die may result.

It’s not entirely clear why a few doubled dies produced by the single-squeeze method show peripheral hub doubling. While one or both scenarios mentioned above could play a role, it seems rather late in the hubbing process for this to be the case.

The images below show peripheral doubling affecting the motto “IN GOD WE TRUST” in a 2006(P) Lincoln cent.

Images are courtesy of Coppercoins.

Phantom Mintmark

PART II. Die Varieties:

Phantom Mintmark

Definition: A partial mintmark that has not been completely abrade and inadvertently left on a working hub.

This 1997 Lincoln cent minted in Philadelphia shows the remnants of a D mint mark. It has been surmised that the Philadelphia mint ran out of obverse dies and had to abrade the mintmark from a working hub to produce more working dies. The second upper image to the right shows the partial D mintmark indicated by the white arrow.

The lower left image is of a 1997 D Lincoln cent with that image being overlayed in the lower image to the right. When the two images are compared, the remnants of the D mint mark fall right in place of where that mintmark should have been.

PIDT On Dimes




PART
IV. Die Errors:


Die Deterioration / Deformation Errors:


Progressive Indirect Design Transfer:


On Dimes



Definition: This
is a lesser known form of die deterioration which transfers design
outlines from one die to the other. Since there are many types of design
transfer (clashed dies, brockages, etc.), it is preferable to call this type of
design transfer “Progressive Indirect Design Transfer” or
“PIDT”.  Other synonyms you’re likely to encounter are
“heavy design transfer” and “internal metal displacement
phenomenon (IMDP)”.

The 1946-D Roosevelt dime shown to the right has Progressive Inderect Design Transfer. Notice the outline of Roosevelt’s bust on the reverse of the coion. This anomaly is often confused with a die clash.


Pile Ups

PART VI. Striking Errors:

Pile-ups:

Definition: This error type occurs when  a die cap is formed on the hammer die. However, the one difference in this case from other die caps is that after striking of the new coin the coin is not ejected, but it is bonded by the striking pressure to the die cap mass.

The images below show a multitude of 1996-P Lincoln cents that have been fused together. This particular error was caused by a die cap forming on the hammer die. As a planchet was feed into the striking chamber, the hammer die would make contact with the planchet and fuse it into the mass. This particular “pile-up” of coins is refereed to as a “pine cone” since it does resemble that object.

This error comes to us from Mark Lighterman.

Pivoted Die Error

PART VI. Striking Errors:

Die Alignment Errors:

Pivoted die error


Definition: Any lateral misalignment greater than 10% is likely to involve the entire die assembly.  There just isn’t enough play in the hammer die’s recess to allow this sort of lateral movement.  Even if there was, the die would surely fall out.  It may be that most horizontal misalignments have nothing to do with a loose die and everything to do with an unstable die assembly.

If major horizontal misalignments can be caused by movement of the entire die assembly, then other sorts of lateral movements are also possible.  This 1983-D nickel shows a normal first strike and a possible pivoted die error on the second strike.  The obverse die was shifted to the left about 30% and rotated perhaps 20 degrees.  While this could be a combination of a horizontal misalignment and a rotated die error, it could represent a single movement of the hammer die assembly — a pivot.

In a pivoted die error, the obverse die seems to rotate around a vertical axis that runs along the side of the die shaft and may even occupy empty space lateral to the die shaft.  In actuality, the entire die assembly is pivoting.

As described above, pivoted die errors pose a diagnostic challenge. Unless the apparent rotation is greater than 45 degrees, any potential pivoted die error can also be interpreted as a combination of a horizontally misaligned and rotated die (or die assembly). It takes an unusual error to break this impasse.

This 1996-P quarter features a centered double strike, with a clockwise rotation of the coin between strikes. The first strike was in-collar while the second strike was out-of-collar (broadstruck). This coin also incorporates a counterclockwise pivot of the obverse (hammer) die between strikes.

As expected, primary and secondary design elements on the reverse face show a consistent rotational offset around the entire perimeter.

The date shows the same rotational offset. However, at the opposite pole, the primary and secondary letters of LIBERTY show a smaller amount of offset that shrinks as one moves from right to left. The first few letters of LIBERTY show no rotational offset at all.

This pattern could only have occurred if the obverse (hammer) die assembly had pivoted counterclockwise as the coin was rotating clockwise. The axis of rotation would have been located near 6:00. Owing to the pivot, the obverse design is shifted slightly more toward the southwest than the reverse is toward the northwest.