The list of explanations for elevated, linear imperfections on
coins is lengthy. Die scratches, die gouges, die scrapes, die dents,
die cracks and plating blisters account for many raised, linear defects.
One category that is rarely encountered is a blemish that arises
from debris trapped between a working hub and a working die during the
Each working die is fabricated through a process known as hubbing.
A working hub, which carries a raised, normal-sized, normally oriented
version of a coin’s design, is slowly forced under enormous pressure
into a blank working die. The working die is left with an incuse
(sunken), mirror-image version of the design. When the working die
strikes a planchet, the normal raised design is formed on the newly
The working die is annealed (heat-softened) prior to hubbing so
that its surface metal can flow around the raised devices on the face
of the much harder working hub.
The hubbing press is kept scrupulously clean, as even a small
speck of foreign material that intrudes between the working hub and
the working die will mar the latter. Yet, every once in a while
foreign matter does find its way into this sanitary environment.
Robert Piazza recently sent me a 1943 Lincoln cent with a long,
thin, slightly sinuous ridge on the obverse face. It appears to
represent the impression of a filament, perhaps metal, perhaps nylon.
The ridge begins at the internal margin of the design rim and
immediately passes through the right side of the R of TRUST. It then
crosses the field and enters Lincoln’s bust. It passes through
Lincoln’s face and neck before fading out near the bottom of his
shoulder. Until this final fade-out, the ridge shows no change in its
diameter or relief.
A few very faint, very thin, relatively short subsidiary ridges
extend from the main ridge. These suggest that the filament
responsible for the corresponding groove in the working die was frayed.
Piazza’s coin shows only slight hints of wear and carries only a
few minor rust spots. The surface otherwise retains the original zinc
coating of the galvanized steel planchets used for this one-year
issue. This is important, as many steel cents were replated
(“reprocessed”) with zinc in the post-war period for the collector
market. It’s theoretically possible for debris to become trapped
between the coin’s original surface and the secondary layer of zinc.
I suppose it’s also possible for debris to have clung to the steel
cent strip before the original zinc coating was applied. However, any
foreign matter trapped between zinc and steel at this point would have
been driven into the planchet by the impact of the dies and would lie
at the same level as the field and design.
The uniform clarity and dimensions of the ridge support the idea
that this represents a piece of hubbed-in debris. A filament trapped
between working hub and working die would be forced to conform to the
newly-impressed recesses of the working die, producing a uniform
incuse trace that wouldn’t skip any portion of the field or design.
Other causes of raised linear blemishes are less likely.
Accidental gouges and dents in the working die face primarily or
exclusively affect the field portion of the die. This is because the
field is particularly vulnerable to damage while die recesses are
relatively protected. In those rare cases where a gouge does extend
into the design, it almost always appears on the coin with a reduction
in height and width.
Die cracks are variable in their appearance but generally follow a
straight path or assume a somewhat jagged trajectory. One thing a die
crack will never do is follow a gently sinuous course like that seen
in the 1943 cent.
Die defects are repetitive, appearing on every coin that the die
strikes. Therefore, I fully expect some other 1943 Lincoln cents have
this same ridge. If any Clearinghouse reader happens to stumble upon
one, please let me know.
Before concluding, I should mention that superficially similar
raised lines can be found on silver and copper coins, many dating from
the 19th century. However, these lines represent acts of vandalism.
Individuals would drag a sharp blade through the coin’s surface at a
low angle, lifting up a narrow flap.” When the flap was pressed down,
either intentionally or in the course of circulation, the incision
would be hidden and all you’d have left is a sharply defined ridge.
Coin World’s Collectors’ Clearinghouse department does
not accept coins or other items for examination without prior
permission from News Editor William T. Gibbs. Materials sent to
Clearinghouse without prior permission will be returned unexamined.
Please address all Clearinghouse inquiries to email@example.com or to
800-673-8311, Ext. 172.