Error Coin Checker

Two kinds of doubling look alike. A doubled die shows rounded, separated second images, because the die itself was made with two impressions. Machine doubling shows flat, shelf-like doubling caused by a loose die bouncing during the strike. It adds no value.

1. Look at the doubling under 5x to 10x magnification
2. Rounded and separated: likely a doubled die, check the variety lists
3. Flat and shelf-like, on one side only: machine doubling

Learn more: Doubled Die · Machine Doubling (Strike Doubling)

An off-center strike happens when the blank sits out of position between the dies. Collectors value them by how far off center they are and whether the full date still shows.

1. Check that part of the design is missing and that blank metal shows, flat and untouched
2. Make sure the date is visible
3. A raised rim that wanders, or a smeared design, points to damage instead

Learn more: Off-Center Strike

A clipped planchet comes from the blank being punched where the metal strip overlapped a hole already cut. Genuine clips show a soft, tapered edge and a weak spot in the design opposite the clip.

1. Look for the tapered, slightly blurred edge of the clip
2. Look for weakness in the design across from it (the Blakesley effect)
3. Sharp, shiny, straight cuts are almost always done with tools

Learn more: Clipped Planchet

A copper-colored face on a dime, quarter or half can be a missing clad layer. A coin in the wrong metal entirely can be a wrong planchet error. Most color problems, though, come from chemicals, heat or plating after the coin left the Mint.

1. Weigh the coin: wrong planchet and missing layer errors have a different weight
2. Check that the design is sharp everywhere; plated or chemically altered coins look soft
3. Look at the edge for a layer that is missing or uneven

Learn more: Missing Clad Layer · Wrong Planchet Error · Post-Mint Damage (Not an Error)

Raised lines are die cracks and raised blobs at the rim are cuds, both made when a die breaks. They add interest and a small premium on most coins, more on popular dates.

1. Check that the line is raised, not cut into the coin
2. A blob that joins the rim is a cud
3. Scratches and gouges are sunk into the surface and are damage

Learn more: Die Crack and Die Break (Cud) · Die Clash

A mirrored, sunken copy of one side on the other side is a brockage, made when a struck coin stuck to a die. These are scarce. Faint outlines of the other side's design can also be a die clash.

1. Check that the sunken image is a mirror image
2. Compare the edges: brockages keep a normal rim
3. Coins pressed together in a vise show flattened rims and look crude

Learn more: Brockage · Die Clash

Repunched mint marks, overdates and missing mint marks come from how dies were prepared. Some are well-known varieties.

1. Look for a second letter or digit under the main one
2. Check the date and mint mark against the variety list for your coin
3. A mint mark that looks glued on or tooled is an alteration

Learn more: Repunched Mint Mark (RPM) · Overdate · Missing Mint Mark

Peeling metal can be a lamination error, where impurities made the metal split. On zinc cents, though, bubbles and peeling are corrosion of the copper plating and are not errors.

1. On a pre-1982 or silver coin, look for a layer lifting from the surface
2. On a zinc cent (1982 and later, 2.5 g), bubbling is corrosion
3. Struck-through errors show a crisp shape pressed into the design

Learn more: Lamination Error · Struck-Through Error · Post-Mint Damage (Not an Error)

Almost always damage after the coin left the Mint. Coins get run over, hammered, drilled and dropped in acid. None of that adds value.

1. A genuine error is made by the Mint's machinery and looks it: crisp, consistent metal flow
2. Cuts, gouges and dents with displaced metal are damage
3. If in doubt, compare with photos on the error type pages

Learn more: Post-Mint Damage (Not an Error)