What it is
A doubled die is a die that received two slightly misaligned impressions from the hub when it was made. Every coin struck from that die shows the same doubled lettering or design.
What causes it
Until the late 1990s, working dies were made by pressing a hub into the die several times. If the die shifted between pressings, it took on a doubled image. Modern single-squeeze hubbing has made doubled dies much rarer.
How to identify it
- The doubled elements are rounded and raised, with notches or "split serifs" where the two images meet.
- Every coin from the same die shows identical doubling.
- Doubling usually appears on lettering and dates near the rim.
How to tell it from damage
Machine (strike) doubling looks like a flat, shelf-like ghost beside the letters and is worthless. See our page on machine doubling.
Famous examples
Where in die making a doubled die forms
A doubled die is born in the die shop, long before any coin is struck. A working die starts as a steel blank with a slightly cone-shaped face. It is pressed against a hardened working hub that carries the design in relief. The design sinks into the die face. Under the older multiple-hubbing method, one squeeze could not move enough steel to bring up the full design, so the die was removed, annealed to soften it again and returned to the hubbing press for a second and sometimes a third squeeze.
Each time the die went back into the press it had to line up exactly with the impression already in it. A tiny rotation, a slight tilt or a shift of a fraction of a millimeter was enough to give the die two overlapping images. Because the doubling is in the die itself, it is copied onto every coin that die strikes until the die is retired, which can mean hundreds of thousands of identical error coins.
In the 1990s the Mint moved to single-squeeze hubbing, in which one high-pressure squeeze fully forms the die. With no second squeeze there is no chance to misalign, so the dramatic doubled dies of the 1950s through the early 1990s have largely disappeared. Modern doubled dies still turn up, but they tend to be small spreads visible on only a few letters.
How collectors classify doubled dies
Specialists sort doubled dies into eight classes based on how the second image relates to the first, a system used by CONECA, the main error and variety club in the United States. Class I, rotated hub doubling, turns the second image around a point near the center of the die, so the spread grows toward the rim. Class II, distorted hub doubling, comes from hubs that differed slightly in shape and shows stretching toward the rim. Class III, design hub doubling, happens when a die receives impressions from two different hub designs. Class IV, offset hub doubling, shifts the whole image in one direction.
Class V, pivoted hub doubling, rotates the image around a point near the rim. Class VI, distended hub doubling, thickens design elements rather than splitting them. Class VII, modified hub doubling, involves a hub that was altered between squeezes. Class VIII, tilted hub doubling, comes from a hub that met the die at an angle, so the doubling is strong on one side and fades across the coin.
Doubled dies are also labeled by side: DDO for a doubled die obverse and DDR for a doubled die reverse. Each known die receives a catalog number in references such as the Cherrypickers' Guide (which uses FS numbers) and the CONECA master listing. Two coins with the same date and mint can therefore be told apart by which die struck them.
Documented doubled dies worth knowing
The 1955 doubled die obverse cent from Philadelphia is the classic, with a wide spread on the date, LIBERTY and IN GOD WE TRUST that is easy to see without magnification. The 1972 Philadelphia doubled die obverse cent shows strong doubling on the same legends and the date. The 1969-S doubled die cent from San Francisco is far scarcer. The 1995 Philadelphia doubled die obverse cent has a smaller spread, seen best on LIBERTY and IN GOD WE TRUST.
On the other side of the coin, the 1983 doubled die reverse cent shows doubling on ONE CENT and the legends around the Lincoln Memorial. The 1984 doubled ear cent shows a second earlobe below Lincoln's ear. Every one of these dies was made before single-squeeze hubbing, which is why variety hunters concentrate on older dates when they search rolls.
A step-by-step check for a suspected doubled die
Start by looking up the date and mint in a variety reference, which tells you exactly which letters and numerals to examine. Under a 5x to 10x loupe and a single bright light, study the edges of those elements. A real doubled die shows two images with rounded tops. Where they overlap you will see notches at the corners of letters, often called split serifs.
Next compare the coin with photos of the listed die and check the pickup points, small markers such as polish lines, die cracks or a die chip that identify that particular die. If the direction of the spread and the markers match, you have a match. If the coin matches nothing listed, it may be a new die or something else entirely, so treat it with caution until an attributor confirms it.
Finally rule out the common mimics. Machine doubling leaves a flat, shelf-like step. Die deterioration doubling leaves a fuzzy halo around letters on coins from worn dies. Split plating doubling on copper-plated zinc cents is simply plating that has lifted at the edge of a letter.
Why doubled die doubling cannot be added later
Doubled die doubling is struck metal. Both images were formed by the same die in the same blow, so they share the coin's luster and flow lines and the second image rises close to the height of the first. Nothing done to a coin after it leaves the Mint can create a raised second letter, because tools can only cut, push or flatten metal. Damage always lowers part of the design. It never builds up a precise new letter beside an old one.
How doubled dies are graded and attributed
Major grading services attribute listed doubled dies on the holder label, usually with the catalog number, when the submitter asks for variety attribution. Minor doubled dies may only be recognized by specialist attributors. The strength of the spread matters as much as the grade. A coin from an early die state, struck while the die was fresh, shows sharper doubling than a late die state coin from the same die after wear has softened the details.
Frequently asked questions
What causes a doubled die?
Until the late 1990s, working dies were made by pressing a hub into the die several times. If the die shifted between pressings, it took on a doubled image. Modern single-squeeze hubbing has made doubled dies much rarer.
How can I tell a doubled die from damage?
Machine (strike) doubling looks like a flat, shelf-like ghost beside the letters and is worthless. See our page on machine doubling.
How do I know if my coin is a doubled die?
Look for raised, rounded second images with notches where the two images meet, then match the coin to a listed die using pickup points in a variety reference. Flat, shelf-like doubling is machine doubling, not a doubled die.
Are doubled die coins still made today?
They are much rarer since the Mint adopted single-squeeze hubbing in the 1990s, but minor doubled dies are still found on modern coins. Big, easy-to-see spreads like the 1955 cent come from the older multiple-hubbing era.
What do DDO and DDR mean on a coin?
DDO means doubled die obverse and DDR means doubled die reverse. The abbreviation tells you which side of the coin carries the doubling.