During the Second World War, the United States Mint changed how it made pennies.
The military needed copper for ammunition and equipment.
Because of that need, the mint switched to zinc-coated steel planchets for pennies in 1943.
A few leftover bronze blanks from 1942 remained in the tote bins and machinery at the mints.
The San Francisco Mint accidentally fed some of these old bronze blanks into the coin presses.
The result was the 1943-S bronze cent, an accidental off-metal strike that should not exist.
Only five genuine examples from the San Francisco Mint are known to survive.
That tiny number places this piece at rank 2 out of the 200 most valuable coins on our list.
Heritage Auctions handled the landmark sale of this particular bronze error.
The coin crossed the auction block in a November sale, cataloged as sale 11/20.
The professional grading service certified the piece at a grade of 63.
A grade of 63 means the coin is in uncirculated, Mint State condition.
It never saw everyday spending, but it may show a few small contact marks or light spots from storage.
Finding an off-metal error from 1943 that escaped heavy circulation is nearly unheard of.
A certified high grade removes all doubt about authenticity and gives collectors the confidence to bid aggressively.
Exceptional certified examples like this set the top market records.
The primary reason for the high value is absolute rarity.
With only five verified specimens from the San Francisco Mint, most advanced collections will never have one.
Steel pennies from 1943 are extremely common and easy to find in old collections.
Bronze pennies from that same year are famous throughout the collecting world as major mint errors.
Lincoln cents remain one of the most popular coin series ever collected in the United States.
When millions of people collect a series, demand for the rarest key issues becomes intense.
Every major collector of American errors or Lincoln cents dreams of owning a genuine 1943 bronze piece.
The combination of wartime history, an accidental mistake, and almost no surviving coins creates this massive value.
You should inspect any 1943 penny closely if it looks like standard copper or bronze.
The first test is simple and requires only a small magnet.
A normal 1943 steel cent will stick firmly to a magnet.
A genuine bronze error will not stick to a magnet at all.
Beware of plated steel pennies, because many people have copper-plated standard steel coins over the years.
A copper-plated steel cent will still stick to a magnet.
Another common fake involves altering the date on a common 1948-S cent by cutting away part of the eight to make it look like a three.
Use a 10x magnifying glass to check the date digits for tool marks, glue, or strange shapes.
You can also check the coin on a precise digital scale, where a bronze planchet weighs about 3.11 grams while a steel blank weighs about 2.7 grams.
If you are not sure what you are holding, a quick scan with the Coin Value Checker app can do the first pass for you.
The CoinKnow app is another helpful tool you can use on your phone to check coin details and spot obvious regular issues.
If your coin passes the magnet and weight tests, send it to a major third-party grading service for formal authentication.
Want to check a whole jar of coins quickly? the coin valuation app tools we tested side by side makes that practical.