The 1990 No S DCAM Lincoln Cent is one of the most famous modern errors in American numismatics.
This coin is a Lincoln penny struck in 1990 as part of an official United States proof set.
Proof coins from this era were made at the San Francisco Mint and should always carry an "S" mintmark below the date.
Workers at the Philadelphia Mint prepared the dies for proof production back then, and they had to punch the mintmark by hand.
A worker accidentally missed adding the "S" to at least one obverse die before sending it to San Francisco.
The San Francisco Mint used that die to strike proof pennies, creating a proof coin that looked like an unmintmarked Philadelphia issue.
These pieces were packaged into standard proof sets and shipped out to collectors before anyone noticed the mistake.
The DCAM designation stands for Deep Cameo, which means the design has heavy, frosted details that pop against deeply mirrored fields.
One exceptional example of this error achieved a notable record through the auction house BM.
The coin crossed the auction block for 8/07.
Grading services certified this specific piece at a stunning grade of 69.
Coin grading uses a standard 70-point scale where a grade of 70 represents absolute perfection.
A grade of 69 means the coin is nearly flawless to the naked eye and under low magnification.
It can only have tiny, microscopic imperfections that kept it from reaching the top grade.
Top-tier collectors compete fiercely whenever a specimen this close to perfection appears at public auction.
The sale through BM proved that elite collectors will pay top dollar for the finest known modern errors.
Most error coins come from regular circulation strikes, but major proof errors are exceptionally rare.
Proof coins go through strict quality control checks at every stage of production.
Inspectors catch almost every defect before proof sets ever leave the mint facility.
Because the mint caught the mistake early, only a small number of these coins ever reached the public.
The surviving population of the 1990 No S penny remains extremely low.
Lincoln cents also happen to be the most popular coin series to collect in the United States.
Thousands of collectors try to build complete date and variety sets of Lincoln cents.
When high collector demand meets an extremely tiny supply, market prices climb quickly.
Finding one in Deep Cameo condition with a grade of 69 makes the coin even more desirable.
You can check your own coins by following a few simple steps.
First, look closely at the area directly beneath the 1990 date on the front of the coin.
A magnifying glass or a 10x jeweler's loupe will give you the clearest view of the surface.
Make sure the coin has a mirror-like, reflective background and frosted, matte lettering.
Do not confuse this rare error with an ordinary 1990 penny found in everyday pocket change.
Regular 1990 pennies struck for circulation in Philadelphia naturally lack a mintmark and have standard flat surfaces.
The valuable error only exists as a proof strike, which came originally from a plastic-cased proof set.
If you have trouble telling a proof strike apart from a shiny pocket change coin, you can use an app like Coin Value Checker or CoinKnow to help scan the piece.
Keep in mind that high auction records belong only to certified, ultra-high-grade specimens.
If your coin shows true proof finishes with no "S" mintmark, you should have it evaluated by a professional grading service.
For the shortest route from coin to price, see a closer look at which coin valuation app actually works.