The San Francisco Mint struck special proof Lincoln cents for collectors in 1978.
These pennies were never meant for regular pocket change.
Mint workers made them using polished blanks and specially prepared dies.
The 1978-S proof penny features a sharp strike with deeply mirrored fields.
Deep Cameo examples stand out because the raised design elements show a heavy, frosted white contrast against those dark mirrors.
By 1978, the mint had improved its methods for producing these dramatic proof coins.
Even with better technology, finding one with zero flaws remains very tough.
A top-graded example of the 1978-S DCAM Lincoln cent brought an eye-catching price at public sale.
Heritage Auctions sold this standout coin in June 2008 for $4,313.
Professional coin graders certified the piece at a perfect PR-70 Deep Cameo.
A grade of PR-70 is the highest possible score a proof coin can ever receive.
It means the coin shows no contact marks, hairlines, or production flaws under 5x magnification.
Serious collectors will pay huge sums to own an example that achieved absolute technical perfection.
Millions of proof sets were made in 1978, so regular proofs are easy to find for just a few dollars.
The high value comes entirely from condition rarity.
Making a PR-70 Deep Cameo required flawless die preparation by the mint team.
Fresh dies gave the heavy frost on the letters and portrait, but that frost wore down quickly as more coins were struck.
Careful handling was also needed at every step so the coin never picked up a single hairline or spot.
Most 1978-S proofs have tiny planchet defects or faint marks from packaging.
Those small flaws keep the vast majority of surviving coins in PR-68 or PR-69 holders.
When a coin crosses the line into a PR-70 holder, intense competition between registry set collectors drives the price up.
You can start your search by looking at the date area on the front of the penny.
Find the year 1978 and look directly below it for the small "S" mint mark.
Regular 1978 pennies made for circulation in Philadelphia have no mint mark, while Denver coins show a "D".
Check the surface finish next to confirm you have a proof coin rather than a shiny regular strike.
A proof has glass-like, reflective background fields.
To qualify as Deep Cameo, Abraham Lincoln's bust and the lettering must have a thick, frosted texture that contrasts sharply with those fields.
Use a 5x or 10x jeweler's loupe to scan the entire surface for tiny spots, scratches, or cloudy patches.
Any visible flaw under magnification means the coin will not grade at PR-70.
If you are not sure what you have, you can use Coin Value Checker on your phone for a quick first check.
Keep in mind that raw coins from old sets almost never reach the perfect grade needed to match record auction prices.
If you want confirmation without a dealer visit, see this comparison of every free coin identifier apps worth trying.
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