The United States Mint had been minting proof coinage long before the introduction of the Lincoln
Cent.   Lincoln Cents proofs have been minted in three different forms:
Matte Proofs, Brilliant Proofs,
and Frosted Cameo Proofs.  Matte proofs were minted from 1909-1916.  The U.S. Mint did not strike
any official proofs from 1916-1935.  1936 is the first year the United States began producing Proof
Sets which included the Brilliant Lincoln Cent proofs.  Brilliant Proof Lincolns were minted from 1936
-1942, 1950-1964, and from 1968 until the late 1970s.  As proof technology improved during the
1970s, the mint began producing proofs with a more cameo appearance.  Cameo proof coins are is
described as having frosted devices and mirrored fields.  The devices of a coin are any raised
element of design.  The fields are flat portions of the coins surface.  The contrast between the frosted
devices and the mirrored fields is appealing to collectors of proof coinage.   Before the late the '70s,
cameo proof Lincolns were scarce, this was because only sharply struck examples made early in the
life of the die maintained a cameo appearance.  However, cameo proofs can be found as early as
1936.  As mint technology has improved, the Mint has been able to produce frosted cameo proofs
with regularity.  Before the late the '70s, cameo proof Lincolns were scarce, this was because only
sharply struck examples made early in the life of the die maintained a cameo appearance.

Modern proof coins with frosted cameo devices and mirrored fields are minted in the following way:  
Cent planchets are polished in a vibrating bowl of elongated steel pellets.  The planchets are hand
fed into the coin press one at a time.  Each planchet is struck two or more times using a slower speed
press with extra pressure to ensure a quality strike with high relief.  The dies used to strike the
planchets are specially prepared and also individually polished.  The devices and fields of the die are
separately treated to give the cameo appearance.   The dies are polished several times during their
lifespan and replaced frequently.  A proof die will strike far fewer coins than that of a business strike
die.  Planchets, dies, and proof coinage will undergo more inspection by mint employees than
business strikes.  Proof coins are never touched by human hands.  Mint employees use gloves when
handling proofs.  Once the coins are minted and inspected, mint employees assemble each proof set
by hand.  Each proof set is sonically sealed in plastic holders.    

Lincoln cent proofs have been minted at two different mints.  All Lincoln cent proofs from 1909-1964
will have no mint mark.  These were minted at the Philadelphia mint.  From 1968 on, Lincoln cent
proofs bear an “S” mintmark because they have been minted at the San Francisco Mint.  

Errors and varieties are far less likely to be seen on proof coinage.  This is due to increased
inspection, lower mintages, and a more precise minting process.  However, varieties and errors can
be found.   The 1990 No S Lincoln Cent Proof is a best example of a mint mistake that has resulted in
a very popular and expensive variety.  Repunched mintmarks and doubled dies have also been seen
in Lincoln Cent proof coinage.   

Proof coins are graded similarly to business strikes.  The term proof does not refer to the condition of
the coin, but rather the process used to strike the coin.  Uncirculated business strikes are given the
abbreviation MS for Mint State.  Proof strikes are given the abbreviation PR for Proof.  Like business
strikes, proofs are graded on a scale from 1-70.  Only proofs that have somehow reached circulation
and show signs of wear will receive grades below 60.  Most proof coins will grade between PR60 and
PR70.  A PR60 cent will have many marks at its surface will be less appealing to the eye.  A PR70
proof cent will be a perfect coin that is struck extremely well.  Since the cameo effect is so important to
proof collectors, coins can also be given a CAM or DCAM designation.  CAM stands for cameo, and
DCAM stands for deep cameo.  Some coins have also been given the designation Ultra Cameo.  
Proof Lincoln Cents
1936 - 1942, 1950 - 1964, 1968S – Present
Top image: 2008 S frosted cameo proof.      Bottom Image: 1960 Small Date Brilliant Proof.  
Images by Jason Cuvelier