|United States proof coins
The U.S. had largely stopped striking proof coins in 1916,
although a few later specimens exist. Beginning in 1936, the
U.S. Mint began producing proof sets. Sets struck from 1936–42
(1942 offered a five-coin and a six-coin version, the latter
included the silver wartime nickel) and, when resumed, from
1950–72 include the cent, nickel, dime, quarter, and half
dollar. From 1973 through 1981 the dollar was also included,
and also from 2000 on. From 1950 to 1955, proof sets were
packaged in a box and each of the five coins was sealed in
a cellophane bag. 1955 saw both the original "box"
packaging and introduced the flat-pack, where the coins were
sealed in cellophane and presented in an envelope. The flat-pack
packaging continued through 1964, after which the coins were
sealed in various styles of hard plasticized cases. (From
1965 to 1967, the production of proof sets was suspended and
Special Mint Sets were made in their place. They were made
at the San Francisco Assay Office but bore no "S"
Beginning in 1999, proof sets also contain five different
Statehood quarters. The 2004–05 series also contain the two
Lewis and Clark nickels. Beginning in 2007, full proof sets
include the four Presidential dollars for that year; proof
sets of only Statehood quarters and Presidential dollars are
also available. Proof sets issued in 2009 contain 18 coins
– the most ever included – as that year marked the Lincoln
Birth Bicentennial and featured four different reverses for
the Lincoln Cent. These were struck in the original metal
composition of Lincoln Cents: 95% Copper and 5% Tin &
Zinc, which differs from the copper-plated zinc composition
of circulating Lincoln Cents used since 1982. Also included
were six quarters (instead of five) issued under the District
of Columbia and United States Territories quarters program.
2010 saw the introduction of the Lincoln Cent with new the
Union Shield reverse which replaced the familiar Lincoln Memorial
reverse used from 1959 to 2008. Also introduced for 2010 were
the first five of the new America the Beautiful quarters program,
depicting different National Parks and Monuments, one from
each state, Washington D.C. and the five U.S. Territories.
The U.S. Mint has also released
special proof sets, such as in 1976, when a proof set of
three silver-clad coins: the quarter, half-dollar and dollar
coins depicting special reverses to commemorate the U.S.
Bicentennial was issued. From 1971 to 1974, proof silver-clad
Eisenhower dollars were issued in a plastic case contained
in a brown wood-grain finish slipcase box, and are referred
to as 'Brown Ikes'. Proof Susan B. Anthony dollars were
struck in 1999, but were sold separately and not included
in the proof sets in that year. A proof "Coin &
Chronicles" set was issued for 2009, which included
one each of the 4 different Lincoln Cent designs and a commemorative
Lincoln Silver Dollar, presented in special packaging. Other
sets, called "Prestige Proof" sets, also contain
selected commemorative coins. These sets were sold from
1983 to 1997 (except 1985) at an additional premium. As
Legacy Proof sets, the practice was resumed from 2005 to
Occasionally, there are errors which escape the Mint's inspection
process, resulting in some very rare and expensive proof
sets. This has happened at least seven times: 1968-S, 1970-S
and 1975-S and in the 1983-S Prestige set, each with a dime
that has no mint mark; a small number of 1971-S sets included
a nickel without a mint mark; 1990-S saw both regular and
Prestige sets which included a penny with no mint mark.
Not quite so rare (or expensive) are proof sets issued which
vary from other sets issued in the same year. These include
the 1960 and 1970-S sets, both of which are found in either
a "small date" or "large date" variety,
which refers to the size and position of the date on the
Lincoln cent. 1979-S and 1981-S sets each come in either
a "Type I" or a "Type II" version, where
the S mint mark is either "filled" (also known
as the "blob" mint mark) or "clear".
1964 has a design variation where the President's portrait
on the Kennedy half-dollar has "accented hair".
The design was modified early in the production (at the
request of Jacqueline Kennedy) to mute the accenting of
the hair to a more smooth appearance. This resulted in the
"accented hair" variety being more rare and commanding
a premium over the "regular" variety.
Since 1992 the mint has struck proof sets in both silver
and base metal. Also, "Silver Premier" sets, featuring
deluxe packaging, were offered from 1992 to 1998. U.S. commemorative
and bullion platinum, gold, and silver coins are also often
issued in both uncirculated and proof types, sometimes with
different mint marks.
In most years since 1947 the U.S. mint has also produced
"mint sets", and because of the terms used there
is some confusion over the difference between these and
proof sets. These are uncirculated coins that have been
specially packaged, and (unless a scarce coin is included)
are generally neither as expensive nor as valuable as proofs.
(From 1965-67 the mint did not sell proof or uncirculated
coins, but only a hybrid product, "special mint sets."
None of these are particularly valuable.) Some U.S. mints
also sell annual "souvenir sets" from their production
runs. These are generally not of high collectable value,
although the 1982-83 sets are in demand, since no "official"
mint sets were issued during those years. Finally, individual
dealers have made unofficial "year sets". The
latter have no value beyond their individual coins. Members
of the public should be careful to understand what products
they are being offered.