- Proof coinage
Proof coinage means special early samples of a
coinissue, historically made for checking the dies and for archival purposes, but nowadays often struck in greater numbers specially for coin collectors ( numismatists). Many countries now issue them.
Preparation of a proof striking usually involved
polishingof the dies. They can usually be distinguished from normal circulation coins by their sharper rims and design, as well as much smoother "fields" - the blank areas not part of the coin's design.
The dies for making modern proof coins are often treated with chemicals to make certain parts of the design take on a
frosted appearance, with the polished fields taking on a mirror finish. Several other methods have been used in the past to achieve this effect, including sand blasting the dies, and matte proofs. Proof coins of the early 1800s even appear to be scratched, but it was part of the production process.
Most proof coins are double struck. This does not normally result in doubling that is readily observable, but does result in the devices being struck fully.
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. Mintbegan producing proof sets. Sets struck from 1936–42 and, when resumed, from 1950–72 include the cent, nickel, dime, quarter, and half dollar (From 1965 to 1967, the production of proof sets was suspended and Special Mint Sets were made in their place. They were made because of a coin shortage. They were made at the San Francisco Assay Office but bore no "S" mintmark.) From 1973 through 1981 the dollar was also included, and also from 2000 on. Regular proof sets from 1982 to 1998 contain the cent through the half dollar.Fact|date=February 2008
Other sets, called "Prestige Proof" sets, also contain
commemorative coins. These sets were sold from 1983 to 1997 at an additional premium. As Legacy Proof sets, the practice was resumed in 2005. 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, proof sets include the four Presidential dollars for that year, although the proof sets can also be purchased without the Presidential dollar coins.Fact|date=February 2008
Since 1992 the mint has struck proof sets in both
silverand base metal. U.S. commemorative and bullionplatinum, 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. Some U.S. mints also sell annual "souvenir sets" from their production runs and 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.
During the early part of the 20th Century, a technique was invented in France which produced Proof coins with a Matte, or semi-rough surface. This technique involved the sandblasting of the coining dies to create this special surface. Thought to highlight the design, it became popular in Europe. The Philadelphia Mint used this process in a limited way for several coin series. Though not popular with collectors at the time, these pieces today are eagerly sought by numismatists. Most common of these coins are the Matte Proof Lincoln Cents, struck from 1909 to 1916. Through these years, a total of approx. 15,000 matte proof lincolns were struck. They are today among the rarest and most desirable Lincoln Cents. Identified by a series of well known diagnostic features, many are encapsulated by third party graders and authenticated as Matte Proofs. When new, they were sold wrapped in a 'tarnish proof tissue' which over time proved to be anything but. Many of these coins today show vivid colors, ranging from mint orange/red to greens, blues, lavenders, turquoise and deep reds. Raw (unencapsulated) matte proof lincolns are easily identified by their wide, square outer rims, unlike the gentle rounded rims of business strikes. This is a product of the extreme high pressure hydraulic press used in the Philadelphia Mint Medal Room for their production. Matte Proofs also are found in the gold coins of the era, 1913 to 1916 Buffalo Nickels and in a few Peace Silver Dollars. These are extremely rare.
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