The front or head of a coin is called the Obverse and the back or tail of a coin is called the Reverse.
The principal design object represented on a coin is the called the Type, such as the Liberty $20 gold is a different type than the St. Gaudens $20 gold.
The space between central design and the edge of the coin is called the Field. The term mirror fields describe a coin where the fields are highly reflective.
The mint mark is a small letter or letters that denote place of mintage. “S” for San Francisco, “D” for Denver Colorado in the 20th Century and “D” for Dahlonega Georgia in the 19th century; “O” for New Orleans, “C” for Charlotte, North Carolina, “CC” for Carson City, Nevada and if no mint mark, Philadelphia. Beginning in 1980 the “P” mint mark, for Philadelphia, appears on nickels, dimes, quarters and half dollars. 1983 saw the first appearance of the “W” mint mark, from the West Point Mint Facility. Today the American Eagle silver, gold and platinum bullion coins, along with all gold commemorative and a few silver commemorative coins are made at the West Point facility. All commemoratives from this mint are struck with the “W” mint mark.
The lower portion of the area of a coin beneath the design and separated from the rest of the field by a horizontal line is called the exergue. A good example of this is the Buffalo 5c. The buffalo actually stands on the line and the words “FIVE CENTS” and the mint mark are in exergue.
The inscription on a coin is called the Legend. When coins have inscriptions around the edge, they are called Lettered Edge.
Small objects represented in the field or in exergue are called Symbols. Mint marks, representing place of mintage, such as “S” for San Francisco, are good examples of symbols.
Coins where portions of the design are sunk below the level of the surface are said to be incuse. The United States Indian Head $5 and $2.5 gold coins are examples of incuse coins.
When a die, made in one year, is used in a later year by engraving over the old date with the new date that is called an over-date. Over-dates can also be created by error by engraving the date numerals in the wrong position on the coin, polishing the numerals off the coin and re-engraving the numerals again.. The shadow of the old numerals are still visible in the field surrounding the new numerals.
Doubled die coins are coins with parts of the design type or legend appearing as a doubled image. These coins come from a improperly made die. The doubling comes directly from the die and is not a result of a minting error. The 1955 Doubled die cent or the 1939 Jefferson nickel with doubled Monticello are examples.
