For a coin to be considered a coin, it must contain three distinct features: the name of the issuing nation, a denomination, and a date. Additionally, however, coins also contain a number of other features that distinguish them anatomically. Perhaps the most basic anatomical features to mention are devices and fields. Device denotes all of the design elements on a coin including portraits, pictures, and inscriptions; both the mint date and a leader’s face on the surface of a coin are considered devices. The field, on the other hand, is the background onto which the devices are added; this can be highly polished to add greater contrast and beauty to a coin.
Devices can be further divided based on a number of variables. A device can either be impressed into a coin’s surface, called incuse, or raised up relative to the field, known as relief. Devices that consist primarily of words and letters are known as inscriptions and include the pertinent information on the coin. The inscription that details the principal inscription on a coin is called the legend, while those that include inspirational phrases are known as mottos. For instance, U.S. Mint coins contain a legend that reads “UNITED STATES OF AMERICA” and mottos bearing the phrases “E PLURIBUS UNUM,” “LIBERTY,” and “IN GOD WE TRUST.” Other important inscriptions include the mintmark, which denotes the mint at which the coin was produced; the denomination, or face-value; and the mint date, which indicates the year the coin was produced. An area below a major device that contains an inscription is known as an exergue.
Coins generally have two sides, the front or “heads” side, known as the obverse, and the reverse, often called the back or “tails” side. A coin’s obverse is usually distinguished by a portrait or depiction of an important individual, or in the case of some older U.S. coins, the image of a personified Liberty. One interesting feature of most coins is that they always remain rightside-up if flipped vertically; if flipped horizontally, however, the side you see will be upside-down.
The outer edge of a coin also has a uniquely defined anatomy consisting of the rim and the edge. The rim is the raised portion along the outside edge of a coin. Rims are often raised slightly above the highest portion of a coin’s relief so as to protect the coin’s devices from wear and to aid in stacking. The edge is the outer portion of a coin that you see when examining a coin from the side. Edges frequently have a design and may be reeded, lettered, or decorated. Reeded edges are the lined edges you see on dimes and quarters, and were originally used so that merchants could determine if people had been filing bits of precious metal off of the edges of their coins. Lettered and decorated edges usually include some kind of significant motto or motif and can also be seen as a form of security against counterfeiting as they are difficult to reproduce. One of the features of modern U.S. dimes, quarters, and half dollars is that they are cupro-nickel clad coins, but they were previously made using silver. Take a look at some quarters and dimes from the side. If you see the edge is a solid silver color that does not contain a band of copper, that coin is probably silver and can be worth much more than its clad counterparts depending on the price of silver at the time.
Size is another significant attribute of a coin. Coins of a particular type have very uniform sizes with very little variation. Weight is also important, especially for coins containing precious metals, as metallic elements such as gold and silver have specific weights that are not easily replicated. An aspect of size that is highly varied in today’s coin market is shape. Many coins come in non-standard shapes such as cylinders, lockets, rectangles, triangles, scalloped “flower” patterns, and fan shapes. Remember, as long as these non-standard shaped items contain the name of an issuing nation, a denomination, and a date, they are legal tender coins. One excellent example of a non-standard shaped coin is the Perth Mint’s 1 ounce silver map-shaped Australian dollar.
In addition to non-standard shapes, there is an increasing number of coins with non-standard design elements, such as lenticular holographic coins and colorized coins. There are also a variety of finishes such as proof, reverse proof, burnished, gilded, and antiqued that add to a coin’s visual appeal by changing its luster. For instance, proof coins usually feature a mirrored field with contrasting frosted cameo devices; reverse proof coins are the exact opposite and feature mirrored devices on a frosted field.
As security and the risk of counterfeiting becomes more pronounced, many national mints are including security features such as laser-engraved marks and individual serial numbers on their coins. For instance, the Royal Canadian Mint’s Gold Maple Leaf coin has a laser etched security mark on it that can be read and validated by a special laser scanner.