“The only bad coin is one I don’t have” (Translator, 2008). Actually, that is not really true. There are good and bad coins. The properties that constitute “goodness” differ depending on whether a coin is intended for circulation or for commemorative or bullion use. However, some of these characteristics are common to all types. (I have not covered commemorative coins in this series. They are legal tender coins struck usually for only one year, to recognize a specific event. I will add a picture of one in a bit).

The characteristics common to all good coins include a suitable alloy, an good design, and respectability. The latter might not seem important, but it is and I will give a couple of examples. In addition, sometimes the nature of these characteristics change with time.

Alloy is important for a couple of reasons. Until circulating coins became tokens in the United States in 1965, precious metal content was important. That is why silver and gold coins had reeded edges (for the most part). A reeded edge is the series of ridges on the edge of a coin, put there to prevent shaving tiny bits of gold or silver from the coin. It actually does not prevent it, but no one would accept coins with the reeding shaved, thus making the practice unprofitable for those who would try it. By the way, reeding was left on our dimes, quarters, and halves after the silver was eliminated just for tradition.

For circulating coins, the alloy has to be hard enough to resist wear for many years. The average life of a circulating coin is on the order of decades, so this is important. All US gold and silver coins for circulation have been alloyed with copper to harden the metal. Both gold and silver, in pure form, are extremely soft, wearing rapidly and bending easily. Pure gold and silver are completely unsuited for circulating coins. Most US coins are good in this respect, with two recent exceptions. One was the 1943 cent, which was zinc plated steel. The zinc coating was relatively soft and wore away rapidly. The other example is again the cent after 1982, being zinc plated with pure copper. The pure copper plating is thin, and pure copper is soft, so the coating tends to wear.

Hardness is not a factor for bullion coins, since they are not designed to be handled. The Mint produces two different pure coins, the gold Buffalo and the platinum Eagle series. The important factor for them is that the metal content is accurate and consistent.

Another important property is resistance to corrosion. This is more important for circulating coins, since they are often subjected to harsh conditions than bullion coins, but it is still somewhat important even for those. Almost all US circulating coins are good in this respect, with only a couple of exceptions. Again, the 1943 cent was bad, because after the soft zinc coating wore, the coin tended to rust. Even worse is the 1982 and up cent, because once the copper plating wears, the coin corrodes if it gets wet. Try this: Take a pre-1982 cent and a post 1982 one (in 1982 both kinds were made, so your results may be confusing if you use 1982 ones), nick the edges of each with a knife or file, and drop in a container of water and add a little salt. Come back in a couple of weeks and see which is better.

The bimetallic dimes and quarters are OK, but under harsh conditions they are more apt to corrode than the silver ones, but much more slowly than the zinc cents. I have several that have corroded to the point of being hard to recognize.

Here are pictures of corrosion damage to a bimetallic dime (left) and a copper plated zinc cent (right):

Design includes several factors. Obviously, an attractive design is desirable for a popular coin. More important are a couple of technical issues. Round, or approximately round, coins are better than shapes with sharp corners because sharp spots wear more quickly than round ones. Another design factor is the interaction between the designs on the obverse and the reverse. Some combinations are worse than others. The Flying Eagle Cent, the first small cent, suffered from this defect and was discontinued after only three years. The heavy design on the reverse interfered with the head and tail of the eagle on the obverse because of work hardening the allow. For the most part this is not too much of a problem with US coins.

Here is a picture of the Flying Eagle small cent. I think that it is a relatively attractive coin:

A much more common and severe design consideration, for circulating coins, is high spots that wear the fastest. Obviously, it is not possible to design an image with some relief, but some elements are more important than others. For example, if the date or denomination is the highest part of the surface, it will wear off first. The Indian Head five cent piece, although an attractive and popular coin, was one of the worst. It was so bad, in fact, that the reverse was redesigned the first year of production because “FIVE CENTS” on the reverse was the highest spot on the coin and wore badly. The dies were reworked to lower the relief. The date on the obverse also wears badly, but not as bad as the denomination. There are lots of Indian Head five cent pieces laying around, and many of them have the date worn completely away, making them worthless as collectibles. This consideration is not as important for commemorative and bullion coins, since they are not intended for circulation.

Here are pictures to illustrate what the Mint did to reduce the wear on the reverse. The first one is the one that gave trouble:

There are a couple of techniques that the Mint uses to reduce wear on critical areas. The first is in the design of the coin itself, protecting critical features by assuring that they are not high spots, like the example just given. The second is the process of upsetting, where a raised rim is applied to the coin. (This is done just before the image is struck). As far as I know, every US coin has an upset rim, with the notable exception of the $2.50 and $5.00 Indian Head gold pieces, and there were unique in that the image lettering on them were incuse, that is, struck as a depressed regions rather than raised regions. These are unique in US coinage history. Here are pictures of blank planchets (coins before striking) before and after the upsetting process:

Here are pictures of the incuse Indian Head Half Eagle:

Sometimes what is NOT on the coin becomes a design defect. The initial reverse of the Liberty Head five cent piece had only a “V” on the reverse to denote denomination. This became an issue when a deaf mute in Ney York took to gold plating them and passing them off as five dollar gold pieces. (He was acquitted of any crime by the way, because his attorney convinced the jury that, since he never tried to buy anything with them that cost more than five cents and could not hear or speak to answer questions, it was the mistake of the merchant to give him the $4.95 change). The Mint quickly modified the dies to add the word “CENTS” to the bottom of the reverse, in 1883, the first year of issue.

Here are pictures of the reverse before and after the modification:

Eye appeal is important, but not absolutely critical. However there have been some really horrible looking modern coins. The Eisenhower and the Susan B. Anthony dollars come to mind. On the other hand, the Walking Liberty half dollars and double eagles are just beautiful. Here are representative pictures of each, in order of mention:

I wish that we would get back to designs like the last two, at least now and then. Those would be exciting coins for me to examine.

Recognizablility is important for all coins, and critically so for circulating coins. That is one advantage of keeping the reeding on dimes and quarters, because the visually impaired can distinguish different denominations by tactile sensation. One of the big disadvantages of the Susan B. Anthony dollar was in size, color, and reeding it looked and felt like a quarter. The Mint has tried to make a dollar coin more acceptable to the public by changing the color and eliminating the reeding, but it is a historical fact that Americans just do not like dollar coins. Silver dollars were never really very popular, except now that they are collectors items. Unless the Treasury eliminates the dollar bill, a dollar coin will not fly in my opinion. Now, there is another reason for this, too: The Federal Reserve pays the Treasury only the cost of producing paper currency (about four cents per, regardless of denomination), but has to pay full face value for coins. In FY 2007 (the latest one for which I could find figures), 4,147,200,000 $1 bills were printed, so there is some economic incentive for the Fed not to push too hard.

Those are some of the factors that differentiate “good” coins from “bad” ones. For previous installments of this series, you can use these links:

Pique the Geek: The US Cent

A Primer on United States Coins, Part 1.5

A Primer on United States Coins, Part 2

A Primer on United States Coins, with Silver Content Value as of Today, Part 3

The US Mint Ran out of Gold Today (part 4 of a series on coins)

A Primer on US Coins, Part 4: Modern Coins

A Primer on US Coins #5: Bullion Coins – Final Update

I think that next time I will discuss the actual methods used to produce coins, unless someone has a better idea. Comments, questions, and illumination are always welcome.

Warmest regards,

Doc