How to Detect Counterfeit Coins

a counterfeit coin being measured by a high precision digital caliper.
Measuring a coin's diameter with a high precision digital caliper. James Bucki

The art and deception of counterfeiting coins have been around since ancient artisans first minted coins in 600BC. Originally, people counterfeited coins with the intention of deceiving merchants and citizens. In modern times, counterfeiters make counterfeit coins to deceive coin collectors. Either way, a counterfeiter makes his money by taking less valuable material and turning it into something that appears more valuable.

What Are Counterfeit Coins?

A counterfeit coin is any coin that is made by an individual without the knowledge and consent of the issuing country or entity. Additionally, ordinary coins may be altered to look like more expensive coins. Although this is technically not counterfeiting, it is considered deceptive. Dishonest people are always developing new methods of counterfeiting coins. In China, it is completely legal to make "replica" coins from another country, and they are always achieving new and better counterfeiting techniques.

A basic skill set of how to detect counterfeit coins will hopefully save you money by avoiding the purchase of counterfeit coins. If you're going to be spending a substantial amount of money on a coin, it is a good idea to protect yourself by adhering to these four principles:

  1. Only buy coins that have been certified by a third-party grading service.
  2. Build a relationship with a knowledgeable coin dealer and buy your coins from that dealer.
  3. Do not buy bargain coins offered at flea markets and online.
  4. If you think a coin may be counterfeit, seek a second opinion before you buy it.

Types of Counterfeit Coins

Counterfeit coins can be grouped into three different categories: struck counterfeits, cast counterfeits, and altered coins.

Struck Counterfeits
Counterfeiters make struck counterfeit coins the same way a mint manufactures a genuine coin by a planchet being struck between two coin dies in a coining press. The counterfeiter can create the coin dies by engraving them by hand, using the spark erosion method, using a one-to-one transfer engraving lathe, using the plating method, or the impact technique.

The counterfeiter then loads the coin dies into a coining press that uses several tons of pressure to strike the counterfeit coins. This manufacturing process is the most tedious and most expensive way of creating a counterfeit coin. Therefore, only the more valuable coins are counterfeited using the struck counterfeit method.

Cast Counterfeits
An inexpensive way to produce counterfeit coins is to create a mold of the genuine coin and use it to cast a counterfeit coin. Creating the mold is fairly simple and straightforward. The host coin is used as a model to create the cast. Counterfeiters like this method because this process does not destroy the host coin. Once the molds are ready, the molten metal is poured into the mold. More experienced counterfeiters will use a centrifuge to make sure that the molten metal flows to the farthest recesses of the mold.

Altered and Doctored Coins
The cheapest and quickest way to make money by deceiving a coin collector is to take an ordinary coin and modify it to look like an expensive and rare coin. For example, a counterfeiter can purchase a 1909 Lincoln cent with the designer's initials of V. D. B. on the reverse for under twenty dollars. A skilled counterfeiter can then add an S mint mark to the obverse and make the coin appear to be worth over $700.

Split coins are another example of a counterfeit coin that has been radically altered. The counterfeiter will take two common coins, split them in half, and glue or solder the two halves together. This process will yield a coin that will give the illusion of a rare and more expensive coin. For example, a Buffalo nickel minted in 1926 at the Philadelphia mint can be purchased for under $100. Another Buffalo nickel minted in 1929 at the San Francisco mint can also be purchased for under $100. A skilled counterfeiter can split the two coins in half and use the obverse of the 1926 nickel with the reverse of the 1929 nickel from San Francisco and create a 1926-S Buffalo nickel that is worth close to $10,000.

Counterfeit Coin Diagnostics

Several scientific methods may give you a clue if a coin is counterfeit or not. The first is to have access to detailed specifications of a genuine coin. These should include size, diameter, thickness, metal composition, weight, and specific gravity. Use a high precision caliper to measure the diameter and thickness of the coin. Use a scale that is accurate to within 0.01 grams to measure the weight of the coin. Compare your results to that of the genuine coin. If they are significantly off, you may have a counterfeit coin.

Use an extremely strong magnet to see if the coin is attracted to it. If the official composition of the coin states that it does not contain any steel, the coin should not stick to the magnet. On the other hand, if an official coin specification states that it does contain steel, then a genuine coin will stick to the magnet. The United States mint only made one coin that contains steel: the 1943 Lincoln cent.

Next, look at the coin's color to make sure it matches the metal composition of a genuine coin. For example, a 1943 Lincoln cent should be made out of zinc plated steel. Therefore, it should have a gray steel metal color. However, the United States Mint accidentally made a few 1943 Lincoln pennies out of copper. Counterfeiters have taken genuine 1943 steel pennies and plated them with copper. Therefore, if a 1943 copper colored Lincoln penny sticks to a magnet, it is an altered coin that is now counterfeit.

Study examples of genuine coins or find high-resolution photographs on the Internet to learn the unique features of an authentic coin. Areas you should study include the shape of the letters, the position of numbers, details on portraits, and the overall look and feel of a genuine coin.

The United States Mint has always had high-quality standards. Therefore, when inspecting a coin under magnification, the devices should be crisp and clear and the surfaces clean and smooth. Coins that have soft, mushy letters and devices are an indication the coin might be counterfeit. If the surfaces of the devices are course and lacking in detail, this may be another indication of a counterfeit coin.

Finally, look carefully at the coin with a high-powered magnifying glass or stereo microscope. Inspect for evidence of alterations that may include the addition or removal of a mintmark that would make the coin more valuable. Inspect the edge of the coin for evidence of a seam that would indicate the coin is a cast counterfeit or an altered coin made by joining two halves of genuine coin together.

Improving Your Counterfeit Detection Skills

Some high-quality counterfeit coins have even fooled expert numismatists. It is important to understand the minting process for the individual coin that you are inspecting. For example, the very first coins made at the United States Mint were made from coin dies that were individually hand-engraved by an artist. When that die wore out or broke, the artist would create another one. Therefore, although two coins may be the same denomination and date, coins produced from different handmade coin dies will have differences.

The United States Mint purchased its first reducing lathe in 1833. The lathe was the first step in automating the production of coin dies to ensure design consistencies for the entire year of production. In other words, a coin produced at the beginning of the year with one coin die would be almost indistinguishable from a coin produced at the end of the year with a different set of dies. However, some inconsistencies still existed with this manual process.

The modern minting process now uses computers, hydraulic presses, and automated processes to ensure that every coin is virtually indistinguishable from the next. These advances have made modern coins more difficult to counterfeit.

Finally, becoming an expert in detecting counterfeit coins is a lifelong process that takes many years to hone your skills and constant research on current counterfeiting techniques. Studying genuine coins alongside known counterfeit coins is the best teacher on your road to becoming an expert counterfeit coin detector.