How to Detect Counterfeit Coins
Counterfeit coins are nothing new to the world of coin collecting; they have been around for centuries (if not millennia). To avoid getting duped by an unscrupulous coin dealer or collector into unknowingly purchasing a counterfeit coin, there are a few basic techniques and tools that can help. In this article, I present some basic ways to evaluate your coins to determine if they are genuine or counterfeit. The methods presented below are not foolproof but can help identify the more obvious counterfeit coins.
Determine If the Coin Is Magnetic
Since silver, gold, and copper coins are not attracted to a magnet, this can be a simple test to tell if the coin has some iron content. Ferrous materials, such as iron and steel, will attach to a magnet and are not part of nearly any United States coins. A good example is a 1943 steel cent that has been copper coated to be passed off as a rare 1943 copper cent. The genuine copper version of the coin will not be attracted to the magnet; however, a copper coated steel cent will be strongly attracted to the magnet.
All United States silver and gold coins are not attracted to a magnet. Many Chinese counterfeit coins are magnetic, and it’s a dead giveaway if a silver-looking coin is attracted to a magnet. A strong Alnico magnet (see the figure) works well for counterfeit detection and can be purchased online for a few dollars. Be cautious with the magnet when you place it near a coin or object that has iron in it; the object will literally leap at the powerful Alnico magnet, and you don’t want to be in the way.
Determine the Weight of the Coin
Many counterfeit coins do not weigh the correct amount, and weighing a coin is a simple method to determine if it was struck on a planchet (or blank) made from the wrong alloy. A weight measurement and comparison to the weights is listed in A Guide Book to United States Coins (normally called the Red Book); this will give valuable information to help you determine the authenticity of the coin. If the coin does not weigh the proper amount, then it is probably counterfeit. A more complicated situation arises when a coin weighs the correct amount but still may be a counterfeit. An electronic scale capable of measuring up to 50 grams with 0.01-gram accuracy can be purchased online for less than $25.00. They are typically used in the jewelry business.
One point to consider when using weight as a discriminator is that when genuine coins circulate, very small quantities of the metal wear off. Silver and gold are soft metals and tend to wear more rapidly than a copper or nickel alloy coin. As a result, your genuine coin with lots of wear will weigh less than the specified value by a few tenths of a gram, sometimes more if the wear is excessive. If the weight of your coin is more than the specified amount, then you probably have a fake.
Measure the Diameter of the Coin
Counterfeit coins may not have the correct diameter, which is a good indication that the coin may not be genuine. A Vernier Caliper is a simple device used to measure the diameter of coins to +/- 0.1 mm. As with weight, the correct diameter is not a guarantee the coin is genuine, but it is a good data point to help you determine if the coin is real. Plastic versions of this measuring device cost less than $10.00.
Visual Examination Using a 10x Magnifying Glass
Using the 10x magnifying glass to carefully examine the coin’s surfaces and edge to look for irregularities can be very helpful in your quest to detect a counterfeit. Some things to check for: seam around the edge indicating a cast coin, small raised spots or depressions in the field of the coin, and unrealistic or flawed styling of devices and legends. Compare the coin to the picture in the Red Book or online photos of the genuine coin to look for obvious mistakes made by counterfeiters. Pay careful attention to the date and mint mark of the coin; an added or removed mint mark or altered date can make a large difference in the value of a coin.
One of the more common types of counterfeit coins is cast copies. These coins generally are manufactured not for the purpose of deception, but rather to create a copy of a rare or beautiful coin as a souvenir or promotional giveaway. Many times, the word “copy” or “replica” will appear on the reverse (back) of the coin. Cast copies are normally identified by a seam that runs around the outside edge or circumference of the coin. The seam is a result of metal that flows at the point where the two molds, obverse and reverse, come together. Most cast counterfeit coins are underweight when compared to the genuine coin. Cast coins typically have less detail than expected for a genuine coin of the same grade. Base metals, such as copper, nickel, zinc, and iron, are normally used as a substitute for the precious metal, such as gold, silver, or platinum, that would we used in genuine rare coins.
Determination If a Coin Is Made of Silver
There are different metal alloys that counterfeiters use that appear to be silver. A “Ring Test” is a simple test that can be performed to determine if a coin is silver. The potential counterfeit coin is balanced on the tip of a finger then struck lightly with a known silver coin on the edge. If the coin is silver it will “ring” for several seconds with a sweet, high-pitched sound. The higher the silver content, the longer the ring will last. A base metal coin will sound like a “thud” or a “clunk” when struck with the other coin. Be careful with this test to not drop the coin being tested when you strike it with the silver coin. I recommend practicing with known genuine coins before you evaluate potential counterfeit coins. The more you practice the test with genuine coins, the more easily you will be able to determine the difference between the sound of silver and non-silver coins.
There are other methods to identify counterfeit coins, such as chemical acid testing, an electronic tester, specific gravity testing, laboratory material properties analysis, and die variety studies. These are more advanced topics to be covered elsewhere.
One way to turn a genuine common coin into a valuable rarity is by altering the coin in a specific way. One of the most common alterations is the addition of a mint mark to a coin that did not originally have a mint mark. For example, by adding an “S” mint mark to a genuine 1909 VDB Lincoln cent (a $10 coin), the forger makes the valuable ($500 plus) 1909-S VDB cent. The mint mark is removed from a common “S” mint coin and epoxied or soldered onto the 1909 VDB coin—and voila!—an instant rarity is created. Another example of where adding a mint mark greatly increases the value of a coin is the 1916 Mercury dime. By adding a “D” mint mark to the reverse of a 1916 dime minted at Philadelphia, which has no mint mark, the value of the coin goes from a few dollars to a few hundred or more.
One other type of alteration is changing the date of the coin. For example, a counterfeiter will start with a common 1944-D Lincoln cent, worth a few cents, and alter the first “4” in the date to make it look like a “1.” This turns a 1944-D into a rare 1914-D cent worth a hundred dollars or more. This alteration can be spotted by noting the improper spacing between the digits in the date. Other such alterations are made by changing a 1941 Walking Liberty half dollar into a 1921, or manipulating the date of a common Indian Head cent to the rare 1877.
The way to detect if a coin has been altered is by knowing the characteristics of a genuine coin. Since most collectors don’t have a safe full of genuine rare coins for comparison, the next best thing is to look at pictures of genuine coins and their specific die characteristics. The books and the websites listed in the Reference section of this article contain many details you will need to use to evaluate a potentially altered coin.
Professionally Graded and Authenticated Coins
The methods presented in the guide will help you identify most of the more obvious counterfeit coins. If you are spending several hundreds or thousands of dollars for a coin, it is recommended that you purchase the coin from a very reputable coin dealer with a return policy or purchase a coin that has been professionally graded and encapsulated by services such as PCGS, ANACS, NGC, ICG, or NCS. Also, professionally graded coins are in inert and sealed holders that are excellent for long term storage and are much easier to sell.
Know Your Coin Dealer
Like nearly every other area of commerce, coin collecting has moved to the internet. Though this change has offered the collector a much larger array of coins to collect, it has also widened the gap between the coin collector and the coin dealer. If you buy your coins from a local person, for example, at a coin club meeting, a coin show, or at a coin shop, try to find out if the dealer is reputable. Most coin dealers are honest, but there are bad actors that you should avoid—ask around for references. The same advice applies when you purchase coins from a dealer on the internet.
For example, on eBay, check to see if the dealer has a lot of positive feedback or if they are a novice. If a dealer is a member of a professional organization like the American Numismatic Association (ANA) or the Professional Numismatists Guild (PNG), that helps build their credibility. When spending your hard-earned money on rare coins, the old saying caveat emptor applies, or “Let the buyer beware.” Just be a little cautious; do your homework on the rare coin you are interested in and the dealer selling the coin.
Fivaz, Bill. United States Gold Counterfeit Detection Guide. Whitman Publishing. 2005.
Lonesome John. Detecting Counterfeit Coins Book 1, Heigh Ho Printing Company. 1985.
Counterfeit Detection: A Reprint from The Numismatist, American Numismatic Association. 1988.
Counterfeit Detection: A Reprint from The Numismatist Volume II, American Numismatic Association. 1988.
Travers, Scott A. (editor). Official Guide to Coin Grading and Counterfeit Detection. The House of Collectables. 1997.
Yeoman, R.S. and Jeff Garret (editor). A Guide Book of United States Coins 2020. Whitman Publishing. 2019.
“Counterfeit Coin Detection – The Top 10 Most Common Counterfeit US Coins” https://coinweek.com/education/coin-grading/ngc/couinterfeit-coin-detection-counterfeit-detection-the-top-10-most-common-counterfeit-us-coins/
“The Fundamentals Of Counterfeit Detection - Part 1” https://www.pcgs.com/news/the-fundamentals-of-counterfeit-detection--part-1
“Counterfeit Detection” https://www.ngccoin.com/resources/counterfeit-detection/