The Counterfeit Coin Detection Kit

How to Detect Counterfeit Coins Using 5 Simple Tools

Digital Caliper
Digital Caliper. (c) James Bucki

Anybody can detect counterfeit U.S. coins using five simple, inexpensive tools. In this article, I explain what these tools are and how to use them to protect yourself against fake coins and counterfeits. 

Although these tools and methods described below can detect counterfeit coins, but also you must realize that you cannot identify all fake coins by these methods. In other words, some counterfeit coins are so well made that they will avoid detection by the means listed here. If you are buying a rare coin that involves a significant amount of money, your best bet is to buy the coin in a certified holder from a third-party grading service. This way, you can be assured that the coin you purchased is genuine and accurately graded.

  • 01 of 05

    A Simple Magnet

    TEK IMAGE/Getty Images

    You can use a simple magnet to rule out many Chinese-made counterfeit coins because about 70% of all fake coins from China are produced with iron-based planchets (coin blanks). Since there has only ever been one single circulating U.S. coin that should be attracted to a magnet (the 1943 steel penny), virtually any U.S. coin that sticks to a magnet is counterfeit.

    How to use: You will need a strong magnet to detect small amounts of iron. Hold the magnet near the coin and see if they attract, even a little bit. If the magnet sticks to a U.S. coin, the coin is virtually guaranteed to be a counterfeit. Canada and other foreign countries have been using steel in their coin blanks for decades, so this test has no meaning for many Canadian coins.)

  • 02 of 05

    A Gram Scale Accurate to at Least One Tenth Gram

    Precision Digital Scale
    James Bucki

    Many Chinese Counterfeiters use scrap metal to make their coin blanks. As a result, the coins are usually underweight. The coins can also be light for other reasons, such as shrinkage from using cast dies or cast blanks. The United States Mint adheres to very narrow tolerances for error in weight and diameter, so any U.S. coin that is off by more than 1% is highly suspect.

    How to use: Make sure your scale can weigh down to a tenth of a gram (0.1 g.). A scale that can weigh in increments of one-hundredths of a gram (0.01 g.) is better. Do not use diet scales that weigh whole grams because they are not accurate enough. Place the coin on the scale and then compare the weight to the known proper weight standard for that coin. If it is off by more than 1%, the coin is a suspected counterfeit. Additionally, a well-worn coin may still be genuine but be severely underweight due to the abnormal amount of metal that has worn off the coin.

  • 03 of 05

    A Caliper Accurate to the Hundredth of an Inch

    Digital Caliper
    James Bucki

    A caliper is a device that is used for measuring the diameter of a coin. The United States Mint is extremely precise in making coins of the proper diameter, so any coin that is too small, even by a little bit, is highly suspect. Counterfeit coins are frequently underweight and undersized.

    How to use: Slide the caliper jaws to the closed position and calibrate it to zero (usually by pressing a "set" or "zero" button.) Then slowly slide the jaws open until they are touching the edges of the coin across from each other. Make sure the coin is snug between the jaws (but not too tight) and read the result. Compare your measurement to known U.S. Mint standards for that coin. If the coin is too small, it is a suspected fake.

  • 04 of 05

    A High-Powered Magnifying Glass and Light

    Desklamp, Loupe and Magnifying Glass
    James Bucki

    A magnifier that has a minimum power rating of 8x (8 times magnification, or "8 power") will allow you to see details on the surface of the coin that are invisible to the naked eye. Ideally, you should use a 10x or 12x triplet loupe, which has much greater clarity (but is also more expensive.)

    Additionally, a quality light source must be used in order to illuminate the coin being studied properly. A standard desk lamp with a hood that is painted white on the inside will work well. Make sure to use an incandescent lightbulb of approximately 75 W. If an incandescent bulb is not available, then a standard LED pure white lightbulb can be used.

    How to use: Hold the coin in one hand, and the magnifier in the other. Move the coin around to inspect its surface, looking for signs of bubbles or pimples on the surface, or seams or file marks on the edge. Also, look for characteristics typical for that type of coin by comparing it to a known genuine specimen. "Soapy" looking or bumpy surfaces can be a sign of a counterfeit. Pay particular attention to the surface of the devices on the coin because these parts of the coin are usually not polished during the counterfeiting production.

    Continue to 5 of 5 below.
  • 05 of 05

    A Reference of Standards for U.S. Coin Types

    books and coins
    Seamind Panadda / EyeEm

    To determine if your weight and diameter measurements are within U.S. Mint tolerances, you will need to compare them to known U.S. coin specifications. Most general-purpose coin price guides, such as the Red Book have these specifications noted. Although the allowable amount of deviation from the Mint's specifications varies for each type of coin, all of the tolerances are very, very small. Any coin that is a gram underweight or eighth-inch too small is way out of tolerance and probably a fake.

    How to use: Weigh and measure your coin, and compare your findings to known specifications. If they are off by more than 1% (either too heavy or too light), your coin is a suspected counterfeit.

    Edited by: James Bucki