Deceptive Counterfeit: The Electrotype
Posted on 5/1/2007
Skip Fazzari, NCS Authenticator and Senior Conservator
One of the most difficult types of counterfeit coins to detect with the naked eye is the electrotype. Since some of these fakes can look quite good even under low magnification, it is important to be diligent. Once you have been fooled by one of these coins, in addition to a close microscopic examination, you may want to start checking the weight and specific gravity of your important coins.
An electrotype is a copy of a coin made using a process similar to electroplating. Usually, the counterfeiter makes a copy of the genuine coin that he can work with so as not to ruin the original. There are several ways to do this. While modern fakers probably use spark erosion techniques to make their models, most electrotypes we see at the grading services were produced many years ago when a simple wax impression of a genuine coin was sufficient as a starting point. The wax model is coated with a metallic powder such as graphite or copper and then it is electroplated. This process allows a thin layer of metal to be built up on the surface of the model. When the coating becomes thick enough, it’s separated from the wax form leaving a hollow shell bearing the details of one side of the original coin. A second shell is made of the coin’s other side in the same way. Finally the two halves are joined together and the hollow center is filled with metal to give the electrotype the "feel" of a solid coin.
Most of the electrotypes I have encountered over the years have been copper coins, chiefly Large cents, Half cents, and Colonials. In some instances, the base metal interior of an electrotype can be seen as its outer shell becomes worn. This is one instance that detecting an electrotype fake can be done with the naked eye but your findings should be confirmed by other tests because toning, especially on silver coins, can mimic this effect. Usually, collectors and dealers who have access to a balance may confirm that a coin is an electrotype by taking its weight and specific gravity, which are often out of tolerance to that of a genuine coin. But here again, there are rare exceptions to this, so be careful and have important coins checked by NGC.
There are several other diagnostics to look for if you suspect that a coin may be an electrotype. Perhaps the first thing to look for is evidence of a seam around the edge of the coin where the two halves were joined together. This will usually appear as a very thin, dark line running through the center of the edge. The micrograph shows such a seam. In some cases, the faker will try to eradicate this seam or at least make it less noticeable by filing or burnishing its edge. When a model is produced from the original coin, a wax impression in the example above, some of the sharp detail of the coin is lost during the transfer process. This may give the relief of an electrotype, especially its legend and date, a rounded, bloated look when compared to that of a genuine coin. Additionally, any defects that were created in the mold during the transfer process to make the electrotype and any contact marks or scratches on the original coin used as a model may appear on the fake if not "touched-up" by the faker.
This article previously featured in Numismatic News.