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Understanding Counterfeit Detection

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I posted this on coin talk and alot of people seemed to like it, so I'll post it here too


This will be a thread periodically updated as I get more material to put in this thread, it is a work in progress.

Overview of counterfeit detection

Counterfeit coins are becoming more of a problem as time passes. It is all too apparant, and grading company slabs are even being targeted. Fakes can range from crude (cast copy), to excellent (transfer die struck). Many gold coins coming from the middle east are exceptional, and it is a rule to remember that some of the best counterfeits, if it looks too good to be true, it probably is.


In the summer of 2002, first brought to the attention in the magazine Coin World, a very strange error coin came. The existence of a 'mule' consisting of the obverse of a 1959-D cent and the reverse (wheat ears) of a cent from 1958 (or earlier). To Bob Campbell, a famous autheticator, the coin just didn't "look right", he said "Something about the coin just didn't seem right", later he said, "The fabric was there and everything pretty much looked correct, but it just felt wrong -- not a physical kind of 'feel' but more of a gut like feeling." Indeed, the coin looked too good. How could such a spectator error go unnoticed ? That's because the coin was a forgery, different from a counterfeit. Generally counterfeit coins are contempoary, they are mean't to be used in circulation. Where as a forgery, is made to fool numismatic experts and dealers.


More about the coin, it was actually made by infamous Mark Hofmann. He once said, "If I can produce something so correctly, so perfect that the experts declare it to be geniune, then for all practical purposes it is geniune. There is no fraud involved when I sell it."


In his book Numismatic Forgery, Charles M. Larson, who was the sergent at night when he worked at the prison which Mark Hofmann was sentenced to, talked and interviewed Hofmann several times. Hoffman told Charles that he used an ingenious method of creating dies using an electroplating process.


You can read more about Numismatic Forgery in Charles Book, Numismatic Forgery

A few rules of thumb:


Generally there are different types of creating counterfeit coins and how to spot them. Many times counterfeiters would actually melt down a very worn (but authentic) $20 double eagle to make several $1 gold coins, which have a high numismatic value relative to their intrinsic, or gold content. This way the gold used has the same fineness as geniune mint gold, as well as the proper alloy. (Because the worn $20 is a geniune coin, it can be purchased for less than fifty dollars over spot of the gold it contains.)


As a general rule, it is said that coins that are EF or lower, chances are it is geniune.


Overview of different counterfeit types:

Cast counterfeits:

Generally, cast counterfeits are the most poorly made. Often you will see blobs of metal through the letters or devices of the coin. Often times, as well they can be identified by a seam that runs about the outside edge of the coin. Casting can be made from plastic molds, using centrifugal force. Cast counterfeits, unlike transfer die high quality counterfeits, are often underweight and may use a different material (such as tin), instead of silver if the coin is a silver coin.




These are generally used by museums.They are made by impressing a geniune coin nito a soft substance and electroplating the negative impression, creating a positive shell. Generally the edge can give this away, as with cast counterfeits many electrotypes have a seam around the edge. Generally when "rung" electrotypes will not sound right, because of the process made.


Transfer dies:

These are the most common used and also the most deceptive.

The counterfeiters actually create a working die this time, but since they are using the same die all imperfections struck from those dies will go onto the coins. Sometimes there will be a blemish on the die, and the counterfeiter tries to remove it.


A typical struck counterfeit:




This leaves short, stubby lines on the finished coin called toolmarks. Alot of Indian head gold coins have toolmarks in the recess of the neck. Also since the counterfeiter is using the same die, there are things known as repeating depressions. The reason they are repeating is because any coin struck with that die will have the same imperfection. A geniune coin must be sacrificed as a host to make the transfer dies. Because the geniune coin used will have contact marks, the metal flows into the planchet creating what is known as depressions on the counterfeit coin.


High quality (probably middle eastern) struck counterfeits, all returned body bagged as counterfeit by PCGS.



These are small, often circular crators in the coin which often blend with the surrounding field, but because they were struck, they have luster inside them. Often a contact mark is shiny and does not blend in with the fields of the coin because the metal is disrupted.


It is said that the most common counterfeited coins are the ones collectors buy the most, because of demand. This is what Charles said in his book, Numismatic Forgery. For some reason, there are few counterfeit coins before 1840.


A counterfeit gold coin (probably another base metal) in a counterfeit PCGS slab. This was found on ebay from a seller oversea's. Counterfeiting slabs are becoming more of a problem and NGC has taken actions with this in their slabs



Spark Erosion Counterfeits:

These are generally easy to detect because how they are made.

In this process, A geniune coin is put in an electrolyic bath where the coin faces the counterfeiter's die steel. An electrical current spark is charged t hrough the coin so that the spark goes across the shortest gap between the coin and die, creating the coin's design onto the steel die


Often times these coins are heavily pitted because of this process..so the counterfeiter's polish the dies to make up for this. These can be detected by their lumpy devices, and are often found on small type coins like cents and dimes.


Some rules of thumb:

Because of the transfer die process, many gold coins use this. Also, because a geniune host coin is used and a crude die is made, called an impact die, there is generally loss of detail on the counterfeit coin.


A good thing to do is look at many geniune coins in a paticular series. Once you know what a geniune coin looks like, in general, counterfeits become much easier. Generally geniune coins have sharp, crisp letters and devices, numbers as well. Weak fatty letters and devices are a dead giveaway the coin is counterfeit. Please remember that generally you need many different attirbutes to determine a coin throughoutly counterfeit, for example if you just find a depression or two on the coin, this is not enough to deem it counterfeit. Depressions can also be mint made, but often they do not have the luster that a counterfeit coin has.


Another thing to look for on counterfeit gold coins are spikes from the denticals or devices, such as stars of the coin. I'm actually not sure what spikes are caused from, but I know that spikes along from the denticals ont he coin are not enough to deem it counterfeit; as discussed earlier because sometimes geniune coins have them too. According to expert numismatic authentication expert Randy Campbell, about 3% of geniune coins have them.



Color is another thing to look for on counterfeit coins. Generally sometimes, the color is just "off" and it doesn't look right. This can only come with years of looking at geniune coins and knowing your series well. For example, branch mint coins struck in Charlotte, North Carolina usually have a red hue, where coins minted in Dahlonega, Georgia, or new orleands, and also Louisiana often have a greener cooler.



On cast counterfeits, often the coin is not the correct weight weight, so you may need to weigh them. Many transfer die struck gold coins are the proper weight and fineness (because of , in some cases, a melted double eagle makes several gold dollars)


Many counterfeiters do not take the time, unlike the mint, to polish their dies. Therefore lots of die polish relevent in protected area's of the coin, are a good sign or a possible sign it is geniune


Often times what counterfeiters will do is buy a blank planchet, which the mint has made (on accident) (such as a silver dime planchet for a 16-D mercury) and use that to create the counterfeit coin.


I hope this information helps learning more about counterfeits.

The key is to look at as many coins certified by the Top TPG's, that are geniune, so you know anything that doesn't look geniune is suspect.


Credit goes to Numismatic Forgery, United States Gold counterfeit detection guide by Bill fivaz, and the guide to grading and counterfeit detection by PCGS.


Counterfeit dies made from chinese counterfeiters:




Excerpt from Bill Fivaz book, on counterfeit gold. Notice the linear depressions (which is from when something gets stuck on the die and is struck, leaving a depression), and the luster within the other depressions.

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Nice post there Kevin. It's good to see that you put your paranoia to rest with gaining more knowledge of the subject. I give you great credit for that! (thumbs u

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Nice post there Kevin. It's good to see that you put your paranoia to rest with gaining more knowledge of the subject. I give you great credit for that! (thumbs u


Thanks, I think I have my paranoia under control but it never goes away.


I have said earlier that I want to become a counterfeit gold expert, that is my goal. I'm glad you like the thread.


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Nice post, Kevin. Good write-up.


Thanks Oldtrader, I really tried on this thread. I originally posted it on coin talk and on coin talk I added my notes from the class I took, but I don't think I need to add that here.

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Kevin, congratulations, with your goal in sight you have most certainly turned a corner. Interesting article and well researched. I am impressed. Keep it up and you will enjoy your hobby much more.


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