Basic Guide to counterfeit coin detection

I've been wanting to write something like this for a while, as I've been stung before and I'm sure others have. I will add pictures for examples at some point.

The first stage of detection is the picture stage which you will analyse pre purchase. Much purchasing is done online these days, so this is very important.

Ensure the seller provides a clear picture; if you don't have one, don't proceed.

1. Ensure the obverse and reverses match the available ones for the stated date. For example a type 2 reverse on an earlier date coin may prove it to be fake.

2. Ensure there are no granular lumps or depressions on the coin. These are caused by abrasions or faults in the host coin, and are transferred onto the counterfeiters die. Raised lines are also common, caused by scratches on the initial coin and transferred to the counterfeit dies.

3. Ensure sharp contrast between the devices and fields. On poorly struck or cast counterfeits this will be most obvious.

4. Don't get hung up on minute details that could be caused by wear. Instead focus on the major design elements.

5. Note the type of coin. On most modern coins the rims are flat and consistent and the dentils are consistent. Check these carefully as they are often overlooked by counterfeiters. If the dentils are variable, fused together, or otherwise suspicious you should check how common this is for that specific coin.

6. Check for 'bumps' in the dentils or edging, where it curves in. This is often not checked, but an excellent way of detecting fakes. It is caused by a edge bump on the host coin, which is notoriously difficult to forge correctly.


Once you have the coin in hand, check the following.

1. The weight. Wear does not account for more than 0.2 grams or so, so if the coin is more than 0.2grams off either way, be very suspicious. That said, genuine coins are often off a tad, so allow 0.1 grams for that depending on the series.

2. Diameter. This is best checked by using a USB microscopes measuring feature.

3. The edge. Counterfeiters usually neglect the edge as they are rarely photographed, but they can tell you a lot. Reeded edges should usually be regular and consistent, and reach all the way to the rims. Check other coins of the same type to check. In the case of 8 Reales coins, the edge alone can pretty much guarantee authenticity, but that's beyond the scope of this post.

To be continued, but that's it for now!

- Ensure that the price is on line with the standard price
- View each negative comments about this seller to see if a customer says "Fake!"
- Get through Aliexpress / Alibaba etc ... websites to check if your coins is not sold at 1$ (free delivery)

I think what is also important is to know what coins have been subject to counterfeiting in the past. There are coins that are known to have counterfeits. I don't deal in high end coin collecting and that is where most of the counterfeiting is going to be found-it has to be worth the while, to counterfeit to make a profit. Most of the coins I have are not worth the time to counterfeit.

I have only come across one counterfeit in my travels. It was a gram of gold, which turned out to be gold plated silver. The coin dealer I brought it back to (he's been in the business since 1968) said there was no way he could tell it was a counterfeit, which was true. He thought it was most likely from China. They probably produced these fakes in the thousands so that there was a profit margin-so that it was worth while to counterfeit. The only reason I knew it was a fake was that I checked it out at dealer that had a machine that could detect metal content, and that is the only way to really know if it was counterfeit.

Quote: "frankb" and that is the only way to really know if it was counterfeit.

​Not true, the ice test would have told you it was not gold because it would have told you it was silver, but who would try the ice test on their gold?

Quote: "redsmithstudios"​

Quote: "frankb" and that is the only way to really know if it was counterfeit.

​​Not true, the ice test would have told you it was not gold because it would have told you it was silver, but who would try the ice test on their gold?

​
Gold conducts fairly well at 273.2k. Not as well as copper or silver, but still nicely.

The answer [for gold] is of course the specific gravity test. This will tell you that you have either gold or gold plated Tungsten (Or Plutonium/Uranium, but I'm counting those as rather unlikely metals of choice for coin counterfeiters .)

You then move on to some other stuff to determine gold if you can't scratch the coin. (Or test for conductivity if you're a special child)

I am going to cover specific gravity and DIY ultrasounding in the next episode!

Quote: "oggy"​

Quote: "redsmithstudios"​
​

Quote: "frankb" and that is the only way to really know if it was counterfeit.

​​​Not true, the ice test would have told you it was not gold because it would have told you it was silver, but who would try the ice test on their gold?

​​
​Gold conducts fairly well at 273.2k. Not as well as copper or silver, but still nicely.
​
​The answer [for gold] is of course the specific gravity test. This will tell you that you have either gold or gold plated Tungsten (Or Plutonium/Uranium, but I'm counting those as rather unlikely metals of choice for coin counterfeiters .)
​
​You then move on to some other stuff to determine gold if you can't scratch the coin. (Or test for conductivity if you're a special child)
​
​I am going to cover specific gravity and DIY ultrasounding in the next episode!

​Never heard of the ice test, or specific gravity. It would nice to own an x ray machine, but I'm sure they cost a ton of money.