Understanding Counterfeit Detection

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ya but we could also bring altered and dipped coins into this discussion and added mint marks

 

And I still repeated the same mistake to someone! Doh!

I keep thinking the transfer dies the coin is sacrificed...That's only on impact dies.

question: Why is there metal flow on a depression? Is it because the metal had to "flow" through the planchet to create the design of the coin? And when the coin was complete, it left flow lines in the depression as proof it resulted from a transfer die, not an enviormental hazard like bagmarks.

It makes sense for there to be no metal flow on bagmarks. There shouldn't be...its a hit on the coin. I think when a coin is made, and the depression is repeated again onto the new counterefit coin, (Maybe, because all the details from the geniune coin are produced (sometimes) faithfully in the transfer die and therefore the coin, that is why you can have 2 fake coins produced from the same set of dies, and prove they are fake?) Correct?

thanks
PS: I still need to take that summer semininar at ANA in CO Springs, CO. I just don't have the money. Going to school this summer.

 

Great thread. Thank you.

 

Pretty much.

Suppose a counterfeiter selects as his host coin a Morgan Dollar with a bag mark in the field. The bag mark (naturally) is a mark that is incuse into the coin. When he makes his transfer die it picks up the bag mark. This mark will be raised on the die. When the die strikes a coin the struck counterfeit coin will have a depression which corresponds to the bag mark on the host coin. The depression will appear on every coin struck by that die. (That is why it is called a "repeating depression".) The depression will have luster because metal flowed across the die when it was struck. (A bag mark or other mark on a genuine coin will not have luster; instead it will show fresh metal when the surface of the coin was damaged.)

 

Here is good source for counterfeit detection...the site is run by CT's stopmotion.

http://www.numismaticenquirer.com/The_Numismatic_Enquirer/Home.html

 

Thanks for an outstanding post, Gold. I'm printing it to go in my library.

 

Thanks, now I know how to make fake gold coins :devil:

 

This is a great thread, thanks everyone for the great info

 

I am not sure how static the orientation of the obverse die remains in relation to the reverse throughout a die pairing's coin production. But I am thinking it would remain fairly constant within die states and am of the opinion would be one of the more difficult characteristics for a counterfeiter to duplicate.

 

That is a very interesting thought, can you please elaborate further?

I am always looking for more strategies to avoid buying fake coins.

 

In the original thread the idea of added mint marks is brought up. Then just a couple of days ago the other post on this topic ('Collections in Collision') tells about Mark Hofman electroplating on new mint marks. Doubt that the OP is monitoring this, but just in case, did the ANA course touch on that specific process and if so, how it might be defected? Or better yet, does anyone know if more recent classes do?

 

I don't know if you could call it a strategy to avoid buying fake coins or not.

My thoughts are when the obverse and reverse dies are installed into the coin press it sets the design orientation (obverse to reverse for the die pairing) through coinage production. A counterfeiter using a pair of counterfeit dies would also be required to install these dies to strike coins with the designs at the proper orientation.

A coin with an added mint mark (even one with the mint mark electroplated precisely to its orientation relative to the obverse design) would still retain the obverse-reverse orientation characteristic of the actual die pair that stuck the coin. Which may or may not be at the same orientation as the coin being counterfeited.

I don't know how static the obverse to reverse orientation remains for a die paring throughout coin production or through different die states.

 

I own 8 recent Chinese struck counterfeits in TPG holders; 3 in ANACS slabs, 3 in NGC slabs, and 2 in PCGS ones.

My latest from NGC came back yesterday in the imaged AU Details slab.