Circular depressions

[stinkycheese1]

When I took my authentication course in phoenix, something they mentioned that come up very often in counterfeits are depressions. These are pits in a coin in which was contact marks on the die used to counterfeit the coin. Counterfeits from the same die often have the same depressions hence 'repeating depressions.'

 

Something I noticed in examining the counterfeit gold coins was that most of these depressions were circular. There were linear depressions too but most were circular pits. Contact marks were shiny but the depressions blended in with the luster in the fields.

 

Does anyone know why most depressions (big and small) appear circular?

 

[TomB]

It seems to me that if you created a depression in the die used to strike a counterfeit that you would then end up with a raised mark on the subsequent counterfeit piece. Regardless, semi-circular or circular marks likely have as much to do with the shape of the tools used to produce and finishe the die as with anything else.

[stinkycheese1]

It seems to me that if you created a depression in the die used to strike a counterfeit that you would then end up with a raised mark on the subsequent counterfeit piece.

 

Yeah, that makes sense. Strange.

 

But on the coin the depressions were just that -- depressions pits in the coin. (unless I'm wrong?). There were raised metal/pimples too on some of the coins.

 

Perhaps someone could correct me?

[stinkycheese1]

My bad. Instead of contact marks on the die, I mean contact marks on the geniune coin that is used in a transfer die. After the coin is sacrificed in the transfer die all copies of the geniune coin from the counterfeiting process where the contact marks were on the geniune coin appear as depressions on the fake coins.

 

I think thats how it works. If not someone can correct me.

[James_OldeTowne]

I do hope someone will be able to answer. I'm looking forward to learning about this as well.

[TomB]

If you mean contact marks on the original coin then these are most likely simply bagmarks or other marks from circulation or mishandling that the host coin has acquired.

[construct]

A depression on a counterfeit coin is a copy of a hit on the (genuine) original coin from which the counterfeit die was made. Since most hits are basically circular, most depressions are basically circular as well. Some hits are elongated; so the corresponding depression would be elongated. It's as simple as that.

[Conder101]

Interesting, I would have thought that circular depressions would be the result of trapped bubbles in casting.

 

Since most hits are basically circular, most depressions are basically circular as well.

I don't really see contact marks on coins as being circular in shape. Having a curve to them maybe, but not circular.

[RWB]

There are two kinds of depression relating to counterfeit coins:

The depression in the fake caused by copying an original coin or from casting, and

The depression you feel when you learn that the seller of the fake High Relief $20 you just bought lives in an unlisted country.

 

[construct]

Interesting, I would have thought that circular depressions would be the result of trapped bubbles in casting.

 

I was refering to struck counterfeits rather than cast counterfeits.

[stinkycheese1]

Interesting, I would have thought that circular depressions would be the result of trapped bubbles in casting.

 

I was refering to struck counterfeits rather than cast counterfeits.

 

Yes, exactly. That's what I meant. I was only looking at struck counterfeits.

 

[Conder101]

My point as well. I can't understand the source of circular depressions on a struck counterfeit. To me the would be something you would see on a cast one. I could understand circular depressions in the face of a cast die used to make struck counterfeits, but those would result in raised circular lumps on the coin not depressions.

 

I know that a die made from a genuine coin can repeat the contact marks from the genuine to the counterfeit, but I don't see why they would be circular since I haven't seen many circular contact marks.

[stinkycheese1]

My point as well. I can't understand the source of circular depressions on a struck counterfeit. To me the would be something you would see on a cast one. I could understand circular depressions in the face of a cast die used to make struck counterfeits, but those would result in raised circular lumps on the coin not depressions.

 

I know that a die made from a genuine coin can repeat the contact marks from the genuine to the counterfeit, but I don't see why they would be circular since I haven't seen many circular contact marks.

 

Maybe circular is the wrong word.

 

Thinking I may have been wrong, I just looked at the bill fivaz book, flipped it open to a random page, and found a liberty gold coin with a circular depression. They just look like circle pits.

 

If you have the bill fivaz book, its page 149 on the reverse.

It says depression and tool marks in the field; depressions below eagles right claw and on center branch.

It's a 1906 liberty head $10 example 2

[stinkycheese1]

Interesting. I just reviewed my notes for the class on authentication I took. Apparently all linear depressions are caused by lint that was between the dies when struck. Mark Feld has a coin up for sale that has a mint made linear depression. If these are both similiar, how is it possible to deferrentiate the two?

 

I guess this is why my instructor said to deem a coin counterfeit you must find multiple things wrong with it. (i.e fatty details, spikes, toothy denticals, depressions, weak detail, etc)

[Oldtrader3]

My guess is that some counterfeit dies were produced with a Pantogragh stylus milling machine. This technology would most likely render any small contact marks on the original coin surface as round depressions on any coin die. Dies made from a steel mold cut by pantograph cutter would not be fine enough to exactly reproduce the shape of the contact mark in the coin, so the mill cutter would make a small round depression. This depression would punch a small raised dimple in the struck coin from these dies.

 

Additionally pantograph machines, if not run by an expert machinest are not precise enough to reproduce sudden, sharp elevation changes, such as the talons or arrows, without leaving excess material which would be a raised area adjacent to the talons or arrows when struck on a reverse image coin. Third-world counterfeiters are not going to have basining machines to polish the dies and remove filets (radiuses) in the raised reliefs.

 

Please excuse the editing but I have been retired for several years and, along with illness, my brain is not as facile as it once was.

[stinkycheese1]

My guess is that some counterfeit dies were produced with a Pantogragh stylus milling machine. This technology would most likely render any small contact marks on the original coin surface as round depressions on any coin die. Dies made from a steel mold cut by pantograph cutter would not be fine enough to exactly reproduce the shape of the contact mark in the coin, so the mill cutter would make a small round depression. This depression would punch a small raised dimple in the struck coin from these dies.

 

Additionally pantograph machines, if not run by an expert machinest are not precise enough to reproduce sudden, sharp elevation changes, such as the talons or arrows, without leaving excess material which would be a raised area adjacent to the talons or arrows when struck on a reverse image coin. Third-world counterfeiters are not going to have basining machines to polish the dies and remove filets (radiuses) in the raised reliefs.

 

Please excuse the editing but I have been retired for several years and, along with illness, my brain is not as facile as it once was.

 

That makes sense. But what you're talking about are raised pimples on a coin right? Not circular depressions on the coin?

 

[Oldtrader3]

Circular depressions cut by the pantograph on the die because of contact marks would be raised dimples on the struck coin. The pantogragh reverse machines the dies into the steel so raised relief is machined sunk into the die, therefore depressed nicks are machined as raised in the die which will strike small round dimples. However, raised edges of displaced material in nicks would be round, raised pimples. You are essentially correct.

[RWB]

Nope.

A reducing lathe, such as the old Janvier, normally produces a positive hub from a positive original. Also, if the equipment is so poorly used and maintained as to convert irregular or oval “small contact marks” into round ones, then it would also distort the rest of the design in a similar manner. The result would be grossly warped and any coins easily identifiable as fake at arm’s length.

[stinkycheese1]

Hmm. Do any of you hav bill fivaz's book on counterfeit gold? Prehaps you could look up this page: If you have the bill fivaz book, its page 149 on the reverse.

It says depression and tool marks in the field; depressions below eagles right claw and on center branch.

It's a 1906 liberty head $10 example 2

 

It's a depression that looks circular. There's many of them. Maybe you could understand what I mean then.

 

[Oldtrader3]

I am probably out in left field, but I was thinking about a machine similar to a French Portrait lathe that would trace and cut a die into steel from an actual coin surface. This die could be turned, hardened and used to strike coins which would eliminate the die hubbing process as these French Portrait lathe dies were employed to do in the 19th century.

 

Actually, there are probably several methods employed to make counterfeit dies. I certainly can not claim expertise in this area. I was only advancing a suposition. Probably most of these dies are made nowadays by an EDM machine with modelling software.

[RWB]

You are correct about the general pantograph theory; however, beyond the 18th century usage was positive-to-positive. This made it easier for the engravers to touch up the hub, then make a master die and work on it, then a master hub from which working dies were made. Depending on era and specific mint procedures, different parts of the work (lettering, shrubbery details, etc.) were done at different stages in the process.

 

(There’s a multipage description of the process, photo of a Janvier lathe and discussion about the cutting tools in Renaissance of American Coinage 1916-1921.)

 

[Oldtrader3]

I looked at the Janvier lathe process and read some writeups. Thanks for the information guys.

 

I was just thinking out-loud about modeling dies from a coin. IMHO, modern counterfeits are probably traced from an actual coin by a computer modelling stylus and have the female die made for hubbing by EDM machine cutting positive to positive. I wonder if the raised dots on modern counterfeits could be made by electrode erosion pits that are not polished off by properly basining the dies?

 

The Russian Mafia has the money and resources to buy any counterfeiting technology they need.