Author Topic: Traces of Modern Machines on Coins - 5 Tremissis from eBay (Read 4177 times)

gibfrog · « **on:** July 15, 2007, 12:51:52 am »

xxxxxx

vitellivs · « **Reply #1 on:** July 15, 2007, 06:52:26 am »

great post!

Jerome Holderman · « **Reply #2 on:** July 15, 2007, 08:12:22 am »

Thanks to Dr Prokopov for providing this valuable detection tool.

Unfortunately for me, after reading the article, I examined some coins in my personal collection and have found what I believe is this type of forgery.

Maybe I'm over reacting and the lines above the E on this coin are just flow lines? But they look very suspicious to me after looking at the pictures in Dr Prokopov's article....

Do the members of this good Forvm agree, that this coin must be moved to the dreaded black cabinet

Jochen · « **Reply #3 on:** July 15, 2007, 08:36:41 am »

Dear Jerome!

Comparing your pic with the pics of Dr.Prokopov I see an important difference. On Dr.Prokopov's coins the traces are always on the slope of the letters whereas on your coins these lines are on the flan itself. I think this is an important difference!

Best regards

Ilya Prokopov · « **Reply #4 on:** July 15, 2007, 08:48:32 am »

Jerome,
can you please upload photo of the other side of this coin?

Jerome Holderman · « **Reply #5 on:** July 15, 2007, 09:09:39 am »

Certainly,

Here is the obverse:

Hydatius · « **Reply #6 on:** July 15, 2007, 09:18:14 am »

This is good stuff, and useful ammunition for condemning other coins produced in this manner that may turn up in the future, but it is worthwhile pointing out that the overall style of the tremisses under discussion is so bad that no one who has any familiarity with these coins would ever be taken in by them. They look like junk.

Richard

Ilya Prokopov · « **Reply #7 on:** July 15, 2007, 11:55:57 am »

Jerome,
I cannot be sure without seeing the coin itself (and especially the edge), but I think this is a trace of hand work. I will keep this coin in my mind.

Robert_Brenchley · « **Reply #8 on:** July 15, 2007, 06:13:55 pm »

The fields on Jerome's coin look authentic, while those on the fakes have a totally flat, 'dead' look. An engraver could easily leave marks like those.

rick fox · « **Reply #9 on:** July 18, 2007, 08:41:19 am »

Dr.Prokopov - I hope you don't mind me using one of your pictures to ask a couple of questions.

1. Your discussion in the article is about tool marks that I have highlighted with red squares. Is this correct?

2. What causes the areas marked with blue squares?

Thanks

Rick

Ilya Prokopov · « **Reply #10 on:** July 19, 2007, 02:30:30 am »

Rick,
The core was not produced by the original method. This can be seen especially on the coin edge - there are sharp roughnesses and caverns.
Also, the coin is of nonquality gold (different from the ancient).
When making the core, there were many lapses, because of the production method. The original coins were made by a single hammer strike when heated. However this coin was made by slow pressing on the cold core. This resulted in such caverns.

rick fox · « **Reply #11 on:** July 19, 2007, 04:13:13 pm »

Dr. Prokopov are the red squares above, tool marks from the counterfeit dies? Is this something that is common to counterfeit dies?

Scipio Helveticus · « **Reply #12 on:** July 19, 2007, 04:47:27 pm »

And...erm...what happened to Cliff's post??

Douglas · « **Reply #13 on:** July 20, 2007, 12:59:48 am »

Apparently Cliff thought better of his post. This has been educational just the same, and I am glad of Dr Prokopov's involvement here.

vitellivs · « **Reply #14 on:** July 20, 2007, 08:24:13 am »

Quote from: Ilya Prokopov on July 19, 2007, 02:30:30 am

Rick,
The core was not produced by the original method. This can be seen especially on the coin edge - there are sharp roughnesses and caverns.
Also, the coin is of nonquality gold (different from the ancient).
When making the core, there were many lapses, because of the production method. The original coins were made by a single hammer strike when heated. However this coin was made by slow pressing on the cold core. This resulted in such caverns.

Mr Prokopov,
can you explain difference (and maybe show some photos) between caverns on fake gold coins made by pressing and caverns on genuine gold solidii occured because of impurity of gold.
Thank you in advance.

Reid Goldsborough · « **Reply #15 on:** July 20, 2007, 01:15:51 pm »

Quote from: Scipio Helveticus on July 19, 2007, 04:47:27 pm

And...erm...what happened to Cliff's post??

Looks like he stormed off, deleted his post here and posts in other threads too. Same kind of behavior in CFDL except there he deletes others' posts. I also agree that this new forgery detection techniquie is an interesting one, and thanks to Dr. Prokopov for pointing it out. It seems to me that there are two key diagnostics: 1) deep uniform cuts at the boundaries between fields and devices and legends and 2) tiny nicks at the boundaries between fields and devices and legends where the forger clumsily tried to soften or flatten the boundary.

moonmoth · « **Reply #16 on:** July 20, 2007, 05:42:38 pm »

Looking at Jerome's coin, I think the marks above the E and Y are "flow" marks. These are caused when the movement of metal across the surface of a die, repeated many times during striking, gouges small channels into the die's surface. Subsequent strikings show these raised lines in the field. This is a common phenomenon on Roman denarii and antoniniani.

There is also a hint of very shallow parallel lines running diagonally downwards from right to left across the field. This looks to me like the result of some enthusiastic cleaning.

Bill Welch

monipro · « **Reply #17 on:** July 23, 2007, 03:54:19 am »

Dear all,
Dr.Prokopov asked me to appologize on his name for being silent these days. He is off to a small vacation and will be back in the end of this week.
Best regards!

vitellivs · « **Reply #18 on:** July 30, 2007, 04:55:28 am »

Quote from: vitellivs on July 20, 2007, 08:24:13 am

Quote from: Ilya Prokopov on July 19, 2007, 02:30:30 am
Rick,
The core was not produced by the original method. This can be seen especially on the coin edge - there are sharp roughnesses and caverns.
Also, the coin is of nonquality gold (different from the ancient).
When making the core, there were many lapses, because of the production method. The original coins were made by a single hammer strike when heated. However this coin was made by slow pressing on the cold core. This resulted in such caverns.

Mr Prokopov,
can you explain difference (and maybe show some photos) between caverns on fake gold coins made by pressing and caverns on genuine gold solidii occured because of impurity of gold.
Thank you in advance.

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Author Topic: Traces of Modern Machines on Coins - 5 Tremissis from eBay (Read 4177 times)

gibfrog

Scipio Helveticus

Douglas

monipro