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Author Topic: Diameter of irregular coins with measure?  (Read 2704 times)

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Offline Lorenzo F

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Diameter of irregular coins with measure?
« on: May 30, 2020, 10:29:05 pm »
Dear friends, I would like to know if anyone at the Forum could help me with a question.

How to determine the diameter of old irregularly shaped coins such as many Roman pieces, where most of them are oval shaped.

Because in some auction and sale sites they inform the diameter as if it were regular as in modern currencies If someone could help me, in this doubt.

Thanks!

I attached a coin as an example.

Offline cmcdon0923

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Re: Diameter of irregular coins with measure?
« Reply #1 on: May 30, 2020, 11:47:31 pm »
I assume that if a single measurement is given, it is the "East-West" diameter.   But I have seen some descriptions where they list the "North-South" and "East-West" measurements, and if the coin is distinctly out of round, they will also list a "Maximum" diameter.

Joe deals with this all the time, so let's get his input.......


Craig

Offline Lorenzo F

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Re: Diameter of irregular coins with measure?
« Reply #2 on: May 31, 2020, 12:11:46 am »
I really came to think of this east-west condition, even because I already saw some images having a ruler measuring in this position. But I am always in doubt which one would be correct. I believe that a diameter said to be correct serves as a parameter against counterfeiting

Thanks for your help

I hope that other friends can also give their opinions...

Offline Mark F

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Re: Diameter of irregular coins with measure?
« Reply #3 on: May 31, 2020, 12:29:29 am »
Just to see how a professional does it, I clicked on three random coins for sale at Forum. In the description of each coin, the width recorded is the "maximum width". That works for me.

Mark

Offline Mark F

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Re: Diameter of irregular coins with measure?
« Reply #4 on: May 31, 2020, 12:31:56 am »
Actually, the descriptions in Forum use "maximum diameter" NOT "maximum width", which is what I typed above.

Offline Joe Sermarini

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Re: Diameter of irregular coins with measure?
« Reply #5 on: May 31, 2020, 07:17:32 am »
When only one measurement is given, most dealers use maximum diameter.  Notice the word diameter is blue text.  All blue text links to more information.
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Offline SC

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Re: Diameter of irregular coins with measure?
« Reply #6 on: May 31, 2020, 09:10:05 am »
For any of my coins that are clearly not round I give two measurements based on widest and narrowest, e.g. 20x22mm.

SC
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Offline Dominic T

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Re: Diameter of irregular coins with measure?
« Reply #7 on: May 31, 2020, 11:14:51 am »
I believe that a diameter said to be correct serves as a parameter against counterfeiting




Not really. It surely help for the exact attribution of a coin. Maybe you meant "die axis" which can be a clue for recognizing counterfeit. The weight is also very important in that matter.
DT

Offline Lorenzo F

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Re: Diameter of irregular coins with measure?
« Reply #8 on: May 31, 2020, 05:21:49 pm »
Hello, yes I expressed it wrong, you are correct, using the matrix axis as a parameter can help to detect forgery.

Many thanks to all friends who helped me in this doubt.

Best regards!

Offline PtolemAE

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Re: Diameter of irregular coins with measure?
« Reply #9 on: June 01, 2020, 10:03:53 pm »
Dear friends, I would like to know if anyone at the Forum could help me with a question.

How to determine the diameter of old irregularly shaped coins such as many Roman pieces, where most of them are oval shaped.

...

What harm can come from measuring both minimum and maximum diameters? It takes only a second or two longer to measure both. Maybe it will become universal practice at some point to always state both minimum and maximum diameters as well as weight and die axis. Few ancient coins are perfectly round and many diameters vary by more than 10% and the weight and die axis aren't easily conveyed by photos.

PtolemAE


 

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