double rim 10 eurocent

[andrea78ts]

How is this double rim caused?
It doesn't seem to be neither a collar clash nor a finned rim...

[diamond]

I've seen this form of double rim in fractional Euro coins, coins from Thailand, and one other country that I can't recall at the moment. The internal "rim" is really a circular ridge that is not part of the original design. You'll notice that peripheral design elements continue on top of the ridge. The only explanation I can come up with is that it's an unusual form of die deterioration/deformation. The amazing regularity of the ridge is a deep puzzle. However, since ridge formation occurs among different Euro coin denominations and countries and in countries not part of the Eurozone, unintended deformation in the die steel would seem to be the only explanation.

[diamond]

Ridge formation in U.S. coins (primarily copper-plated zinc cents) is always uneven and the ridges are usually broader. I'm wondering if some process other than die wear is responsible for the amazingly uniform ridges on these euro coins. Perhaps when the die neck is reduced to final diameter by lathing, this causes a circular valley to form in the die face if the die steel happens to be too soft. I'm just throwing out a wild guess here.

[andrea78ts]

Thanks for your reply. In italian coinage this kind of double rim is frequent, also before the introduction of euro

[diamond]

I never knew that. Do you have any other examples you could photograph for us? As I've been thinking of this problem I've toyed with other possible causes. It's possible the deformation takes place during hubbing, perhaps if the working hub is too soft. Many of the affected coins show no other signs of die deterioration (orange peel texture, redial flow lines, concentric flow lines, bloated letters, etc.), leaving open the possibility that the ridge is present at installation. I've also not seen any progressive worsening of the ridge, something else that would be expected if this was merely die deterioration.

[andrea78ts]

Sorry for the delay in my reply.
Please see and another example of double ring Italian coin.
This is a 500 lire with a double ring the internal plachet.
Andrea

[diamond]

What I see in your photo seems to be more of a step-down, as opposed to an elevated ring. I don't see a double ring. I am not sure that this is the same phenomenon as the rings seen in the fractional Euro coins as the purported ring lies well inside the design rim.

I submitted an article on rings to the weekly magazine Coin World in which I mention the Euro coins, along with Irish and Thai examples. I also cited your observation that the rings precede introduction of the Euro.

[diamond]

My column on raised rings in world coins is now available online:

http://www.coinworld.com/articles/so...-coins-remains

[andrea78ts]

Another example of Italian double rim (pre-Euro).
Andrea

[diamond]

Interesting. Is the ring present only on this face? This ring appears to have margins that are less clearly defined than the rings seen in the fractional Euro coins. It is also clearly associated with a late die state (worn dies). So in this case, I would have no trouble accepting the proposition that the ring is a manifestation of die wear.

[andrea78ts]

Yes the ring is only on this face