Discussion in 'World Coins' started by moneditis, Jan 19, 2015.
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Doubt about this columnario
More here https://moneditis.com/2017/02/07/reales-deaocho-varios/
Adding a couple
Not an uncommon phenomena in the coining of Spanish colonial coins. It is related to improper cooling of the molten silver alloy, or to an improper alloy.
Further explanation in the following link (sorry- in spanish)
Explains a lot, great link. Last question, does it detract/reduce numismatic value/collectability or is it a non-issue. I live in Spain and see it a good bit but have steered clear as am uncertain.
Thanks for the link! I'm always looking for non-English language forum sites and sources of coin information.
Good question. For me it would depend how badly the coin is affected. For example, how extensive the fissures are, and whether they affect both obverse and reverse.
In my experience, they usually only affect one side of the coin and are restricted to a relatively small area of the planchet. In this case I do not see it affecting the value much.
Another important point: plata agria is considered to be proof the coin is genuine.
It is thought counterfeiters would find it very difficult to fake this feature convincingly. Therefore, a coin showing this is generally considered to be genuine.
That is a very nice 8 reales pillar dollar. Unfortunately, I found out about the Jesus Vico auction to late to register, perhaps next time...
@Nathan401 - could be prolonged corrosion, or could be a poorly made counterfeit. Hard to tell without seeing it in-hand and running tests.
Here's my recent eBay pick-up for under $300. PCGS AU58 with currently no MS examples certified there for that date. It's probably darker in-hand than the glamour shots from their imaging department, but knowing PCGS the luster should be all there. It's in transit to me right now.
Will be replacing my existing 1793 AU53 example I picked up back in 2011.
Oh, it's authentic. And yes, lots of saltwater corrosion .
01mikep - Its silver surface embrittlement which is caused by the stress of copper and silver in the same alloy. I discuss this in my new book Forgotten Coins due out this summer. Its normal environmental factors acting on the coin. It has nothing to do with an improper alloy mix or other type of error in manufacturing. Could be inhibited due to annealing. On this fact still not clear to me.
Nathan - agreed. Could be either counterfeit or salt water corrosion but since its a 1783 Carolus III I am 99% certain its salt water corrosion since it was THE MOST common date in the Calzador Wreck.
See Robert Gurney's book on Counterfeit 8 Reales at Amazon Books to assist you in easily identifying Portrait Counterfeits with other information. At least view the Table of Contents and then decide. Good luck ...
1. What is the link to your homepage. The links to the posts above take me to only the single coins.
2. what is the name of your book?
Eduard, posted: Another important point: plata agria is considered to be proof the coin is genuine. It is thought counterfeiters would find it very difficult to fake this feature convincingly. Therefore, a coin showing this is generally considered to be genuine."
While this was true in the past, it is not anymore as even some crude fakes show stressed planchets with this characteristic.
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