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 Replies: 8 / Views: 1,595 |
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New Member
Netherlands
6 Posts |
Hello, Recently I have bought this coin, it is a common bronze coin from Lyme. However there has been a debate among collectors about the unusual crystallization presents on the surface, see the coin below with some of the spots marked:  The weight of the coin is 3.20g, diameter 15mm. Now I have found from the same seller another coin which shows this even more severely, and maybe it is better visible for some people what I mean:  You need to zoom in the picture to see it more clearly. It also worries me that from the same dealer there is a different coin with the exact same style of color and this weird 'crystallisation'. Opinions are appreciated a lot, I am actually clueless and kind of worried, what could it be? Thank you. |
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Moderator
 United States
23731 Posts |
If both these coins can from the same dealer, they might have used some type of chemical to clear them which also etched the metal.
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New Member
 Netherlands
6 Posts |
Thank you for your response. You do think the coins are authentic though? Someone told me that casted bronzes can crystallize. However I really doubt such a common coin is counterfeited.
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Moderator
United States
23731 Posts |
IMO they are both genuine.
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Pillar of the Community
United States
613 Posts |
As a chemist, I would not call this crystallization. Rather I would call it striation (lines in the metal surface). Sorry, I don't know what would cause this.
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Pillar of the Community
United States
3382 Posts |
It has always been my suspicion that this is caused by moisture in the oxidation of the surface.
The coin was "cleaned" down to the metal surfaces and the course and unattractive layers removed.
Usually the patination layers of 2,000 years is quite attractive
But sometimes not so much
The conservator decided they were better off removed and we are seeing what lay beneath
But this is only my supposition
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Bedrock of the Community
Australia
21602 Posts |
Metallic crystallization is much less of a problem with ancient copper / bronze coins, than it is with high purity ancient silver coins.
For good illustrations, refer to Google Images for
silver crystallization ancient silver coins.
Horn silver deteriation for ancient silver coins is also worth a Google Images investigation as well.
I don't think there is a major problem in this regard with this coin.
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Pillar of the Community
United States
1554 Posts |
The surface marks visible in the photos remind me of the rippled artificial luster on modern coins which have been "whizzed" with a rotary brush. My suspicion is that these coins have been mechanically cleaned with the aid of a Dremel or similar rotary tool.
Edited by Kushanshah
10/05/2018 2:32 pm
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Valued Member
Canada
167 Posts |
Guys For past few years I always thought crystalization is a good indication of authenticity because I read few places and told by few dealers that its very hard to fake crystalization until I found few fakes that has been crystalized and now all my assumptions crumbled away. Please look at this highly crystalized coin which is cast fake. I wonder how they did this ? I appreciate some expert opinion on this for me to learn too. https://www.zeno.ru/showphoto.php?photo=185191 |
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Replies: 8 / Views: 1,595 |
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Posted 10/02/2018 5:11 pm
