Doug
Full Version: reddish/copper spotting on gold coins
I'm wondering whether a slight copper content would cause this reddish tone shown at about 4 o'clock in this picture? Why do some gold coins get this, while others don't; manufacturing process, or does the color show up over time, or some other reason? just curious, thanks!
Doug
Doug
QUOTE(Doogy @ Mar 23 2006, 01:27 PM)
I'm wondering whether a slight copper content would cause this reddish tone shown at about 4 o'clock in this picture? Why do some gold coins get this, while others don't; manufacturing process, or does the color show up over time, or some other reason? just curious, thanks!
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Yes, it would be the presence of another metal in the alloy. The way the alloy was made and mixed does play a role. There's plenty of Greek staters with no such issues.
QUOTE(jlueke @ Mar 23 2006, 12:16 PM)
Yes, it would be the presence of another metal in the alloy. The way the alloy was made and mixed does play a role. There's plenty of Greek staters with no such issues.
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thanks for the explanation, it certainly makes sense. You used the word "issue", which i'm wondering about. If this type of spot shows up on a gold coin, do the third party graders (in this case, ANACS) see it as a flaw and thus would grade it lower?
Doug
QUOTE(Doogy @ Mar 23 2006, 02:18 PM)
thanks for the explanation, it certainly makes sense. You used the word "issue", which i'm wondering about. If this type of spot shows up on a gold coin, do the third party graders (in this case, ANACS) see it as a flaw and thus would grade it lower?
Doug
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Doug
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That I do not know. I suspect they probably market grade this somewhat. So if there is a date/year/mint combo where this is common it is probably factored into the grade. If this is an abberation one would suspect they might knock off a point or two.
This is what is known as a copper spot (or carbon spot), and it is usually caused by a higher concentration of copper in the alloy at that particular spot which has oxidized over time. For the most part grading companies tend to ignore them, though on common dates they likely result in a downgrade of a point or two. In rare cases when the oxidation is extreme, some grading companies will body bag the coin for environmental damage. Hope this helps.
QUOTE(jtryka @ Mar 23 2006, 01:20 PM)
This is what is known as a copper spot (or carbon spot), and it is usually caused by a higher concentration of copper in the alloy at that particular spot which has oxidized over time. For the most part grading companies tend to ignore them, though on common dates they likely result in a downgrade of a point or two. In rare cases when the oxidation is extreme, some grading companies will body bag the coin for environmental damage. Hope this helps.
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Great! thanks for the info!
Doug
The copper spotting is an alloy anomaly, not that uncommon. That's a beauty of a gold eagle, regardless of the spotting. Congratulations on a good buy.
Until a couple of years ago I owned a 1928 Dutch Ducat that had a large red spot on it, similarly. It was just an impurity in the metal.
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