Author Topic: Toned coins  (Read 2567 times)

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Offline dragondollar

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Toned coins
« on: June 02, 2011, 12:43:42 PM »
I'd like to have your opinion about this article I wrote about the differences with regard to toning, corrosion, surface damages between american and chinese collectors :)

http://www.dragon-dollar.info/chinese-coins-2/toned-chinese-coins/


Offline dragondollar

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Re: Toned coins
« Reply #1 on: June 02, 2011, 12:47:15 PM »
I had the idea to wrote it because of the characteristic fake toning in this topic.
http://china-mint.info/forum/index.php?topic=2959

By the way, fred63, would you allow me to include the picture of your coin as illustration?

Offline badon

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Re: Toned coins
« Reply #2 on: June 03, 2011, 12:39:11 AM »
Interesting article, but I don't think the contrasts between the Chinese and American markets are correct. You are comparing old coins in the Chinese market with modern coins in the American market. If you compare old with old, and new with new, you will find that both Chinese and American markets are very similar.

Beautiful toning is valued in both markets, and natural toning is valued even if it's not so beautiful, if it is old and original. For modern coins, excessive toning is a sign of abuse, so bright white, untoned coins are preferred.

The best toning is the kind that takes a long time to form, when a coin is properly stored.

Offline dragondollar

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Re: Toned coins
« Reply #3 on: June 03, 2011, 12:55:42 AM »
Well, I personnaly know several collectors of Morgan dollars or Trade dollars (which both have roughly the same age as late Qing chinese coins) who insist on flawless, mint state, white coins. I was thinking about them, since modern coins are not designed for circulation.

Also, buried (=corroded) coins can actually be sold for high prices in China if the underlying details are still good, while such coins would definitely be judged unattractive by american collectors, and probably not graded (juste Genuine) by PCGS or other grading companies.
« Last Edit: June 03, 2011, 01:10:48 AM by dragondollar »

Offline badon

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Re: Toned coins
« Reply #4 on: June 03, 2011, 03:05:56 PM »
That's a quirk about the silver dollar market, which is actually mostly perpetuated by hucksters selling overpriced coins to people who don't know much about the coins. About the buried coins, America doesn't have any history of buried coins. It's been a stable country for as long as it has had coinage, so the coins almost never got buried intentionally.

In China and Europe, with MUCH older coins, and MUCH more violent histories, coins were buried frequently. In fact, because of Europe's traditional handling abuse of coins, the only way to get old coins in reasonably good condition is to get them from newly discovered hoards of buried coins. Within 50 years, those coins well be pretty thoroughly trashed. Anything that isn't buried gets quickly destroyed by the collectors.

As far as I know, there are few, if any, very old coins that have survived in collector hands for more than about 200 years.

Also, China has traditionally used primitive casting techniques to produce coins. Those already have a poor quality surface finish, so a few centuries corroding in the mud doesn't make much difference.

One interesting thing is that's different between Europe and China is that Chinese coin and paper money owners are able to preserve their collections within their families for centuries, no problem.

In Europe, the only ones that MIGHT have a chance at preserving a collection for more than 200 years are the aristocracy.

In China, it's average, very poor, rural farming families that often have the oldest collections. Chinese families are probably the best in the world that I know of for handing things down as family heirlooms for hundreds of years. Well, China and the rest of the East, like Japan and Korea too.

Offline poconopenn

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Re: Toned coins
« Reply #5 on: June 03, 2011, 04:57:36 PM »
Here is a nice rainbow toned Morgan dollar with NGC star (*) designation. The buried coin will not generate rainbow toning since copper on the surface is oxidized and can not react with sulfur in the air. However, the silver still can react with sulfur to generate dark blue tone such as seen in circulated Imperial and Republic coins mentioned above. The mordern Chinese coin will not have rainbow tone since the copper content is very limited. I have seen many modern Chinese coins produced in 1980-1990 with a light blue tone in a doblue sealed package.   

Offline dragonfan

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Re: Toned coins
« Reply #6 on: June 04, 2011, 06:07:23 AM »
Hello,
Yes, nice coin poconopenn! Thanks for sharing. My 1989 Snake 15g Ag (90%), raw,  has a light and uniform brilliant shades of yellow toning, do you know if there is a specific ambient factor helping this happen? Thanks

 

Offline poconopenn

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Re: Toned coins
« Reply #7 on: June 04, 2011, 06:20:02 PM »
I had misstated in the last post. There are modern Chinese coins containing 10% copper, such as 15 gm lunar coins, can generate rianbow tone. In time, many silver coins with 10% copper developed a visible surface film of metal sulfide from 25 to 125 namometers thick. A yellow color identifies the thinnest film while the thickest film is black. Golden, reddish, purple and blue films lie in between yellow and black in their film thickness. Source of sulfur can be wooden and paper boxes, cloth bags, paper roll wrappers. Basement with high humidity is a good source of sulfur. One puff of cigarette smoke, exhaled at close proximity to a silver dollar will produce a light brown coloration, which deepens with each additional puff. The best reference book for coin tonning is "Coin Chemistry, Including Preservation and Cleaning" by Weimar W. White (ISBN 0-9713924-7-1, Library of Congress No. 2004106501), 2nd edition printed in 2006.

1989 snake appears to be the most susceptible to toning. Majority of snake (double sealed)sold at eBay had shown some degree of blue tone. In general, a better proof surface also can speed up the toning process.     

Offline badon

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Re: Toned coins
« Reply #8 on: June 04, 2011, 11:31:45 PM »
Excellent information poconopenn, thank you for sharing it.

Offline dragonfan

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Re: Toned coins
« Reply #9 on: June 05, 2011, 05:56:52 AM »
Yes I agree badon, excellent information poconopenn. So, a silver-copper alloy coin, normally and correctly protected and stored, over time could/will expose some toning traces, I understand this is a normal process, and each coin will react differently depending of its own environnement and composition. This is less the case for finer silver coins but could also happen.
From your standpoint, is this affect their numismatic value? Thanks again

Offline poconopenn

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Re: Toned coins
« Reply #10 on: June 05, 2011, 01:04:59 PM »
Current value of a nice rainbow toned Morgan dollar, such as posted above, will be more than double the white coin with the same grade. However, many toned coins are caused by finger print. Sweat from skin contains trace of sulfur, oxygen, chlorine, and water. Film generated from mixture of metal sulfide, metal oxide, and metal chloride can be ugly.   

Offline badon

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Re: Toned coins
« Reply #11 on: June 05, 2011, 01:35:34 PM »
The chlorides are especially bad because they can remain active even after the initial chemical reaction. That means they'll keeping "toning" your coin until there's more "tone" than "coin", and there's basically nothing left but a corroded piece of metal. That's just one reason why it's not OK to handle coins. No matter how gently you handle them, the chemistry will eventually wreck the coin even if you never touch it again.

They should remain sealed after conservation, to ensure the maximum survival lifetime - which could be thousands of years, if done properly. Future collectors and grave diggers will thank you :)

Offline dragonfan

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Re: Toned coins
« Reply #12 on: June 05, 2011, 05:09:49 PM »
I have learned more than expected from this topic :) ouch!
Thank you very much