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Toned Coins

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Alright, I've been avid in the hobby for about a year now, and been on the boards here for about 2 months. Until I joined the boards I never even knew about toned coins, and the premium that is usually associated with them. I've been picking up bits and chunks of info with posts, but I'm still kinda lost on the whole world of toned coins, so I got a few questions...


1) How do coins become toned? I'm under the impression NT is from exspoure to oxygen over a number of years, and AT is from dipping. Adding, what kinda of solution is used for dipping, and when and what coins should be "dipped" as I often read.


2) Do all toned coins command a premium, or is it just select coins and certain types of tonning.


3) What is the best type of tonning. I've seen "toned" coins ranging from rainbow colors, to just a plain same color background, to coins that look like the tonning is dirt and tarnish.



And a question from personal experience. Before I knew about the dangers of cleaning coins foreheadslap.gif, I cleaned up a chuck of my early collection with a liquid solution known as "Connoisseurs Silver Cleaner". The container reads that it contains "Acified Thiourea" and a chemical known to cause cancer. After learning never to clean coins, and being pissed at myself for a few days I layed the coins out on paper towels in an empty side cupboard and forgot about them. I just noticed them the other day after about 6 months of sitting. When I pulled them out I noticed that some of them mainly my mercs, franklins, and 40% kennedys were developing either a yellowish toned rim, or a few that have a full blown rainbow.


Is this considered toning? Does this add any value to the coins, that I thought to have destoryed, or does it make them even worse? Anything else I should know about toned coins?


Thanks for your help in enlighting me. idea.gif

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Most toning is caused by hydrogen sulfide gas. Paper contains sulfur from the manufacturing process, hence many old coin albums would effect the surfaces of the coins contained because of chemical reactions with the sulfur contained within the folders. Temperature and humidity will determine the rate of these reactions. Because these are uncontrolled chemical interactions then the degree of toning can not be predicted with any amount of accuracy. This is what makes a true, eye-appealing toned coin something special since most normal tarnishing is quite blah and unappealing.


Intentional toning, on the other hand, can have somewhat predictable results. The chemical process is the same but is under a controlled environment. This is why many artificially toned coins actually have more eye-appeal than their naturally toned counterparts. These, however, are not market acceptable.


The different colors come about by the thickness of the toned layer on top. As light passes through this layer it is distorted and reflected off of the layer under the patina. The greater the thickness then the darker the color. This means that yellow/golden color has the least amount of oxygen=sulfur=silver=copper interaction so this allows the wavelength for the color yellow to appear. Then as more toning occurs then you'll get red, green, purple, blue and then, finally, black. Black is usually undesirable and once it reaches this state then irrepairable damage has already been done to the actual surface of the coin.


Since toning is a progressive process if the coin is not removed from the harmful environment then a once beautifully toned coin can actually turn ugly and dark. There are a few means to protect your coins from this. First one must consider the environment. Coins should be stored in a low humidity and a low temperatured environment and sealed from the atmosphere. There are products used to prevent the hydrogen sulfide gases found in the atmosphere from interacting on the contained coins. They do this by having either the holder or bag lined or impregnated with copper. This means that harmful gases will react with the copper first before devouring the coin. The holders are called Intercept Shield, which is the brand name. Some slabs have this feature. Another way to minimize toning is by placing the coin in a sealed plastic baggy and placing a nice, new shiny penny or two within. By sealing the bag, the amount of atmospheric gases are minimized and any that do enter will react with the pennies first. If the cents turn dark then you know that you have a bad storage environment. Replace the cents if they do turn with newer ones periodically.


So, some coins are pleasant and some are not. General consensus can pretty much tell an ugly coin but beauty is in the eye of the beholder. I've seen some toned coins that people rave over but I find undesirable so eye-appeal is subjective.


Originality is another related point. Most coins on their journy through time are possessed by many different collectors. This means that the possibility of being cleaned or dipped increases with each new owner. Which, in turn, decreases the number of original coins in the market. Some coins should be cleaned or conserved in order to improve the eye-appeal but it should be left to a professional such as NCS. But keep in mind that once dipped the originality will never be restored and the surface of toning which is stripped away actually removes part of the coin, never to return again. So, dipping a coin with blue or black toning will actually destroy a large part of the coin's surface which will remove the microscopic flow lines which causes luster. This will give the coin an artificial or washed-out look.


Also remember that as paint covers a multitude of sins so can toning. This is why many hairlined or lack-lustered coins are intentionally toned. This will make the coin more appealing to the novice who can not recognize the underlying flaws and will increase the sale price of the unscrupulous seller.


Thiourea is just the chemical agent used in most "dips" which strip off the toned surface by a chemical reaction. Usually if an untoned coin is dipped then thiourea will not actually affect the coin itself but can leave an unsightly residue. Also by wiping the coin after dipping can leave very ugly and unsightly hairlines upon the coin's surface.


Good question and hopefully Tom B. will chime in because he is the scientist and knows a great deal about the subject.

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It is not exposure to oxygen that causes coins to tone. Coins become toned when they are exposed to a chemical that is reactive with the metal that the coin is made of. This exposure can be in the form of a gas, liquid, or solid, and there are a number of different chemicals that can cause a coin to tone depending on the metal it is made of. For instance, sulfur is highly reactive with silver.


These chemical reactions cause a thin film to form on the surface of the coin which changes the way light is reflected from the coins surface, sort of like the way light is reflected through a prism.


Instead of the light hitting the coins surface and bouncing straight back to your eye, the light now has to first go through the film, hit the coins surface, bounce off, and go back through the film again before you can see the reflected light. This changes the spectrum of the light allowing you to see different colors depending on how thick or thin the film is at a given point on the coins surface.


AT or artificial toning and ‘dipping’ are two different things. Artificial toning is when someone purposely applies chemicals or heat to a coin in an effort to quickly tone it. People will usually do this for one of two reasons, either to try to fool someone into thinking the toning is natural, and/or to have the newly applied toning hide a problem such as hair lines on the coins surface.


Dipping a coin is the complete opposite of AT. Dipping a coin will remove toning. People usually will dip a coin to remove ugly, dirty toning. A commonly sold coin dipping solution is called Jewel luster. It is basically a solution of sulfuric acid and thiourea. Thiourea is the ingredient that is known to cause cancer.


As for what type of toned coins command a premium, well that’s a tough question because what one collector might like and pay a premium for, another collector may think is ugly and would not want to buy the coin at all, let alone pay a premium for it! With that said however, I will tell you how I feel about the issue of paying a premium for toning.


In my opinion, the only type of toning that is worth a premium is the true rainbow toning or solid color toning that is nice. In both types the color or colors should not be dark, and the toning should not interfere with the coins luster. IMO if the toning is dark, ugly, dirty, or interferes with the coins luster, it is not worth any premium.



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Thanks for the info everyone.


I don't know for some reason (probably the money value) I'd rather just get sparkling white gems. I have run across a few very very attractive toners, but just simply couldn't afford them.


I still am wondering though. Would a coin that say would grade VF - EF be more valuable left alone or AT. Or is just the preference of the buyer looking at the coin?

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It is all about the buyer and a the coin... Value books mean nothing.. It is only what people are willing to pay... alot of toning is crappy... and a really nice toned coin commands a premium just like a blast white one does.... since they are rarer

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I still am wondering though. Would a coin that say would grade VF - EF be more valuable left alone or AT. Or is just the preference of the buyer looking at the coin?
I have never seen a coin with really noticeable circulation that looked even the slightest bit decent with AT.


So long as the buyer realizes it's AT, it's likely to hurt the value in any grade.




PS- Even still, ruining a coin isn't worth it

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