Toning: A Thing Of Beauty?

Silver is usually the ones that tone beautifully like Morgans. Peace dollars do not tone well because the way the planchets were prepared before striking, it is hard to find a beautifully toned Peace dollar. Gold will tone but its not as reactive as silver is, copper turns brown and can also tone but seems like silver is more apt to tone from the environment easier than any other metal. Kind of like a silver candle holder that tarnishes when left out or even stored where the air can get to it easily

Peaceman, I assume that you are not referring to me, or maybe have me confused with someone else. My name is not Luke. I do like world coins though.

Thanks very much bio and Bryan. Excellent explanations and photos, which lead me to further questions:

In reference to silver, 'the way the planchets were prepared before striking' is a very interesting notion to me. I am rather ignorant of this concept. Would this be associated with the strip rolling, annealing, tallow application, sulfuric acid dip, and riddling? It seems to me that if it were a matter of specific density, weight would become an issue.

Yes, I have considered the word 'toned' may be just a nice short word for 'tarnished'.

Would the planchet preparation difference between the 1921 Morgan and Peace dollars of the same year also explain the stark contrast in the ratio of DMPL and PL examples to be found today between Morgan & Peace?

I had rather assumed that die preparation played a major role in all of this, but your explanation is quite sensible. To achieve a high level of toning, a less granular coin is optimal? Possibly toning and PL surfaces somehow compliment and are dependent upon each other?

I have seen the term ' nice chocolate color' referred to when advertising copper coins. I had presumed that this was in respect to toning? I have doubts now that it just may be inherent in the aging of the element 'copper'.

Oh, I see buck, thanks for the interpretation. Star Wars came out before I was born, and I never saw the movie or got into the fad. (This causes the post to become even more of interest to me however. Was it something that I said)?

biokemist6,

I was looking at the 1950D I recently bought from you and I noticed it was starting to tone. I like it.

Wornslick

Excellent Bryan !! A most excellent explanation.

While "dirt" is foreign material that has somehow or other become attached to the coin's surface, from a chemistry point of view, there is no objective difference between "toning", "tarnish" and "corrosion". What coin collectors call "toning" and antique dealers call "tarnish" is really just a very, very mild form of corrosion.

The Earth is not a very friendly planet for a numismatist. Our highly reactive mixture of atmospheric gases means that bright shiny metal does not, except for gold and certain rare platinum-group metals, occur naturally. From the moment a coin is struck, the Earth's environment is doing it's best to turn that coin back into the minerals from whence it came. In my opinion, it is our job as numismatists to try to slow this process down as much as possible.


The two types of toning on a silver coin are caused by the exact same chemical process: reaction with atmospheric sulfur compounds, such as hydrogen sulfide. Intrinsically, they're the same. The aesthetics, however, are different; the "coin doctors" try to imitate the "naturally occurring" toning colours and patterns. The "bad" coin doctors fail, miserably. The "good" coin doctors that have worked out a method of making "market acceptable" toning are probably getting away with it.

It's kind of like comparing a Van Gogh painting with a paint-by-numbers I did when I was ten. Both are "intrinsically the same", just splotches of paint on a canvas. But people will pay millions for a Van Gogh (or a well-made fake Van Gogh), while my childhood artworks are valued by no-one except my mother. The difference is all in the aesthetics.


Pure gold won't tone; not unless it's been exposed to an atmosphere much more reactive than ours. The .900 fine alloy used for American circulating gold coins will tone slightly, due to corrosion of the copper diluent. But if you could bury a .999 fine gold bullion coin in the ground and dig it up a few million years later, it would still look the same.

Silver is almost as chemically unreactive as gold; it'll take a long, long time for a silver coin to turn back into silver ore. This is mainly because metallic silver does not readily form silver oxide by reacting with air; you need to hit it with something wierder, like ozone. Sulfur is one of the few things it will react with, forming dark-coloured silver sulfide tarnish. Chlorine is another; silver chloride, or "horn silver", will turn a silver coin greyish-white. Chlorides can't get airborne as easily as sulfides, so silver chloride formation is only a problem in salty places, like near a windy seashore, or if a coin is buried in salty soil, or if lost at sea (eg. shipwreck salvage). In short, while a silver coin will easily "tone", it won't easily "corrode".

Other metals, suck as copper, zinc, nickel, iron, and the exotic alloys many modern coins are made of, are all much more reactive than either silver or gold, especially with other elements in the atmosphere such as oxygen. Coins made of these materials can develop thin films of corrosion just like a toned silver coin, but this toning is usually just the first step on the way to corrosion and eventual full mineralization. A "chocolate-coloured" copper coin has a nice thin layer of copper oxide on it. Ancient copper and bronze coins that have been buried in the ground for 2000 years often have a "tone" or "patina" that can be more than half the thickness of the actual coin, with only a small core of actual metal remaining.

So in short, "silver toning" is more usually found, and more usually talked about, because it's a lot harder to stop the corrosion process for a base metal coin at just the right moment to create "toning" before it evolves into full-blown "corrosion". The number of otherwise "nicely toned" copper coins that are starting to turn green can attest to this.

this thread makes me want to find a nice toned coin haha