Beware of rainbow toning

Incredible.

 

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Astounding

 

Mesmerizing

 

One of the things I often do for Christmas in the lab is to make a spiral of copper wire and suspend it in a beaker of silver nitrate solution. The wire will continue to react with the silver nitrate and make a Christmas tree of glittering silver crystals and the solution will turn blue due to the copper nitrate being formed.
Copper is more reactive than silver, but is still not considered a REALLY reactive metal (elemental native copper can be found pure in nature).

 

So what other things will react with silver that are found in ambient atmosphere or in typical coin storage options?

 

Against my better judgment, I come back to this thread...

But it also doesn't mean that it can be done either. It is a logical fallacy to conclude otherwise. What you and some of the other posters seem to struggle with is the mere fact that you have an opinion, does not necessarily mean that it is accurate and will come to fruition. And since the thread was taking a position that rainbow toned coins should presumably be avoided because of concerns of artificial toning, the burden of proof or onus is on you. I don't think there is anything unreasonable about asking for some sort of proof when broad pronouncements are made that any pattern of toning can be replicated with great fidelity.

And to be clear, I see the logic above in red being used in your toning comments generally, and am not targeting the dipping of copper. I have not and do not intend to reread the last several pages to catch up on the aside.

We are. To be clear, when a toned coin comes to market, it is not assumed that is natural. Rather, we look to objective indications on the coin itself.

This is false. PCGS discontinued its color designation guarantee protections, but NGC still guarantees the color of copper for 10 years from the date of encapsulation.

It is possible that dipping or even something more severe could be at play in some instances. There are many chemical manipulations that can be made to copper. One them is applying cyanide compounds. It will strip the coin at first, but it will reoxidize and tend to have a golden red color about it in time. These do end up in TPG plastic.

So we at least agree that your reasoning is the same.

I actually don't disagree with this part, but there are still clues to look for in the toning. You are not viewing each area of toning in isolation, but reviewing the totality of the evidence.

There are indicators that indicate that a coin is likely NT and there are indicators that the coin is AT. This is also where market acceptability comes in. The less certain one could theoretically be in regards to a coin, the less market acceptable and less liquid the piece will be. And even accounting for "iffy" pieces, their existence does not say anything about the ability to reproduce blatant NT coins. I have never seen, but would love to see, a coin doctor replicate pull away toning or textile toning for instance.

 

First, let me say that I agree with you but David posted a bunch of coins a few pages back asking which were AT and which were NT. One of the coins that he showed and claimed was AT shows pull away toning.

My take on this coin is that the photo is badly oversaturated that there is no way it actually looks like that in hand. That said, even if those colors are much different than the photo, at first glance, it looks like it would have to be an artificially toned coin. What is your opinion of this coin?

 

Great information on rainbow toned coins. Thank you!

 

I didn't see this particular coin as it was at a point where I tuned out. I would like to see better photos of the coin, but based on the images I do not believe it to be original either. Fair is fair though. Regardless, I don't think someone would be fooled by this piece and I would be shocked to see it in top TPG plastic if it looks anything like that in hand.

Edited: I also wonder if this piece had started toning naturally on its own and then was helped along as brought up by another forum member in a hybrid scenario. In this case the rest of the coin does not follow what is expected, so again, under a holistic approach, I think it is still consistent with position that both of us have assumed throughout this thread. On the other hand, if the pull away effect did result from an AT process (instead of an AT process applied over existing patina that was natural), I find it absolutely fascinating.

 

Speaking of pull-away toning as an indicator of NT, Even after reading the various threads over on the other forum. I have not seen a good physical/chemical reason why it only is on NT, a lot of theories, but none that seem reasonable to me.

 

I would like to know also, as the other main colored silver compounds~ oxide, carbonate, etc. are produced by lab reactions, not in the atmosphere, and I doubt in coin storage.

 

The most common theory is that the minting process creates areas of localized strain hardening around the stars and lettering and that at some critical point, the number of dislocations created from plastic deformation in some way inhibits corrosion in conditions that will cause the remainder of the coin to form a thin film interface. Of course, this also requires that whatever corrosion resistance is caused by the strain hardening can be overcome by accelerating the toning process as is done in artificial toning methods.

I have researched this topic in the past on the internet, but most of what I have found is contradictory to the theory. What I have found states that a higher dislocation density should increase diffusivity rates and actually increase the susceptibility to corrosion. However, even in those articles, I usually find a quote like this:

An Investigation on Dislocation Density in Cold-Rolled Copper Using Electrochemical Impedance Spectroscopy

And since Silver is not typically used in engineering applications, it is exceedingly difficult to find any research done on the formations of thin film interfaces on silver. I have often considered contacting my alma mater to suggest this topic for a graduate level thesis topic in the Materials Science department but I just never get around to doing it.

 

Aren't most of the other silver reactions achieved in aqueous solutions?

 

The energetics for the reactions usually involve silver nitrate ( formed using nitric acid) . Silver oxides formation usually involve hydroxides not usually even a minor component in the air moisture or ground water. Similar products that could contain silver, I can't visualize being a factor in toning due to the chemistry, unless a DuPont warehouse exploded in a thunderstorm. Silver compounds usually aren't very soluble in water with a normal pH. Silver-organic compounds are more soluble in water,and thus body fluids/tissue, such as bandages, antiseptic for strep throat before antibiotics. I think that sulfides or other sulfur compounds would account for almost all silver toning.

 

how about this one?...

 

Looks 100% original to me based on your pics.

 

What I find most interesting with toned copper is how proof coinage of the early 1960's (say from 1960 through 1964, but peaking in 1961) seem to exhibit more vivid colorful rainbow toning inside sealed original cello packs than any other era (what I have seen at least).

I can go into almost any bricks and mortar coin dealership and ask to pick through their 1961 cello pack proof sets and find some brilliantly toned 1961 Proof Lincolns. I know that there was nobody in the back of that dealership trying to artificially tone these since ALL these sets (the untoned ones and the few with toned coins) are all being sold at the same low price and not being marketed for profit (typical price is around $25 for the entire 90% silver proof set).

So there is something about proofs in the early 1960's ... either by the way they were manufactured or post processed at the mint before sealing ... or perhaps in their copper alloy content (maybe there were trace impurities in the zinc copper alloy in the early 1960's? Not sure) that caused (some) proof coinage of that era to tone brilliantly inside the mint sealed cello. I am 100% absolutely convinced these coins are all NT (naturally toned) since I see this occur over and over.

Here is a 1961 Proof Set that I bought from my local bricks and mortar dealership for $25. And underneath the PCGS TrueView photo (PCGS PR67RB) of that same Lincoln after I cut it out of the cello and submitted it.




Some people might look at this coin and say "how can that color happen naturally" -- but I saw this coin from cello pack at my local dealer who was selling it along with hundreds of other sets with untoned red lincolns.

Next is a 1962 intact OGP cello pack proof set that I bought off ebay for $25 (which is a $0 premium over a "dime a dozen" untoned set) -- and when I cut out the Lincoln and submitted it to PCGS it came back PR68BN (one of only three (I think) PCGS PR68BN Lincolns known to exist for the entire Lincoln series).





So sometimes the wildest looking colorful copper coins can be completely NT (naturally toned).

I know about these two particularly because I saw exactly how they were marketed and sold (for $0 premium) and hardly even a mention of the toned Lincoln -- and the state of the OGP mint cello pack (which were pristine with no pin holes).

Here are a few more wildly colorful 1961 Proof Lincolns. I think the grades were PCGS PR67BN, PR67BN, and PR66BN.




This also extends to Jefferson Proofs -- where monster toned Jeffs in the 1960-1964 era are almost common (well not quite common, but more common that other dates). Since Nickels are 75% copper, I guess this makes sense -- so whatever process affected the Lincolns in this era also in some cases extended to the Jeffersons.

 

What happened in 1970 with all the bulls eye toned cents? Something with alloy or plastic?

 

I have a number of Red copper Lincoln's in PCGS slabs that are toned. I know for a fact these were in that condition when slabbed because I sent them in raw for grading. My point being these didn't turn in the holder.

65RD


66RD


67RD


65RD


65RD


PR66RD CA