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The Importance of Natural Toning on Early U.S. Coins

By Greg Shishmanian …..

Retired chemist and prolific numismatic author Weimar White is a purist representing one end of the spectrum regarding toning. His numismatic research and opinions are well known and respected, and this article does not dispute White’s chemical analysis of the oxidization process. Nevertheless, many numismatists passionately disagree with his conclusions regarding toning on early U.S. coins, as he equates any form of toning or oxidation as “wear”.

1798/7 Draped Bust Dime with original toning housed in an Intercept Shield holder. This coin was graded MS65+ by PCGS and is CAC approved. Image: CoinWeek.
1798/7 Draped Bust Dime with original toning housed in an Intercept Shield holder. This coin was graded MS65+ by PCGS and is CAC approved. Image: CoinWeek.

There are several simple and effective ways to slow the progression of natural toning. For example, in a book entitled Coin Chemistry, White suggests storing a few copper pennies with your silver coins to act as sacrificial corrosion targets. This method has proven to be an effective and inexpensive way to drastically slow the oxidization process. Reducing moisture is also important and can be accomplished by using a desiccant or a sealed plastic bag. Another good but more expensive solution is to use Intercept Shield storage containers which, the company claims, provide 10 years of effective corrosion protection. The inner walls of their containers are covered with a material containing copper that reacts with and permanently neutralizes corrosive gases. The shield acts as a moisture barrier and thus provides a dual form of protection that eliminates the two elements needed to form atmospheric corrosion.

A Liberty Seated Collectors Club 40th Anniversary Medal with simulated toning. Image: LSCC / CoinWeek.
A Liberty Seated Collectors Club 40th Anniversary Medal with simulated toning. Image: LSCC / CoinWeek.

Mr. White states the following in his article titled “Protecting your LSCC 40th Anniversary Medal”, published in the Liberty Seated Collectors Club (LSCC) Gobrecht Journal volume #117:

“Good coin care is very important since the tarnishing of silver is the oxidation of the silver, the loss of some of its electrons. There are two kinds of coin wear, physical wear and chemical wear. The tarnishing of silver is chemical wear just as when iron oxidizes to form rust in the form of iron oxide.”

Silver and copper are highly reactive metals, which means they easily lose electrons when they come in contact with other substances – especially oxygen, hydrogen, nitrogen, and sulfur. This explains why all silver and copper coins will tone naturally when exposed to the atmosphere. It should be noted that one important benefit of toning is that it serves as a protective barrier between the metal and the air that stabilizes the surfaces of coins.

The Impact of Storage on Toning on Early U.S. Coins

Early U.S. coins were not stored in a vacuum. They were exposed to and reacted with a wide array of elements in the air during wide-ranging temperature and humidity cycles. Coins were stored in many different ways and came in contact with many different materials over their lifetimes. Examples include wooden drawers and cabinets, cloth bags, leather pouches, paper envelopes and rolls, and cardboard coin holders.

A variety of environmental factors contribute to the toning of coins. Image: Adobe Stock / Stack's Bowers / CoinWeek.
A variety of environmental factors contribute to the toning of coins. Image: Adobe Stock / Stack’s Bowers / CoinWeek.

Wood stain and varnish were commonly applied to wooden drawers and cabinets. Oil-based wood stains contain ingredients such as petroleum, alcohol, formaldehyde, sodium hydroxide, and glycol. Wood varnish is made from three basic ingredients: solvent, resin or oil, and pigment or dye. These chemicals and materials react with the coin’s surface and subsequently affect the toning process.

Some of these storage methods will slow the toning process while others will accelerate it, but none of them will prevent toning over long periods. Mr. White’s article titled “Encapsulated Coins May Continue to Tone While in Their Holders”, published in the LSCC Gobrecht Journal volume #70, states:

“This is important information for the collector who wants to keep his coins in a state of “original purity” over a period of years.”

Liberty Seated Dollar (1840-1873).
Liberty Seated Dollar (1840-1873) by Weimar W. White.

What he omits is the crucial fact that toning has occurred to some degree on nearly all early U.S. silver and copper coins over the past 150 years. Therefore, this toning would have to be removed to achieve his goal of “original purity”.

In White’s book The Liberty Seated Dollar 1840-1873 (1985), he includes a paragraph entitled “The Thickly Toned Dollar Trap”. In it, he discusses the results of dipping thickly toned coins. He states:

“Those collectors who are bold enough to try cleaning these coins by dipping them in a sulfide removal solution are more often than not disappointed because they soon discover that they now have an About Uncirculated coin and consequently a financial loss.”

If you change the word “bold” to “foolish”, then White’s statement would be much more accurate. He fails to mention that dipping particularly thickly toned coins changes the surfaces of the coins.

The resulting metal loss and possible redistribution changes the flow lines and the way light reflects off the coin’s surface. “Flow lines” are defined as the microscopic lines on the surface of a coin created by the outward flow of metal during the striking process. This transformation of the flow lines changes the way we see the light that reflects off the coin surfaces. This is critically important and is referred to as a coin’s luster.

Instead of accepting White’s definition of “chemical wear” as the tarnishing of silver, it is more accurate to define the term “chemical wear” as the result of using chemicals to strip the layers of toning from the surface of a coin.

For years, White has claimed that toning prevents coins from having original surfaces and grading Mint State because they do not look the same as the day they were minted. He claims this is true for all coins regardless of their composition or when they were minted. White has even said that lightly toned coins should not be graded Mint State because of the chemical alteration of their surfaces, though he eventually modified this opinion to permit it when the toning is light enough that the surfaces can be unambiguously assessed to be free of physical wear.

Antique bottles. Image: Adobe Stock.
Antique bottles. Image: Adobe Stock.

Mr. White’s position is based on chemistry, yes, but he ignores the fact that real-life storage methods used over the past two centuries directly affected the toning process. His article entitled “How Some Carson City Coins May Have Escaped Heavy Toning” (Gobrecht Journal #65) attempts to justify his position by suggesting possible storage methods that would have prevented toning. His experiment consisted of placing a silver spoon in a blue Milk of Magnesia bottle with a closed screw cap and in a Nestle’s Toll House Morsels tin for about one year (the vessels representing possible bottle or tin types available 100-plus years ago). An assortment of bottles, glass hens, and tin containers, are pictured in this article as potential storage vessels. White concedes that the Shaker boxes shown would not give the best long-term protection from sulfur chemistry since they are porous and made of wood.

From this experiment in the above-mentioned article, he concludes that:

“The Carson City silver coins that today remain brilliant with full mint luster or bloom are few and far between. Is it possible that they were intentionally placed in covered containers to keep out the corrosive sulfur atmosphere? The experiment described in this article may provide a partial answer to this question.”

We’ve all heard the saying “anything is possible”. However, while one is unable to calculate the probability of White’s early Carson City coins being stored in a blue Milk of Magnesia bottle with a closed screw cap or a glass hen cookie jar for 150 years, one can be assured that it’s extremely low. In addition, these vessels are not airtight, and although they would likely slow the toning process, they would not prevent some degree of natural toning over long enough timespans. One only needs to look back at old-time collections and confirm the overwhelming number of toned early silver and copper coins.

The truth is that White’s opinion has contributed to people destroying the original surfaces of coins by repeatedly dipping them to remove multiple layers of natural toning. It’s alarming to see the toning on so many rare early U.S. coins permanently ruined by over-dipping from people attempting to produce white, untoned coins. Most early coins have already been cleaned in some way and have re-toned during their lifetime. Experience has proven that coins with natural toning and unmolested surfaces that retain some original luster are scarce and preferred by the vast majority of knowledgeable numismatists. As most numismatists mature in the hobby, their appreciation and desire to own coins that display these characteristics grows exponentially.

One wonders what storage methods and atmospheric conditions combined to prevent even a very small percentage of coins from toning. Regardless of how few survived, one is in awe of the magnificent beauty of frosty white early silver or blazing red copper coins that have retained their untoned, unmolested, lustrous, surfaces. The numismatic market recognizes their rarity and often places a strong premium on these coins.

Antiques such as paintings, sculptures, furniture, vehicles, and ancient artifacts, were made of many different materials. As with coins, nearly all antiques that were made of or contained reactive metals acquired toning (often called “patina”) and wear patterns over time. Very few of them look the same as when they were created. Their value is usually reduced significantly if they are restored to look like new. The vast majority of numismatists and antique collectors want examples that have survived with unmolested surfaces.

Respected senior numismatists have published articles on this topic. For example, Greg Reynolds is a numismatic writer, researcher, and analyst, and has explained the meaning and importance of natural toning. He has examined almost all of the greatest U.S. coins and most of the finest type coins and patterns. Reynolds has extensively researched the pedigrees of important numismatic properties and has written about and analyzed numerous auctions, private sales, and collections. He has contributed hundreds of articles to Numismatic News and other Krause publications and had a weekly column on

The Reynolds article entitled “The Basis for Collecting and Appreciating Naturally Toned Coins” is divided into three parts and contains a wealth of valuable information. It was published on in the fall of 2009. The following quotes are a few of my favorites:

“In the history of coin collecting in the U.S., most of the greatest all-time collections were characterized by many coins with attractive, natural toning, especially including many coins that had never been cleaned, dipped, or otherwise deliberately modified.”

Reynolds refers to the Eliasberg, Norweb, Pittman, and Garrett collections, calling them the four greatest collections to be auctioned over the last half-century. It’s no coincidence that virtually all the coins in these auctions displayed natural toning on their original surfaces.

He states:

“I always believed that most sophisticated and knowledgeable collectors, plus advanced dealer experts agree that usually, the naturalness and originality of the coin is a substantial and very important factor in determining the greatness and importance of a collection of U.S. coins.” He makes the following sage statements, “Rare coins with natural toning and original surfaces command respect among experts, have historical and cultural significance, and are satisfying to a knowledgeable owner. I emphasize the superiority of natural toning and/or mostly original surfaces.”

The professional graders at the major coin grading services have never endorsed or applied White’s philosophy that toning eliminates coins from being graded Mint State. A strong case can be made that coins that have been conserved by over-dipping or other methods of removing toning have been altered and can no longer claim to have original surfaces. Another problem is improper rinsing after dipping in an acid-based solution. This can leave contamination by products remaining on a coin’s surface.

Another well written article, “The Science of Dipping and Toning” by Thomas Bush (who has PhDs in both chemistry and biology), provides a detailed explanation of what dipping does to a coin.

There are some great articles on natural toning and patterns that include detailed color classification systems for natural toning. Doug Kurz developed a classification system that uses this color progression to concisely describe the toning on silver coins. He assigned classification codes to the colors typically found along the thin film progression. While there are infinite gradations and multiple possible color cycles that introduce subjective color assignments, our eye’s ability to see, process the reflected light, and distinguish certain colors is impressive.

1989-S Congress Commemorative Dollar with toning that has been determined to be artificial by PCGS. Image: CoinWeek.
1989-S Congress Commemorative Dollar with toning that has been determined to be artificial by PCGS. Image: CoinWeek.

Professional graders use the term questionable toning when they are unable to determine if toning is natural or artificial. Doug also notes that “artificially toned coins can still obey the standard progression, and there are also some naturally toned coins that do not. This can happen if there are unusual contaminants present during storage, such as chlorine, or excess sulfur. Such coins may fit our generally accepted notions of natural toning, while still exhibiting some unusual colors. But the vast majority of toned silver coins will conform to the standard progression.” In addition, a coin’s surface quality and finish can affect toning progression and patterns.

The final stage of toning or thin-film progression is called “terminal toning”. It is dull black in color, unattractive, and masks the details of the coin. It’s crucial to remember that a coin’s natural luster can’t be recreated or restored once lost. Luster is very important, but when dipped coins are preferred over naturally toned coins, the scale has tilted too far in the direction of luster and away from natural toning on early U.S. coins.

In Conclusion

Numismatists should learn to appreciate the fact that un-dipped coins are antiques that have survived their historic journey with their natural surfaces. Recognize and value coins with natural toning achieved over many decades rather than coins that have been intentionally tampered with to strip their surfaces clean in an often futile attempt to make them look like the day they were minted.

I recognize and value the fact that a coin is in the condition it is today because of the minting process used to make it, the period in which it was made, and whatever natural processes (aging, toning, oxidizing, etc.) occurred during its journey down the historic road it traveled. I appreciate nature’s beautiful and unique toning and do not feel the need to try and reverse the process to create the illusion that a coin was minted yesterday. Many numismatists embrace the following philosophy. Every time an original coin is improperly cleaned or conserved, it makes the ones that remain that much rarer and that much more valuable. I hope that you will join me and preserve the surfaces of these historic works of art rather than destroying nature’s work.

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Greg Shishmanian
Greg Shishmanian
Numismatics has been one of Greg’s passions since he was a young boy. He has studied the Liberty Seated Dollar series for over 30 years and his opinions are valued by many numismatists. Greg is a long-time member of the Liberty Seated Collectors Club (LSCC) and has published numismatic articles in the Gobrecht Journal, CoinWeek, Coin World, Numismatic News, and The Coin Dealer Newsletter. He strives to be a trusted source of information and provide honest advice and opinions.

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  1. Toning also helps with recognizing the age of the coin. It’s believability compared to a fake for example. Oxidation takes time. Compare a MS66 1921 HR Peace dollar with a 2021 MS70 Peace dollar.

  2. I remember a chemistry professor named Bill Masters. He sold coins at shows, and he truly was the ” master” of coin toning. The experts could not tell, and he had to show the knowledgeable coin scholars how he toned the coins. He had the know how, and the chemicals to create magnificent jobs of toning.


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