What makes a coin rainbow toned

All methods of artificially inducing toning are condemned by serious coin collectors, and artificially toned coins are considered "problem" coins, just as if they were damaged, cleaned, or polished.

A coin that has been artificially toned loses its collectible value, and will generally sell for only the bullion value of the metal. Third-party coin grading services refuse to assign artificially toned coins a specific numeric grade, instead grading them as " details " i. In order to identify an unslabbed or "raw" coin as artificially toned, it's important to understand the toning characteristics of the coin's metal - copper coins tone differently than silver coins, and silver coins differently than gold coins.

Of the metals most often used to produce coins, copper is the most chemically reactive and therefore the most prone to toning. When first minted, copper coins have a bright red color. Over time, the copper oxidizes and the coin's color darkens to brown. How long that process is up for discussion, but most 19th century coins and many 20th century coins have now toned to a brown color. Copper can also acquire "rainbow" multicolored toning, but it is much less likely.

Second only to copper in terms of toning potential is silver. Like copper, silver usually oxidizes over time towards a grey color. Silver frequently reacts with sulfur to form rainbow toning - the Morgan dollars at the top of the article are examples of that process.

Nickel coins are less prone to toning than either copper or silver. Nickel by itself is a fairly unreactive metal, and generally only oxidizes to a deeper grey color over time. But when alloyed with copper, as with most modern U. Toning is a slow and normal process that can take months to years to appear. Should you worry about toning? Even in worst cases, the tone color will normally take centuries to reach its very darkest and usually its least attractive appearance.

Tarnish and toning are pretty much synonymous on the scientific scale. There are several factors in determining the value of a coin, but at the very top for most people is its appeal. But again, beauty is in the eye of the beholder. If coin collecting was all about shiny coins, collectors would have much less resistance when it came to buying cleaned coins.

Historically, beautifully toned coins that are older garner a premium. A shiny coin is a shiny coin. Older coins can show more color variations due to multiple and less pure metal "blends". And metals like copper and silver can react more quickly and often times tone easier when exposed to the environment. Unfortunately, just as toning happens naturally with coins, it can also be mimicked artificially by "coin doctors". Think of coin doctors as forgers. Why would anyone try to artificially tone a coin?

It usually takes some experience to recognize a coin has been artificially altered. The last thing you want is to pay for what you think is a gorgeous coin only to later find out it was doctored, making it worth little. I have a Georgia quarter with obverse having a swirl of light black.

It seems as though it is mixed with the metal. On the reverse it is a darker black over the whole area. Do you think this is discoloration or possibly an error? I have two american eagle silver dollars accompanied by a certificate of authenticity.

I received them in mint condition but then after three months, they have both tarnished with a distinctive tarnish line running across of both faces of each coin. Both issued by the New York Mint. Will they replace these? I use to be a pipe fabricator. If you are asking a question or making a statement your wrong. Not all metals corrode. Grade of the metal makes a big difference like stainless steel can be touched and set out in the air for a long long time and still … Read more ».

I work in power plants an Hrst boilers after one start up the stainless will be black an rusted sometime all stainless really is is corrosion.

AU is almost uncirculated.. The oils in our finger cause the loss of lustre and a coin goes from grades of perfect to almost. I have a nickel that is multi colored. Heritage Auction Galleries. Toned coins are the result of a chemical process that reacts with the surface metal of a coin.

Although any coin can tone, silver and copper coins are most susceptible to the toning process. United States Gold coins , on the other hand, are the least susceptible. However, these gold coins can still take on subtle shades of toning as they get older.

It is the small amount of copper that can oxidize and result in the toning of the coin. The amount and variety of toning can vary widely. Coin doctors have studied the chemical process of toning very carefully. In fact, some of them are so good at artificially toning a coin they can reproduce toning that naturally takes a hundred years in a matter of minutes. Therefore, before you pay a large sum of money for beautifully toned coins, have it authenticated by a professional to ensure that the toning is natural and original.

Toning occurs naturally over time. The toning process can be accelerated by heat, moisture and a variety of chemicals in the environment. Some of the most harmful chemicals to coins can be found in cheap coin holders and coin folders. Silver coins tend to tone in the most vivid colors. Colors can range in a variety of hues from brilliant blue to deep magenta, from vivid red to deep orange and a variety of shades of olive, green and gold. Additionally, toning can also turn ugly and occur in shades of black and brown.

In this case, the answer can be mainly attributed to a quality that has fascinated countless coin collectors for years: beautiful rainbow toning. Bid or buy US coins for sale, value your item, or request a free appraisal to sell your collection. When trace amounts of sulfur or other chemicals come in contact with the surfaces of a silver coin over a period of years, the color and appearance of its surfaces will begin to slowly change.

For example, the paper envelopes and canvas bags that were once used to store coins have often resulted in lovely toning after years of storage, especially in warm or slightly damp environments. When left to its own devices no pun intended , the thin layer of sulfide that forms over the surfaces of a coin may range from a pale blush of color to lovely and vibrant hues.

It is this type of toning, a true happy accident, that many numismatic connoisseurs covet and seek out for their collections. Not all toning is coveted, however. Such heavy toning is not as commonly sought out by collectors as the more vibrant hues and is not always considered to be desirable.