Beautiful rainbow-toned coins command a premium. But coin “doctors” who artificially tone coins have made collecting and certification a challenge.

There are people the world over who will pay top dollar for dazzling color in jewelry, a painting, a car, an article of clothing — and, yes, even a coin. Price does not seem to matter if the color excites and moves the buyer. The emotions take over.

With the right splashes of rainbow color, no price is too high for a $30.00 coin. The rich, colorful toning is what matters. It is love at first sight. Even in today’s economy.

Colorful toning on coins, however, will always be a topic fraught with controversy. Research chemist and numismatist Weimar W. White tells us without hesitation that natural toning is a progressive form of damage to the surface of a coin.

Claims of damage to coins

White writes that coin collectors have a “difficult time with the concept that hydro sulfuric acid can remove atomic-state atoms from the surface of their prized specimens. This is because the oxidized silver atoms are still on the surface in the form of silver sulfide that can give diverse colors.” The chemist-numismatist informs us that the film of silver sulfide is bonded to the coin. This film can be removed with a thiourea dip, which “will result in a measurable weight loss to the coin.”

Nonetheless there are collectors and dealers who enjoy collecting beautifully toned coins. Morgan dollars with beautiful colors “are one of the most diverse and collectible areas in numismatics.” Collectors of such coins consider them to be unique works of art. But how did so many silver dollars end up so beautiful?

Beautiful rainbow-toned Morgan dollars

Storage in canvas U.S. Mint bags is one way. Sulfur was used as a preservative in the bags and reacted with the silver oxide patina on coins to bring out bright iridescent colors. The sulfur can give the coins a burnt yet colorful appearance. Variables in the Mint bag toning process are humidity, length of time stored, heat and cold, moisture, and the location of the coins in the bag. Constant contact with the canvas is needed for the coins to tone. Mint bag colors include bright red, magenta, emerald green and electric blue. An arc of rainbow coloration forms if a coin rests partially atop another coin. Textile patterns can also be the result of Mint bag toning. Color patterns can be quite diverse but are only found on one side of the coin.

Another method that results in dramatic toning is long-term storage in paper coin envelopes. The sulfur in the paper helps create iridescent toning. This often results in two-sided coloration. Bright peripheral toning in concentric rings of color are associated with storage in a coin album. Colors found on these coins are generally pastel shades of violet, sky blue, sea-green, lavender and light yellow.

“…a coin can be simply breathtaking”
Mark Salzburg, the CEO of Numismatic Guarantee Corporation (NGC), writes that, “the most desirable toning is that which appears in concentric circles of distinctive colors …. In many instances the beauty of such atmospheric action on a coin can be simply breathtaking.” Salzburg also confronts a predisposition of collectors to favor “white” coins: “It’s only natural that old coins acquire various degrees and shades of color over time. This is one of the most charming qualities of antique coins.”

Another aspect to consider is that beautifully toned coins command a premium in the marketplace. And prices continue to rise on these beauties. Some collectors shy away from toned coins because they are afraid of buying coins with artificial toning (AT).

Beautifully toned coins carry a premium – sometimes a “monster” of a premium. This has given rise to a cottage industry: coin “doctors.” These people artificially tone (or “doctor”) coins. Sometimes coins are “doctored” to hide hairlines, scratches or damage. It can be easy to spot an AT coin; sometimes, however, it is quite difficult.

Confessions of a coin “doctor”

The story of how a coin gets doctored begins with a lie … with the explanation that a group of coins which had “toned” considerably was from an old time collection. They had apparently been stored in paper envelopes or the old style coin albums. The coins in question exhibited beautiful shades of purple, orange, sea green and light tinges of orange. These were blended in color hues that produced streaks and cameo target designs on several of the coins.

The lie was quite believable and the wrinkled cellophane with names of the major auction houses and old time collectors made it seem more real than real. The coins are then paid for and locked away. Some months later a dealer (himself a coin doctor) visit’s the proud new owner. He inspects the coins and finds his own handiwork among them. A discussion about chemically treated coins begins. The doctor admits working on some of the coins in front of him, as well as an intimate knowledge of the coin doctoring process. And so began the education of the dealer.

“Coins that exhibit spotted toning – no matter the colors – are most likely artificially produced,” the doctor explains. The spots are mistakes that cannot be removed. The chemicals used to “tone” coins are mixed in crucibles and heated with a small Bunsen burner, which keeps the “mixture thinned and homogeneous.” Q-Tips, swabs or gauze are used to “paint” the coin with chemicals. Then light heat is used “to give the appearance of age.”

How can someone interested in collecting and investing in coins that are toned do so successfully without getting burned? One way is to only buy toned coins in certified holders (called “slabs”) from Professional Coin Grading Service (PCGS) or NGC; these two companies are considered the top two in reputation and market value.

The bottom line is that a collector of toned coins needs to arm himself with knowledge. Read everything you can on the subject. Look at tons of coins. Talk to people at coin shows and your local coin club who have experience buying and selling toned coins. The more knowledge you have, the more of your money you will keep!