Toning: real, artificial, in between? -- periodic post

What follows is a distillation of many people's opinions and
observations, including my own. Additions and corrections are
welcomed. This document is copyrighted -- please don't republish
elsewhere. HMTL version available he http://rg.ancients.info/guide.

Toning: real, artificial, in between? -- periodic post

- - -
IN A NUTSHELL: Toning can add natural beauty, and value, to a coin. Or
it can be the result of tampering by a coin doctor. There are ways to
tell.
- - -

Among coin collectors, toning is almost as controversial as market
grading. Some like toning, some don't, some toning is real, some is
not.

As a general rule, toned coins tend to be preferred more by advanced
collectors than beginning collectors, while coins that look the same
way they looked when they came from the Mint tend to be preferred more
by newcomers. "People buy the color, experience, life of the coin, not
just the technical grade," says Bob Campbell, former ANA president and
coin dealer who sells toned coins. "Beginning collectors like blazing
white coins. More advanced collectors like beautifully toned coins."

There are exceptions to this, of course, with some advanced collectors
preferring their silver coins blast white. Both toned and untoned
coins have their attractions, though the attraction of a beautifully
toned coin is undeniable.

A beautifully toned coin is a coin that has aged well. The magnificent
aging of silver, in particular, is analogous to the magnificent aging
of deciduous leaves every year, in the right climates, before they
turn brown, the brilliant yellows and reds of the fall's foliage. This
doesn't always happen with either leaves or silver. You need the right
environment. When it does happen, it pleases the eye. Color is simply
more appealing than gray.

The appreciation of toning is often a sensibility that comes with
time, similar to appreciating the relatively small differences in
uncirculated grades, say between a 64 and a 66. When you first start
out, a coin with toning looks old or unnatural. Then you begin to
appreciate the sometimes marvelous ways that time can paint a
beautiful picture on coins.

Toning is just the numismatic way of saying tarnish. Ironically, like
rust on iron, toning on silver and bronze is a form of corrosion. What
happens with silver and bronze is similar to what happens with iron,
only it's a slower process with bronze and an even slower process with
silver. Like rust, the toning on coins gets thicker over time.

Not all toning is beautiful. With some coins toning can indeed be
brilliantly and spectacularly colorful. With other coins toning can
only subtly enhance eye appeal. With still other coins, toning can be
dark, streaky, splotchy, spotty, uneven, or otherwise ugly, making the
coin look like an algae-stained remnant from the Blue Lagoon. Because
such toning when extreme is considered environmental damage, the top
grading services won't grade these coins.

Toning is an alteration of the chemical makeup and color of a coin's
surface. It takes place naturally over time as the metal reacts with
chemicals in its environment, typically to various sulfur-based
compounds. Or it can be induced artificially, and more quickly.
Natural toning takes place more quickly in a warmer and more humid
environment.

Not all coins tone. If sealed in an air-tight environment, the
surfaces of a coin will deplete sulfur and other chemicals around it
and stop toning after that. Intercept Shield coin holders are designed
to intercept and neutralize sulfur and other contaminants and thus
prevent toning.

Metals

Numismatic metals tone in different ways. Silver coins as a whole tone
more beautifully than those made of other metals. Silver, exposed to
the right environmental influences -- to small amounts of hydrogen
sulfur in the air or larger amounts in albums, envelopes, canvass
bags, paper rolls, leather wallets or purses, rubber bands, and some
glues and paints -- can naturally turn subtle or sometimes brilliant
shades of yellow, magenta, turquoise, and other colors before
eventually turning black. The toning on silver is typically silver
sulfide.

Though toning on silver is most often caused by sulfur, the word
toning is sometimes used to describe other coloration on the surface
of a coin, even stains or dirt. Silver can react with other substances
such as chlorides in soil, producing silver chloride or "horn silver,"
which typically appears as an unattractive black, gray, purple, or
brown stain. The word oxidation is sometimes used in relation to
toning, though the word originally referred to a reaction with oxygen
and is probably still best used in this context.

The toning of silver coins is partly a factor of the other metals the
silver is alloyed with, particularly copper. Ninety percent silver
coins (most circulating U.S. coins) tone differently than sterling
silver (British coins), triple nine-fine silver (American Silver
Eagles), ancient silver coins, and most world silver coins. Silver
coins can turn green from the copper they're typically alloyed with,
the green resulting from copper carbonate or copper chloride.

Copper is the most chemically reactive numismatic metal used in the
U.S., and it and its alloys -- bronze and brass -- usually turn from
red to a dark and fairly unattractive brown. But copper can turn green
as well (called verdigris). Sometimes copper and its alloys can pick
up multiple subtle and attractive shades of red, brown, green, and
yellow.

Some lovers of early cents love the look of toned copper. "Old copper,
like beauty, appears to possess a certain intrinsic quality or charm
which for many people is irresistible," said Dr. William Sheldon in
his book Penny Whimsy. But the marketplace as a whole prefers red.
Early copper coins are more valuable if naturally red and untoned than
red-brown, which in turn are more valuable than brown.

Toning on copper and its alloys is often called patina, though all
toning is a type of patina, or coating. Brown or black patina on
copper is caused by copper oxide, cupric oxide, or cuprous oxide,
green by copper sulfate or copper sulfide, and greenish blue by copper
carbonate. "Bronze disease," which appears as a powdery green or
blue-green on ancient bronze coins and consists of cuprous chloride or
cupric chloride and hydrochloric acid, can eat away a coin's surface.

Gold, the least chemically reactive metal, generally stays the way it
is over even thousands of years, unless it's heated or exposed to sea
water. But the copper or silver that gold is typically alloyed with
can tone, turning the color an attractive deep orange or "orange
peal." Ancient gold coins, when unearthed, can be covered with
encrustations (dirt, grease, organic matter, salts, etc.) just like
other coins. Gold coins uncovered from ship wrecks can have minutely
pitted surfaces from the corrosive effects of salt water. Such coins
can look like cast counterfeits.

Some gold coins over time pick up subtle light brown or orange-brown
streaks or spots (called carbon spots or copper spots), which may have
been caused by incompletely mixed copper in the alloy, by airborne
contaminants, or by someone having breathed on the coin. Unless carbon
spots are particularly conspicuous and offputting, they doesn't affect
the value of gold coins. Toned gold coins with a "cloudy" affect are
usually artificially toned.

Nickel generally tones only slightly, typically becoming hazy gray
though sometimes light golden or pale blue. Nickel coins can also pick
up color as a result of PVC contamination. Wild rainbow toning on
nickel is usually artificial.

Aluminum (aluminium to the Brits and most of the rest of the world)
typically tones a dull, unattractive gray.

The color of the toning on any coin is a factor of how advanced and
thick the film of toning is. Early toning on silver coins is yellow,
with the colors progressing to magenta (purplish red) to cyan
(greenish blue) to black. The color results from "thin film
refraction" or "thin film interference," the refracting of different
wavelengths of light waves through the film. This is the same color
effect that appears with soap bubbles and when a thin layer of oil
lays on top of a puddle of water.

Different coins tone in different ways. Morgan dollars tone more
beautifully than Peace dollars because the planchets of the latter
were given a more concentrated acid bath at the Mint. Walking Liberty
half dollars tend to acquire unbalanced toning as a result of their
asymmetrical design. Many commemorative halves from the 1930s have
"tab toning" resulting from their original cardboard holders.

Many unattractively toned silver coins are "dipped" in a thiourea
solution, such as E-Z-Est Coin Cleaner, to remove the toning. If done
properly, a white dipped coin can be attractive. If overdipped, a
high-grade coin loses its luster and takes on an unattractive flat,
lifeless look. If a coin isn't rinsed properly after dipping, it can
pick up unattractive spotting or staining over time. Even properly
dipped coins don't tone the same way later as coins with original
surfaces, typically turning gray rather than colorful.

Artificial Toning

Because attractively toned silver coins are desirable to many
collectors, they usually carry a premium and sometimes a huge premium.
This is particularly true with coins that have "monster toning" (wild
toning), "target toning" or "bullet toning" (colors that change from
the coin's periphery in toward to the center), "rainbow toning"
(multiple colors), or "iridescent toning" (shimmering, with the color
pattern varying with the viewing angle). Such coins are even graded
higher by the grading services, which "market grade" according to a
coin's overall eye appeal.

This motivates some people to artificially tone, or doctor, coins.
Other times coin doctors artificially tone a coin to hide hairlines
from a prior cleaning, scratches, contact marks, or even repair work.

The difference between natural toning and artificial toning isn't
always clear-cut. Most toning results from human intervention (which
is one definition of "artificial"), from placing a coin in contact
with a man-made material such as a U.S. Mint canvass bag, an old Wayte
Raymond album, or a traditional felt-lined coin cabinet.

Most people, however, regard toning as artificial when there's a
deliberate attempt to impart it over a short time, such as baking a
coin in an oven (alone or in a potato), blasting it with a blow torch,
placing it in a covered bowl with crushed match heads (these coins
smell!), blowing cigarette or cigar smoke on it, thumbing it with nose
grease, or soaking or painting it with bleach, acid, or a
sulfur-containing chemical. The gray area involves deliberately toning
a coin with longer-acting techniques such as by setting it for several
months on a window sill in the sun, placing it on a block of oak wood
in the sun, wrapping it in tissue paper, or sealing it in an ordinary
high-sulfur envelope.

Coin collectors generally prefer modern coins to have natural,
untampered surfaces (collectors of ancient coins are much more
tolerant). The grading services do a good if not perfect job of
detecting artificial toning (AT), which is one of the reasons many
collectors buy older, higher-end coins in slabs.

Even so, some collectors are afraid of toned coins, says Mark
Salzberg, president of the coin-grading service NGC. "It simply
doesn't make any sense," he wrote in an article titled "The Virtues of
Toned Coins," which appears at the Web site Coin-Gallery Online. "It's
only natural that old coins, particularly silver pieces, acquire
various degrees and shades of color over time. This is one of the most
charming qualities of antique coins that distinguish them from more
recent issues, and I believe collectors who don't already do so should
learn to appreciate the virtues of toned coins."

To be fair, however, collectors have legitimate cause for being
concerned about some toned coins. Not even the top grading services
spot all artificially toned coins, says Bob Campbell.

In his video How to Tell Artificial Toning on Coins, available for
loan from the American Numismatic Association, Campbell says the
following are AT tip-offs:

* Circular toning spots resulting from the beading of the toning
liquid that was used.

* Colors that blend together out of sequence. With naturally toned
coins, the progression is yellow then magenta (pinkish red) then cyan
(blue-green).

* Toning that appears only on the tops of the lettering and devices
and not in the coin's recesses.

* Wild "circus" colors -- on 90 percent silver coins, for instance,
army green, bright pumpkin orange, and robin-egg blue.

According to PCGS's book Coin Grading and Counterfeit Detection, the
following are other indications of artificial toning:

* The toning floats on the surface of the coin rather than having
depth and being bonded to the metal.

* The toning occurs over hairlines or other marks.

* The toning exhibits bright "crayon" colors.

* The toning has a yellow-brown, smoky appearance, indicating it was
caused by cigarette or cigar smoke.

More on Toning

The Virtues of Toned Coins
http://www.coin-gallery.com/cgtoning.htm

eCoinPrices' Toned Coins
http://www.ecoinprices.com/toned.htm

Corrosion Doctors' Silver Artifacts
http://www.corrosion-doctors.org/Artifacts/silver.htm

Tonedcoins.com
http://www.tonedcoins.com

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