Toning occurs naturally over time. It is mostly the result of oxygen and/or sulfur reacting with the coin’s metal. The toning process can be accelerated by heat, moisture and a variety of chemicals in the environment. Silver coins tend to tone in the most vivid colors.
How do you tell if a coin has been artificially toned?
Signs that a Coin Has Been Artificially Toned
- Hairline scratches on the coin’s surface can indicate cleaning with an abrasive chemical or brush.
- A dark brown or bluish hue often comes from chemical toning.
- Spots often appear on an artificially toned coin’s surface if the chemical reacts unevenly.
Why are some coins yellow?
A gold tone, particularly if only one side is effected is usually caused by the sun having a reaction to the metal and whatever elements are on that surface facing the sun. This is what is called “environmental damage”, it is not an error and adds no premium value to a coin.
What causes rainbow toning on coins?
“Rainbow” toning or patina is an optical effect caused by graduated layers of silver oxide on the surface of a coin. This is often seen on coins that have been in contact with a sulfur source (a great oxidizer) for a good number of years (usually 20 years or more).
Does toning increase coin value?
Different colors and patterns of toning can have varying effects on a coin’s grade and value. For example, brown spotty toning could decrease a coin’s value, while colorful rainbow toning could increase it. Toning patterns may cover an entire coin, just one side, or just one area.
What do you need to know about Proof coinage?
Proof coinage. Proof coinage refers to special early samples of a coin issue, historically made for checking the dies and for archival purposes, but nowadays often struck in greater numbers specially for coin collectors (numismatists). Nearly all countries have issued proof coinage.
Why did the US stop making proof coins?
The United States Mint temporarily stopped proof coinage during World War One to prevent wasted metal. By the 1930s, the Depression caused a lot of the big changes to U.S. currency: economic hardship forced the government to remove gold coins from circulation while also creating “bank holidays” to prevent a run on cash.
Is there a difference between uncirculated and proof coins?
U.S. commemorative and bullion platinum, palladium, gold, and silver coins are also often issued in both uncirculated and proof types, sometimes with different mint marks . Starting in 1947 the U.S. mint began producing “mint sets”, and because of the terms used there is some confusion over the difference between these and proof sets.
How are proof coins struck under higher pressure?
Most proof coins are double struck under higher pressure. This does not normally result in doubling that is readily observable, but does result in the devices being struck fully. After being struck, they are separately and individually handled, in contrast to normal coins which are thrown into bins.
