This is the opening part of a feature story on finishes used on U.S. coins that first appeared in the June 6, 2016, Monthly issue of Coin World:
What’s in a coin’s finish?
Apparently quite a lot, considering the effect on value for some coins struck by the United States Mint.
The Mint’s extensive experimentation over the past decade with coin finishes — sometimes using multiple finishes on one or both sides of the same coin — has factored into some individual coins’ appreciation in value (or lack thereof).
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Most special finishes are employed on limited-edition numismatic products, but some larger canvas releases like gold, silver and platinum American Eagles and commemorative silver dollars are subjects of special finishes also.
The special finish experiments have not been restricted to just one production facility. Special finish products have been struck at all four Mints.
As experiments progress with technology advances and are implemented, the U.S. Mint’s production development specialists at the Philadelphia Mint have tinkered with the bureau’s ability to execute multiple finishes on the same coin
Some collectors may think coins have just two finishes — Proof, in the modern sense, with frosted devices contrasted against mirrored fields, and the business or circulation strikes mass-produced for use in commerce.