What is a Proof Coin?
The U.S. Mint defines the proof strike type as “a specially produced coin made from highly polished planchets and dies and often struck more than once to accent the design. Proof coins receive the highest quality strike possible and can be distinguished by their sharpness of detail and brilliant, mirror-like surface.”
The raised parts on a coin are called the “devices,” while the flat area is called the “field.” In a proof coin, the field is mirrored while the devices are frosted. Historically, proof coinage came in matte-proof, satin-proof, and brilliant-proof, while most of the proof coinage today is brilliant proof with frosted devices.
Proof Finish- The Collector’s Finish
Proof coins rarely enter circulation and are not generally intended for use in daily transactions, even if they carry a face value.
Sometimes proof coinage provides collectors with a special strike of another issue, usually a business strike, which occurs on coinage intended for circulation. Collectors can observe an example of this phenomenon in the United States Mint’s American Silver Eagle series, which is regularly issued in both a bullion Uncirculated finish and in a collectors Proof finish.
Proof coinage tends to be more expensive to purchase because of the extra time, effort, labor, and production costs often required to make the coins. Usually, proof coinage will carry a limited mintage, especially when compared to their mint state counterparts.
In 2018, the United States Mint issued a vast 15,700,000 bullion Uncirculated American Silver Eagles. During this particular year, the U.S. Mint issued two Proof Silver Eagles, one from the San Francisco Mint with a mintage of just 158,791, and the other from the West Point Mint with a mintage of 361,192. Both 2018 Proof Silver Eagle mintages were far lower than their mint state counterparts.
How Are Proof Coins Struck?
Proof coins are struck using specially manufactured selected polished dies to give the signature “mirror effect” associated with proof coins. Most Proof coins are struck at least two times, if not more.
Cameo Contrast in Proof Coins
The term Cameo refers to the amount of contrast between the raised design (or relief) and the background of the coin (or field). This effect is achieved when the planchets are polished to remove any imperfections before being struck.
Grading Companies like Numismatic Guaranty Corporation (NGC) will even designate coins Cameo or Ultra Cameo (UC). The cameo designation is awarded to coins that display moderate contrast, while coins awarded the Ultra Cameo designation show bold contrast between the relief and field.