What Is a Proof Coin?

What Is a Proof Coin?

By: Sean McConeghy

History of Proof Coins

While coins have been struck for over two and a half millennia, the modern hobby of coin collecting dates back to the 1300s. The undertaking was considered akin to art collecting, and it became known as “the hobby of kings.” For about three centuries, many wealthy individuals collected coins mainly for their beauty. Almost 300 years later, the collection and categorization of coins became more of an academic discipline. As knowledge and the sharing of knowledge grew, the hobby extended beyond the upper class to the middle class. By the19th century, the pursuit expanded to include foreign currencies as well as historic coins. Today, coin collecting is more democratized than ever, and numismatics is both a field of study and an industry unto itself.

Proof coins date back to the early days of the United States and can be credited to Adam Eckfeldt. Eckfeldt was a machinist and die maker who worked for the U.S. Mint. He took special care to prepare dies and select polished planchets to ensure the highest quality of the first type of each coin. These coins were of exceptional quality and were typically kept by collectors. The coins were also given to politicians and special visitors to the mints. While they were not yet known as “proofs,” these were the first proofs.

The U.S. Mint started striking proofs as such in or around 1817. The mint decided to meet collector demand by offering these coins for sale clearly distinguished from standard-issue coinage. In 1861, the mint started to provide sets of proofs to collectors. The sets were not comprehensive for all U.S. coinage, but they were comprehensive by category. As such, the answer to “What is a proof set?” has changed over time. At the time, proof sets would have included things like all silver coinage, all gold coinage, or all minor coinage. Today, the U.S. Mint’s Proof Sets include examples of each coin released for circulation.

Today, proof coins are some of the most popular choices among collectors. Some coins are struck only as proofs, while in other cases, proofs are issued along with bullion counterparts. The American Silver Eagle, American Gold Eagle, and American Platinum Eagle have proof versions that are extremely popular among collectors.

What Is a Proof Coin?

Broadly speaking, the United States Mint produces four types of coinage: bullion, circulated, uncirculated, and proof. Bullion coins are struck from precious metals for collectors. Their value is tied to that of the metal. Uncirculated or Burnished coins are hand loaded into the press and struck on burnished blanks, ultimately resulting in a soft, matte-like finish. They generally come with certificates of authenticity. Circulating coins are struck for daily commerce. These are coins like pennies and quarters. Proofs coins are considered the finest quality of coin produced by the U.S. Mint. To achieve this finish, specially treated, hand-polished, and clean dies are struck at least twice with heavily polished dies. These coins also traditionally come with certificates of authenticity and are encased in protective capsules.


So, what is a proof coin, and why are they worth collecting? Because of the treatment of the dies and polishing of both the dies and the planchets, proofs have what is called a “cameo” effect. Cameo means that their devices – the raised or incuse designs – are frosted while their fields – the negative space is highly reflective. This visually appealing, high contrast effect is measured by grading companies. The most common terms used for this are “Deep Cameo” (PCGS) and “Ultra Cameo” (NGC). These terms mean that there is an especially sharp contrast between frosted devices and mirrored fields. In both cases, the frosting must be complete and unbroken. 

What Is a Proof Coin Set?

The United States Mint issues sets of proof coins for collectors every year. The U.S. Mint Proof Set includes proof versions of each of the coins struck for circulation. (3) The coins in this set are struck from the same metals as circulated coinage. The mint also annually issues Silver Proof Sets. While the penny, nickel, and dollar coins in these sets are struck from base metals, the dime, half dollar, and quarters are each struck from .999 fine silver. Gold Eagle Proof Sets featuring one of each size of the coin are also available annually.

In 2021, the Proof Set includes just seven coins, down from ten in previous years. The penny, nickel, dime, half dollar, and dollar are standard, while it also includes the last issue of the America the Beautiful Quarters series, which honors the Tuskegee Airmen, and a General George Washington Crossing the Delaware Quarter. The dollar coin commemorates the service of Native Americans in the military, thus completing a trifecta of appeal to collectors who honor the service and history of the American armed forces.

How to Differentiate a Proof Coin from Other Coins

Proof coins can be differentiated from other types of finishes due to their mirror or cameo effect. The first proofs were created through specially prepared dies even before the term “proof” was used. Although the U.S. Mint struck proofs as such starting in the 1800s, only the first 30-50 proof coins struck would display deep cameo contrast. It wasn’t until the 1970’s that the technology was developed to create that level of contrast on all strikes.

Most proofs are struck at least twice, with some even being struck more times. The planchets have been polished heavily to ensure that they are free of any imperfections before they are struck.

Grading companies grade proofs on the Sheldon Scale, the same one used for business strikes. Coins are graded as Proofs rather than Mint State, with Professional Coin Grading Service (PCGS) using “PR” and Numismatic Guaranty Corporation (NGC) using “PF.” There are eleven grades for proofs ranging from 60 to 70. PF/PR70 coins appear perfect under 5x magnification and have complete mirror surfaces. PF/PR65 pieces, also known as “GEM Proof,” have high-quality mirror surfaces but a few noticeable hairline scratches. Strikes may be average to weak. The lowest grade, PF/PR60, indicates that a coin has a weak to average strike and has few if any, mirror characteristics.

The grading companies also grade the cameo effect. “Brilliant Proof” means that a coin has large patches of brilliance on the devices or entire surface. “Cameo” means that a piece has light to moderate frosting. “Deep Cameo” or “Ultra Cameo” indicates that a proof’s frosting is strong and unbroken and contrasts sharply with deeply mirrored fields.

What Is a Reverse Proof Coin?

Although proofs make up the lion’s share of collectible coins, reverse proofs are also popular. The United States Mint struck its first ever reverse proofs, a Gold Eagle and a Silver Eagle, in 2006 to mark the 20th anniversary of those programs. As the name suggests, a “reverse proof” is a proof in which the devices are mirrored, and the fields are frosted.



In addition to reverse proofs, there are also “enhanced reverse proofs.” The distinction between the two is that enhanced reverse proofs have different design finishes and multiple polishes. These variances make for more visually impactful designs.

Proof versus Reverse Proof finishProof versus Reverse Proof finish

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