Proof Coins

Historically, a “proof” coin was essentially a sample, a test piece that was created in order to check the dies and to ensure that the coin looked as it should. These coins were struck in very small numbers and are incredibly rare today. In the modern age, proof coins are created for investors. They are often produced in higher numbers, but those numbers are still kept to a minimum in order to increase the rarity and therefore the value of these coins.

Modern proof coins also tend to be struck to a very high standard, with a stronger strike, a greater luster and more eye appeal.

Who Strikes Proof Coins?

Most official mints create proof coins, and many private mints also produce coins that fit this classification. Even at the biggest mints, the standards are always high when proof coins are concerned. At the Royal Mint, which is the oldest mint in the world, the dies that strike proof coins are still finished by hand, which ensures that imperfections are reduced and that they are noticed immediately when they appear. The blanks are placed into the press by hand, before being struck as many as 6 times.

The care and attention that the Royal Mint gives these coins is characteristic of all mints, and goes to show that even the biggest mint in the world still adheres to strict quality control procedures where proof coins are concerned.

All individual mints have their own way of doing things, but when it comes to proof coins, they are usually just as strict, adopting many of the following methods:

  •         Hand-Finished Dies: The dies that strike these coins are finished by hand, with special care and attention paid to ensure that they are perfect. Chemicals may also be added to impart some extra luster onto the coin.
  •         Cleaned: The dies are air-cleaned after each striking, removing any debris that may result in an imperfection.
  •         Re-Polish: Circulated coins and even bullion coins use dies that have struck tens of thousands of coins, but the dies used to strike proofs are often re-polished, re-worked or changed completely after just a few hundred strikes.
  •         Strike Rate: Bullion coins are produced at a rate of about 3,000 an hour. But because proof coins require a little more care, it is not unusual for mints to produce just 40 to 60 of these an hour.

How To Spot A Proof Coin

Proof coins are unique, with a greater luster, greater detail and better eye appeal than many other coins. This is especially the case with modern proofs, where advancements in minting technology has made the process of creating proofs easier, while also improving the product itself.

Proofs are often struck with dies that have been acid treated, which gives the coin a frosted look on the raised parts of the design. The background should have a highly reflective finish, creating a stunning contrast between the raised and frosted design. This contrast is known as a “cameo”, and a stronger contrast is referred to as a “deep cameo”. In many cases, the initials “CAM” and “DCAM” are used to describe these two finishes.

The detail of proof coins is also far greater than standard coins, which stems from the fact that these coins are struck several times, allowing the die to penetrate deeper and to leave a greater impression. With this in mind, designers often create complex and intricately designed dies, knowing that every line, every feature and every mark will show exactly how they want it to show.

How Are Proof Coins Graded?

You will often see the initials “PR” or “PF” used to denote a proof, followed by the grade of the coin. As with uncirculated and circulated coins, the grading for proof coins is based on something known as the Sheldon Coin Grading Scale. This scale does not cover proof coins, but it has a scale of its own for that, with the uncirculated grades mirroring those in the standard scale.

As an example, an uncirculated coin with the grading “MS-67” should have a sharp strike, full luster, 1 or 2 barely visible scuff-marks and 1 or 2 hairlines that are only visible under 6x magnification. And a proof coin that is graded as “PR-67”, must adhere to the same specifications.

In the standard scale, uncirculated coins (those that show no signs of wear) are numbered 60 through to 70, ranging from a coin with many visible flaws and poor eye appeal, to one that is flawless. All grades below 60 are for circulated coins, ranging from those classed as “poor”, to those classed as “almost uncirculated”. In the proof scale, numbers 1 through to 59 are for coins graded as “impaired proofs”, which includes coins that show signs of circulation (heavy wear) and coins that have been handled poorly.