The same date and design can exist in several different finishes, each made differently and valued differently. Here is what the terms mean.
Business strikes (circulation strikes)
Ordinary coins made for everyday use, struck once at high speed on regular planchets and shipped in bags. "Uncirculated" simply means a business strike that has never been spent, so it shows no wear.
Proof coins
Proofs are made specially for collectors using polished dies and specially prepared planchets and each coin is struck more than once at lower speed. The result is a sharp strike with mirror-like fields. Most modern proofs also have frosted designs, creating "cameo" contrast. Proofs are sold in sets and handled individually, so most survive in near-perfect condition. Since 1968 most US proofs have been struck in San Francisco and carry an S mint mark.
Mint set coins and other finishes
- Uncirculated (mint) sets contain business-strike coins packaged for collectors.
- Special Mint Sets (SMS) were made from 1965 to 1967 in place of proof sets, with a satin-like finish and no mint marks.
- Satin finish coins were included in mint sets from 2005 to 2010.
- Enhanced uncirculated coins combine frosted and brilliant areas using laser-treated dies.
- Reverse proofs invert the usual look: frosted fields and mirror-like designs.
- Silver proofs of modern dimes, quarters and halves were struck in 90% silver from 1992 to 2018 and in 99.9% silver from 2019.
How to tell a proof from a business strike
Tilt the coin under a light. A proof's fields reflect like a mirror and its rims are sharp and squared; a business strike has a satiny, cartwheel luster and softer details. Modern proofs almost always come in sealed government packaging or slabs. A proof found loose in change is unusual.
On each WePlayCoins coin page, the "strike type" row tells you which kind of coin you are looking at and proofs and collector issues are listed separately from circulation strikes.
A short history of US proof coins
The Mint struck proof coins as special presentation pieces from the early 1800s, but it began offering them to the public in quantity in 1858. Proof sets were made almost every year until 1916, then stopped. They resumed from 1936 to 1942, paused again during the Second World War and returned in 1950. From 1965 to 1967 Special Mint Sets took their place. Proof sets have been made every year since 1968.
Early twentieth-century proofs did not always have mirror fields. Lincoln cents from 1909 to 1916 and Buffalo nickels from 1913 to 1916 were struck as matte proofs, with a fine granular surface. Gold coins of the same period were also made with matte or sandblast finishes.
The history of mint sets
Uncirculated mint sets were first sold in 1947. Until 1958 each set contained two examples of every coin, so both sides of each coin could be displayed in the cardboard holder. That cardboard tones coins, which is why many early mint set coins have colorful toning on one side. No regular mint sets were made in 1982 and 1983, when the Mint offered souvenir sets instead. Special Mint Sets replaced them from 1965 to 1967.
Burnished, prooflike and first strikes
Several more terms describe finishes between a business strike and a proof. Burnished uncirculated coins, made mainly at West Point from 2006 as collector versions of bullion coins such as the American Eagle, are struck on burnished blanks and carry a W mint mark. Prooflike and Deep Mirror Prooflike are business strikes, mostly Morgan dollars, that came from freshly polished dies and show mirror fields. They are not proofs, because they were struck once at normal speed. First strike and early release are marketing labels used by grading services for coins received within a set period after release. They describe timing, not a different finish.
Caring for proofs
A proof's mirror surface shows every flaw. Fingerprints etch into the fields within weeks and the lightest wipe leaves fine hairlines that lower the grade. Keep proofs in their original lenses or in sealed capsules and handle them only by the edge. Silver proofs can also develop small white milk spots over time. Store them cool and dry and do not attempt to remove spots or haze yourself.
How proofs are graded
Proofs use the same 1 to 70 scale, with PR or PF in front of the number. Because they are handled carefully, most modern proofs grade PR-67 or higher. Contrast designations matter as much as the number: Cameo coins show frosted designs against mirror fields and Deep Cameo or Ultra Cameo coins show the strongest contrast. Older proofs with hairlines from cleaning or handling may grade in the low 60s or below. An impaired proof is one that has seen wear or damage.
Brilliant uncirculated and other trade terms
Brilliant Uncirculated, often shortened to BU, is a trade term for business-strike coins with full original luster. It is not an official grade and coins sold as BU can range from MS-60 to MS-65 or higher. Original bank-wrapped rolls, called OBW rolls, contain uncirculated coins straight from the Mint's distribution. They are popular with collectors looking for high-grade coins of a modern date.
Frequently asked questions
Can you spend proof coins?
Yes. Proof coins are legal tender at face value, but spending one wastes its collector premium and its original packaging.
What does BU mean on a coin?
BU stands for Brilliant Uncirculated, a trade term for a business-strike coin with full original luster. It is not an official grade.
Is a prooflike Morgan dollar a proof?
No. A prooflike coin is a business strike with mirror fields from freshly polished dies, struck once at normal speed.