patina

The green or brown surface film found on ancient copper and bronze coins, caused by oxidation over a long period of time.

pattern

An experimental or trial coin, generally of a new design, denomination, or metal.

pedigree

The record of previous owners of a rare or valuable coin.

piece of eight

Spanish or Spanish-American silver-dollar–sized coins used extensively in trade throughout the world during the seventeenth and eighteenth centuries. The forerunner of the American silver dollar.

piedfort

A pattern or regular design struck on a thick (often double-thickness) planchet.

pinhole

In the 19th century it was common practice to stitch several notes together for safekeeping, for hiding within a coat’s lining, or storing in a small pile. Today, when certain notes are held to the light, tiny pinholes can be seen.

Plain Back

A description of certain blue-seal Series of 1902 National Bank Notes without the dates 1902 and 1908 printed on the back (such notes have other motifs, however).

planchet

The blank piece of metal on which a coin design is stamped.

plate information (letters and numbers)

National Bank Notes: These were printed on plates with two or four subjects (and, from 1929 and later, six subjects). Although there are exceptions, generally the first note of a given denomination is given the plate letter A, the second note, B, and so on. Thus, if a plate had a $1-$1-$1-$2 arrangement, $1 notes would be printed with plate letters A, B, and C, sometimes with the same serial number, and other times with different serial numbers. In instances in which the same serial number was used (as in Original Series National Bank Notes), there would be three $1 notes with the same serial, differing only by plate letter A, B, or C, while the single $2 note would have the same serial as well, and plate letter A. Small-size National Bank Notes have a combination letter and number on the face, such as K124. Beginning with the Series of 1882, most (but not all) National Bank Notes bore a tiny number on the back plate. Other Notes: All federal notes from $1 to $10,000 bear a plate letter on the front. Small-size notes have a letter plus a number. Beginning in the late 19th century, back plates were given numbers. Numismatic notations: Plate information for a given note with just a plate letter on the face can be given as A, B, C, and so forth. For notes with back plate numbers, the notation can be “Plate information: A/20,” as an example. For a small-size note, an example is: “C73/278.”

plate information (serial numbers)

On all federal notes $1 to $10,000, a Treasury Department serial number is printed once or twice on the face. On early notes this can be a number or a number in combination with one or more letters. For small-size notes, a combination of numbers and letters is used. The same serial numbers were used on different series and varieties of notes in the same era. Accordingly, the numbering system of Series of 1886 $5 Silver Certificates was independent of numbers used on Gold Certificates or National Bank Notes, and so on. National Bank Notes: On a 19th-century large-size National Bank Note, one of two numbers printed on the note is the Treasury Department serial. The other (usually lower and often in the range from 1 to 10,000) is the number in a sequence for the specific bank and denomination of a given bank-note type. An example is provided by a $10 Series of 1902, Date Back note from the First National Bank of West Derry (NH). Records show that these bills were issued with serial numbers 1 to 1570 on plates arranged $10-$10-$10-$20, meaning that each plate had three $10 notes with the same serial plus one $20 note. The total number of $10 bills made was 4,710 (three times 1,570). Today, a bill in a private collection bears plate information E/74, bank serial number 275, and Treasury Department serial number H765723.

plugged coin

A holed coin that has been repaired with a plug, usually of the same metal or a similar-appearing metal, in an attempt to increase its numismatic value.

Poker Chip Note

Nickname for the Series of 1923 $10 Legal Tender Note. The 10 denomination, given twice on the back, is surrounded with a round frame.

porous

Rough; descriptive of a coin’s surface that has been exposed to oxidizing elements.

Porthole Note

Numismatic nickname for the $5 Series of 1923 Silver Certificate with the portrait of Abraham Lincoln in a heavy frame fancifully resembling a ship’s porthole.

Postage Currency

Federal fractional bills made in denominations of 5¢, 10¢, 25¢, and 50¢, and first issued in August 1862 to help alleviate a coin shortage. These were followed by Fractional Currency notes.

Premium Quality (PQ)

Premium quality. A “gem” coin.

prestrike

A coin struck in a year prior to that the date that appears on the piece

privy mark

Letter(s) or symbol struck on a coin in place of, or in conjunction with, a mintmark.

proof coin

A coin struck for collectors by the Mint using specially polished dies and planchets, and multiple blows under higher-than-normal pressure.

proof finish

A coin finish in which devices are rendered in frosted relief on a mirror field.

proof note

A proof (not capitalized in usage) note is an impression for test or other purposes, from a complete or partially complete plate, to illustrate its appearance. Such notes usually bear no serial numbers, or else just zeroes, and may be missing other elements, such as the Treasury seal and signatures. Proof notes are usually printed on only one side, and show either the front or back, but not both. Such proof notes are highly prized today. Synonym: Specimen note (usually capitalized as such). Specimen Fractional Currency notes, denominations 3¢ to 50¢, are sometimes called proof notes.

Proof set

A special packaged set created for collectors with some/all of the proof coins made during a given year.

Proofs

Coins struck for collectors using specially polished dies and planchets.

provincial cent

The bronze one-cent coin issued by the Province of Canada in 1858 and 1859.

punch

A steel tool, with its image in relief, used to strike all or part of a coin’s design, letters, or numerals into a working die.

PVC

Polyvinyl chloride plastic. Not recommended for numismatic storage, because of potentially damaging chemical interaction.