Key date

A key date is a term used in coin collecting and it refers to a date (or date and mint mark combination) of a given coin series or coin set that is harder to obtain than other dates in the series. A key date coin is usually one with a lower mintage total and it is more valuable than others in the series. Many coin collectors collect coins to fill out a complete set of a series.

There are also semi-key dates in coin collecting. A semi-key date coin is typically one that is not as rare as the key date. The semi-key date often sells for a premium over common date coins, but less than the cost of a key date coin.

A key date is the term for a coin which is scarcer and harder to obtain in a series.^[1][2][3] Often coins with certain years or Mint marks are key date coins.^[4][5] Some factors that influence whether a coin is a key date include: demand, quantity of coins struck, the population of surviving examples and rarity of mint sate examples. The cost of the key date coins in a series are usually the most expensive to obtain.^[6] The coins are also often referred to as the rarest in a series.^[3]

Key dates are an important component of coin collecting because many collectors collect coins which fill a coin set: key date coins are the most important. They are valued by collectors because they are needed to complete coin sets.^[7]

For the United States collectors of the Lincoln cent series, the 1909-S VDB Lincoln Cent is the rarest and most expensive of cents.^[8] The 1909-S VDB Lincoln cent is considered to be a key date due to its low mintage of only 484,000.^[9]

The United States 1893-S Morgan dollar is known as the key date in the Morgan series.^[10] The 1893-S Morgan dollars were struck at the United States San Francisco Mint. Only 100,000 coins were struck making it the lowest mintage of any business strike Morgan Dollar.^[11]

The next level of difficult to obtain coins in series are often referred to as semi-key dates or simply semi-keys.^[12] The semi-key date coins are scarce and sell for a premium but they are not as scarce and rare as a key date.^[6][13] There are not rules which determine which coins are semi-key dates. Some coin collectors the coins in the series with lower mintage figures to be semi-key dates.^[6]

Numismatic Guaranty Company (NGC) produced a list of counterfeited coins: many of them are key date coins. One of the most common methods of counterfeiting involves adding a mintmark to the coin, in order to turn it into a key date coin.^[14]

• Pasek, Matthew (2017). US Key date coin hand-e-book 1892-present. Independently Published. ISBN 978-1549547751.

• Key Date Coin Guides
• More Key Date Coin Guides