An 1856-O double eagle ($20 gold coin) is making the news. B&M, a division of Spectrum, will auction one on March 23 at the Baltimore Convention center. The ‘O’ stands for New Orleans, where it was minted. Is this date a Great Rarity? Before addressing the question, it makes sense to clarify the meaning of a ‘date’ and of a Great Rarity.

Bowers & Merena March 2007 Sale PCGS AU-53

The term ‘date’ refers to more than just the year on the coin. Two coins of the same type and year may have different dates. An 1817 half dollar and an 1817/4 half dollar are of the same year, but different dates. From the year 1906, there are four dates of dimes, 1906, 1906-O, 1906-D and 1906-S.
The term ‘date’ refers to a combination of the year, the characteristics of the digits, the details of the mintmark or lack of one, and the location of the Mint. Small dates, large dates, overdates, or even overmintmarks may indicate more than one date of the same type from the same year, and from the same Mint. Even a difference in the digits of a date, such as a fancy ‘2,’ may constitute an additional date relating to the same year. While the ‘year’ is part of the date, there is much more to the concept of the ‘date’ of a coin.

For U.S. coins, the absence of a mintmark usually indicates that the coin was struck at the main branch in Philadelphia. So, the Philadelphia location is often an implicit part of the ‘date’

New Orleans Mint double eagles struck from 1854 to 1861 are very rare. The 1856-O is the rarest.

The term ‘Great Rarity’ is often misused. For a coin to be a ‘Great Rarity,’ no more than twenty-five of the date (within the type) can be known to exist in the present, including both proofs and business strikes, and including all die varieties.

For some Great Rarities, more than twenty-five were known at an earlier time. The key point is the number that is known to exist in the present, not the number that may have existed at some other time. (more…)