An infrequently encountered or available item - The number of known surviving specimens of a particular issue, as may be indicated by a rarity scale index
generally relates to the infrequency or relative unavailability of a coin, as a direct function of important factors such as the original mintage and overall survival rate.
The number of specimens extant of any particular numismatic item. This can be the total number of extant specimens or the number of examples in a particular grade and higher. (This is referred to as condition rarity.)