Last week Bill Eckberg asked:

Brad Karoleff writes:

Dave Lange writes:

A variety is a coin that has characteristics specific to the die pair that struck it. Most collectible varieties can thus be traced to a set of dies.

There seems to be some confusion as to exactly what constitutes a variety. In United States numismatics, a variety may be defined as a die or die pairing that offers some distinctive feature not a normal part of the design. For early U. S. coins, those made before the introduction of the reducing lathe in 1836, every die required extensive hand punching of letters, numerals and other small features. Therefore, each and every die was distinctive, and each die pairing constitutes a variety. Thus, all coins from this period are of some identifiable variety, and each die pairing may be identified by number under NGC's VarietyPlus service.

In the case of modern coins, most features of the design were included in a master hub, from which a series of transfers were made to produce working dies. Very little hand punching was done, aside from the addition of the date and mintmark. Since early in the last century, the date has been an integral part of the master die for each year and has not varied within that year. The same has been true of mintmarks since 1990, and today's coin dies are typically indistinguishable. Though numerous doubled dies, overdates, repunched mintmarks and the like have occurred over the past century, these were the exceptions rather than the rule. Nevertheless, they do qualify as varieties and may be attributed as such under NGC's VarietyPlus service.

NGC utilizes numerous other designations that do not, however, constitute varieties. These include designations such as FH for Full Head, FT for Full Torch and FBL for Full Bell Lines. Likewise, the designations BN, RB and RD for Brown, Red-Brown and Red, respectively, are not varieties.

NGC does not attribute as varieties coins that display Strike Doubling, Abrasion Doubling, Die Deterioration Doubling, Master Die Doubling (doubling that is found on all coins made produced from that master die), insignificant die chips, breaks, cracks or any variety coin that falls under mint tolerances for doubling or normal die wear.

With few exceptions, NGC will not attribute die varieties that require greater than 5x magnification to be clearly recognizable.

To read the complete article, see:
What is a Variety?(https://www.ngccoin.com/variety-plus/what-is-a-variety/)

Bill Eckberg adds:

To read the earlier E-Sylum article, see:
NOTES FROM E-SYLUM READERS: APRIL 4, 2021 : What Constitutes a Die Variety?(https://www.coinbooks.org/v24/esylum_v24n14a07.html)