What The Numbers Mean

Learn how to use those confusing numbers often seen in identifying errors and die varieties.

By J. T. Stanton, N.L.G.In the study of mint errors and varieties, identification numbers appear more abundant than with the regular segment of the hobby. These can seem to be very complicated and confusing. The numbers are simply easy methods of precisely identifying various varieties. By using these numbers, other specialist can quickly and easily determine exactly which variety is being mentioned. Other numbers are used to describe rarity, and even a certain class or type of variety. But the important fact is that with the use of the numbers, most people can mention a certain identification number, and most dealers and collectors can know right away exactly which variety is being mentioned. At the very least, a dealer or collector can look in popular reference sources and find that corresponding number along with a photo or photos, which helps them in their quests for knowledge.

Most of these identification systems are simply numbers listed after the date and denomination. Some are more complex identification listings and include letters or symbols to further identify the variety or error. Additionally, some of the identification listings can be confusing, as a couple may use the same prefix. In this case, one must be able to assume which identifier the writer is mentioning. But this can usually be done relatively easy.

RPM and OMM listing numbers

(Repunched mintmarks and Over mintmarks)
These are the original CONECA RPM and OMM listing numbers. CONECA is the acronym for the Combined Organizations of Numismatic Error Collectors of America, the long-time national error and variety club. You will notice that most RPMs (repunched mint marks) and OMMs (over mint marks) are identified simply, such as 1938-D/S 5c, OMM #1. These numbers simply indicate that the coin is a 1938-D nickel, with an over mint mark (D over S), and is over mint mark #1. This indicates that it was the first OMM listed for that particular date by John Wexler and Tom Miller when they originally produced The RPM Book in 1982. However, just because is was the first listed, that in no way means that it is the strongest, the most desirable, or the most valuable, although that is usually the case. The RPM Book has become the standard in the hobby for RPM and OMM reference. Even though published in 1982, it is still the most important reference for mint mark varieties as of the year 2003.

The same holds true for repunched mint marks. If a coin is listed as a 1960-D 1c RPM #1, it simply means that the coin is a 1960-D cent, and is the first RPM listed for the date. RPM #1 does not necessarily indicate that the RPM is the strongest or the rarest, only that it was the first one to be listed.

Doubled die listing numbers

As with the RPMs and OMMs, the doubled dies are also assigned numbers which correspond to the listing numbers in the CONECA files. This numbering system was developed by Alan Herbert and John Wexler. These numbers can be confusing to the beginner, but the numbers have a very logical and important sequence for the collectors, so a brief explanation is included herewith.

The study of numismatics cannot be complete without a good working knowledge of the processes used to manufacture coins, currency, tokens, and other instruments of trade. With the study of mint errors and varieties, a knowledge of the minting process is even more critical. And in order to understand varieties, a working knowledge of how the dies are made is critical in being able to determine whether some coins are in fact doubled dies or the result of some other abnormality.

There are eight basic classes of doubled dies. These classes have nothing to do with the strength of the doubling, but rather indicate how the particular doubling occurred. Because of the complexity, the “how” is covered in other references, and is not as important to most collectors as is the strength of the doubling. But consider this; there is a Lincoln Cent listed as 1971-S PF 1c 1-O-II. These numbers indicate that the coin is a 1971-S Proof 1c, listed as die #1, with the doubling on the obverse, and it is a class II doubled die. As with RPMs, if the coin is die #1, it does not necessarily mean that it is the strongest doubled die for that date, only the first one listed. The sequence for these doubled die listing numbers will always be the same. Following the date of the coin will be the indication of a proof (if it is a proof), then the denomination, the die number (indicated by Arabic numerals), an “O” or “R” signifying the doubled die on the obverse or reverse, then finally the class of doubled die (indicated by Roman numerals). There are some doubled dies which were made as a result of a combination of more than one class such as 1971-S PF 1c 2-O-II+V-CW. The “CW” at the end indicates the spread (from the Class V doubling) is in a clockwise direction. Class I and Class V doubled dies will be indicated with a CW or a CCW, indicating either clockwise or counter-clockwise spread. And yes, the direction of the spread is important in determining, in many cases, which doubled die it is. There are also cases in which a coin will have a doubled die on the obverse and reverse, such as 1963 25c 7-O-II +1-R-I. As mentioned above, these identification numbers should become easy to understand.

A more detailed description of each doubled die class is published in The Lincoln Cent Doubled Die by John Wexler. This book is highly recommended for all variety enthusiasts. Although published in 1984, it is still a valuable source of information, and a must for variety collectors. A section on the die making process will be added to this web site.

Other numbers

Other numbers are used from time to time usually to indicate a listing number as derived from a known and respected reference work. A list of some of these reference numbers follows. This list may not complete, as other books also have reference numbers, and more books and reference works are being produced constantly.

  • Breen - Listed in Walter Breen’s Complete Encyclopedia of U. S. and Colonial Coins.
  • F - Fletcher, varieties as listed in Ed Fletcher’s book The Shield Five Cent Piece
  • FS - Fivaz/Stanton, listed in The Cherrypickers’ Guide.
  • S - Snow, listed in Flying Eagle and Indian Cents, by Rick Snow.
  • VAM - Van Allen/Mallis, Morgan and Peace Dollars as listed in

    Comprehensive Catalog and Encyclopedia of Morgan and Peace Dollars.

  • Leone - listed if Frank Leone’s Longacre’s Two Cent Piece Die Varieties and Errors.
  • Sheldon - Listed in Penny Whimsy by William H. Sheldon
  • WB - Listed in The Complete Guide to Liberty Seated Half Dollars by Randy Wiley and Bill Bugert

Rarity factors

The Sheldon Scale C For many years, the only method of reasonably identifying rarity was with the use of Sheldon Scale. This scale was designed at the time to identify rarity of Large Cent varieties. In this case, the Sheldon Scale worked very well, as mintage figures were relatively low. No question. The Sheldon Scale was further adopted for use with many other series and denominations, as it was the only common scale in existence. However, it was not quite appropriate for most series, most varieties, or even most errors in today’s hobby.

The Sheldon Scale was simply a progression of eight levels, in which the population of all Large Cent varieties were to fall, and was prefaced with the letter “R”, indicating Ararity.

The Sheldon Scale

  • R-1 Common
  • R-2 Not So Common
  • R-3 Scarce
  • R-4 Very Scarce (population est. at 76-200)
  • R-5 Rare (31-75)
  • R-6 Very Rare (13-30)
  • R-7 Extremely rare (4-12)
  • R-8 Unique or Nearly So (1, 2 or 3)

As we indicated previously, other writers adopted this scale to represent coins that were considered scarce or rare, however, as you can imagine, the scale would not be appropriate for many coins today. For instance, if using this scale, the 1955 doubled die Lincoln Cent would be considered common or not so common. Yet in today=s market, the coin is in fact scarce or rare. It all has to do with that which is relative.

The Universal Rarity Scale by Q. David Bowers

It is quite obvious from the above that another scale was desperately needed by the hobby for indicating rarity of all coins. Leave it to Q. David Bowers to recognize the need, and develop a method that could be used for any series, and any rarity. In fact, this can be used not only with coins, but with virtually anything when rarity, scarcity, or availability was important. Bowers developed The Universal Rarity Scale (URS), which as its name implies, is universal for any coin or item. Bowers outlined his scale in the June 1992 issue of the Numismatist. It has already been adopted by many writers and catalogers, including exclusive use in the Cherrypickers= Guide.

The URS is a reasonable mathematical progression. One does not need to have a copy with him or her to be able to determine a correct URS. Just simply remember the easy progression.

The Universal Rarity Scale

  • URS-0 None known
  • URS-1 1 known, unique
  • URS-2 2 known
  • URS-3 3 or 4 known
  • URS-4 5 to 8 known
  • URS-5 9 to 16 known
  • URS-6 17 to 32 known
  • URS-7 33 to 64 known
  • URS-8 65 to 125 known
  • URS-9 126 to 250 known
  • URS-10 251 to 500 known
  • URS-11 501 to 1,000 known
  • URS-12 1,001 to 2,000 known
  • URS-13 2,001 to 4,000 known
  • URS-14 4,001 to 8,000 known
  • URS-15 8,001 to 16,000 known
  • URS-16 16,001 to 32,000 known
  • URS-17 32,001 to 65,000 known
  • URS-18 65,001 to 125,000 known
  • URS-19 125,001 to 250,000 known
  • URS-20 250,001 to 500,000 known

As you can see by the Universal Rarity Scale (URS), the mathematical progression is simple, and can be applied to any item as an indication of rarity. In addition, the scale, being simple, does not require memorization, as one can figure what population a URS number indicates.

When using rarity numbers with coins, there are a couple of important things to remember. One, rarity generally differs from one grade to another. If a coin is listed as URS 13 (2001 to 4000 known), it may be relatively common. However, if there are only 2 known in grades above AU, it would be a true rarity in MS63. Such is the case with the 1888-O Morgan Dollar, “hot lips” variety. They are fairly common is VG and F, but virtually unknown above AU. Secondly, rarity and value are not as closely related as one might suspect. If there are 10 examples of a particular variety known, but only 7 or 8 collectors interested in obtaining a copy, the coin would certainly be rare, but because of a relatively low interest factor, it would not command much of a premium. Conversely, there could be many thousands of a variety known, but if many thousands more collectors were interested in obtaining a copy, the premium over the normal value of the coin would be greater due to the high interest factor (demand). This brings us back to the old theory of supply and demand.

Interest factor

Interest factor is a term used at times to indicate just how much demand a particular coin or variety might have. A coin with a very high interest factor would be in high demand, with several thousands of collectors desiring it. A medium interest factor may indicate that the coin is desired by hundreds or a few thousand people, and a low interest factor might indicate that the coin is sought by just a handful of collectors.

Interest factor, combined with the rarity, help to determine the value of a particular coin. However, the eye appeal of the coin is also a contributing factor and must be considered in the final evaluation. With varieties and errors, a very important part of eye appeal is the relative strength or visibility of the particular variety or error – how easily can it be seen?

As a variety receives more publicity within the numismatic press, the Interest Factor may rise as demand increases. This may cause the price or value of certain varieties (and errors) to increase without any change in the estimated quantity available. On the other hand, if a large quantity of a variety surfaces, the value of that variety may decrease as the supply outstrips the demand.

As in other segments of the hobby, a combination of supply and demand almost always dictates the price or value of a particular variety.

Liquidity factor

The Liquidity Factor is a measurement developed by J. T. Stanton to indicate how quickly or how easily a coin or variety should sell at auction, given normal market conditions. Using a scale of 1 to 5, a Liquidity factor of 1 would indicate that the coin would not normally sell very easily or fast, and usually at a discount from suggested values. A Liquidity factor of 5 would be expected to sell right away, and generally command full or inflated values. Hot or highly active market conditions would usually inflate the liquidity of any coin, with a cold market causing the opposite.


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