I’ve counted 13 scales proposed for defining rarity in coins. Only a few are well accepted and none are as universally accepted as the Sheldon scale for grading coins. Perhaps the most common rarity scale is also an adaptation of Sheldon’s scale.
Some rarity scales are merely descriptive of their actual rarity, while others base their judgment on numbers. I think using numbers is a much more accurate than only attempting to describe them verbally.
A version of Sheldon’s Rarity Scale may be universally adopted as the need for quantifying coin rarity increases.
Sheldon’s rarity scale has both a verbal description and numerical description associated with it, similar to his state-of-preservation grading scale. This is really helpful in understanding rarity.
I haven’t found a consensus regarding any of the rarity scales, so I’ve chosen this version of Sheldon’s Rarity Scale, because it uses quantities and descriptions that seem reasonable to me. That leaves both the numbers and descriptions open to debate.
Sheldon Rarity Scale
R1: Over 2000 estimated: Very Common, readily available
R2: 601–2000 estimated: Common, not too difficult to find
R3: 201–600 estimated: Less Common, available at most shows, but in limited quantity
R4: 76–200 estimated: Scarce, somewhat difficult to find, only a few likely at larger shows
R5: 31–75 estimated: Very Scarce, may or may not find at larger shows or auctions
R6: 13–30 estimated: Rare, unlikely to be more than 5 for sale anywhere in a year
R7: 4–12 estimated: Very Rare, almost never seen, only one may be offered for sale in a year
R8: 2–3 estimated: Prohibitively Rare, one may be offered for sale once every 5 to 10 years
R9: 1 estimated: Unique, or nearly so
As you can see, this scale refers to count estimations. It’s impossible to know an exact number. At any time, another coin could surface or disappear and change the figure.
Another useful scale was developed by Q. David Bowers. He calls it the Universal Rarity Scale or URS for short. I think this scale goes beyond simply stating rarity, to measuring the commonness of a coin. This can also be useful.
|Universal Rarity Scale|
|Rarity||Number of known coins|
|URS 0:||None known|
|URS 3:||3 or 4|
|URS 4:||5 to 8|
|URS 5:||9 to 16|
|URS 6:||17 to 32|
|URS 7:||33 to 64|
|URS 8:||65 to 125|
|URS 9:||126 to 250|
|URS 10:||251 to 500|
|URS 11:||501 to 1,000|
|URS 12:||1,001 to 2,000|
|URS 13:||2,001 to 4,000|
|URS 14:||4,001 to 8,000|
|URS 15:||8,001 to 16,000|
|URS 16:||16,001 to 32,000|
|URS 17:||32,001 to 65,000|
|URS 18:||65,001 to 125,000|
|URS 19:||125,001 to 250,000|
|URS 20:||250,001 to 500,000|
C. Scholten developed a scale for rarity in 1953 that I think is less useful than the two above. The Scholten scale depicts the following degrees of rarity, but I can’t find any definition for the descriptions he uses.
|Scholten Rarity Scale|
|Rarity||Number of known coins|
|RRRR||Of the utmost rarity|
So the next time you’re discussing “rare coins”, with another coin expert ask if it’s “R7 or R8 rare” or are we talking R9? If he doesn’t know what you’re talking about, he probably doesn’t know what he’s talking about either. Most rare coin experts are familiar with Sheldon’s Rarity Scale.
Thank you David Kenny for educating me on coin rarity and inspiring me to research coin rarity scales for this article.
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