Rare American Coins Get Weighed on a Rarity Scale

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.

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 1:

1

URS 2:

2

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

C

Common

N

Normal

S

Scarce

R

Rare

RR

Very Rare

RRR

Extremely Rare

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.

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