| A | Abundant,
readily available, often in wholesale quantities. |
| C | Common,
always available. Occasionally in quantity. |
| R1 | Usually
available without a long delay. Difficult to find in quantity. |
| R2 | Scarce
to rare, less seldom available. |
| R3 | Rare.
Difficult to find. |
| R4 | Very
rare. Demand outstrips supply, and specimens, when available are often eagerly
sought. |
| R5 | Extremely
rare and seldom available. Collector may have to search for a few years to locate
one. |
| R6 | Of
the highest rarity. Very difficult to obtain. |
| R7 | Almost
never available. Most collectors will not have a chance to acquire these pieces. |
| R8 | Never
been on the market. Almost impossible to obtain. |
| R* | Not
available for collections. |
