Related Clues:
- Describing a numismatist's treasure
- Least cooked
- Most collectible
- Least common
- Like AB negative, of all major blood types
- Most unusual
- Most infrequent
- Least available
- Least seen
- Superlatively scarce
- Most valuable, perhaps
- Least likely to be spotted
- Least prevalent
- Superlatively slippery
- Hardest to find