Varieties and Mint Marks: – Check for any distinctive features, varieties, or mint marks. Different minting facilities might have produced variations in the design or included mint marks that could affect the coin's rarity.
Condition: – The overall condition of the coin can impact its uniqueness. A well-preserved, high-grade coin might stand out from others of the same type.
Expert Opinions: – Seeking opinions from numismatic experts or professional graders can help identify any unique features or characteristics that contribute to the coin's rarity.
If you have specific details about what makes the 1866 Seated Liberty Quarter unique, it would be helpful for a more accurate assessment.
Due to the fact that there are only five known examples, its rarity cannot be disputed. Over $3.7 million was the price at which one of these nickels was sold in 2010, and its worth has continued to increase since then.