Carson City double eagles can be neatly divided into three tiers of rarity. The first tier—or what I like to call the Big Five—consists of the 1871-CC, 1878-CC, 1879-CC, 1885-CC, and the 1891-CC. If we assume that most collectors will never buy an 1870-CC due to its rarity and cost, these five issues are the keys to the set.