A 1907 proof gold double eagle led a line-up of rare coins at Bonhams' June 2 sale in Los Angeles, achieving $222,300.
Augustus Saint Gaudens designed the issue, which initially featured an ultra high relief finish.
The exact number of proofs struck remains a mystery, with the world's grading companies divided on whether the few slight minting variations extant can be classified as proofs at all.
Bonhams explained: "The existence of true satin Proof coins is controversial. [Grading company] NGC recognizes this High Relief Proof but PCGS does not."
One of the ultra high relief variants sold for $1.1m at Heritage in August 2012.
An 1859 $20 proof cameo was another highlight, achieving $210,600.
There are thought to be around 80 such proofs minted that year, with 10 known to have survived in a variety of grades.
The already scarce coins were further thinned by the effects of the civil war, which began two years later in 1861 and resulted in the majority of collectors selling or trading in their collections for the gold value.
Other significant lots included a 1915-S Panama-Pacific $50 Round, which sold for $71,370.
The coin was issued in both round and octagonal versions, with just 1,500 examples of each ever produced. Their unusual faux-Greek design, combined with their rarity, resulted in them becoming hugely popular among collectors.
We have an exciting range of rare coins available.
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