An 1879 Flowing Hair Stella $4 Proof, valued at $150,000-200,000, is to headline Bonhams' Coins and Medals sale in New York on December 17.
It features none of the striations, typically visible on the obverse, with only a couple visible on the reverse star under magnification - making it possible that this is one of the 15 originals minted in 1879.
The coin was first proposed in the late 1800s when John Kasson, the US ambassador to Austria, suggested to congress the creation of a coin with a value similar to that of the Austrian florin that could be used as an international currency.
The project was shelved in 1880, although a number remained in the US Mint - eventually finding their way into the collectors' market.
Two designs were produced - one depicting Liberty with flowing hair, and the other with coiled hair. The Coiled Hair example is much rarer, with one example selling for $2.5m at Bonhams earlier this year.
This September, an 1879 Flowing Hair realised $194,000 at Heritage Auctions in Long Beach.
A 1795 $10 BD-3 gold eagle features an estimate of $100,000-120,000.
The 1795 Eagles were designed by Robert Scot, with this BD-3 example being the rarest die pairing. There are nine leaves on the wreath in the eagle's beak on the reverse of the coin - changed to 11 in 1796.
Only 500 examples of this pairing were ever struck, with around 20 known to have survived to the present day.
In 2011, a BD-3 example realised $379,500 at Spink in New York - a record for the type.
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