The Denver Mint only struck 180,000 of the 1927-D Double Eagles, far below the over one million pieces for other dates.
It's estimated that only around 3,000 examples of the 1927-D $20 gold coins still exist, making them very scarce.
There are less than 100 known specimens grading Mint State, highlighting the challenge in finding uncirculated quality.
In gem uncirculated MS65 condition, the 1927-D Double Eagle carries a value over $100,000 USD.
The coins depict a striding Liberty design by Augustus Saint-Gaudens, used on $20 gold from 1907 to 1933.
A PCGS graded MS66 1927-D $20 gold coin sold in 2012 for an astounding $1.92 million at public auction.
The low mintage and tiny surviving population makes the 1927-D a famous key date Double Eagle twenty dollar gold coin.