What this coin looks like (obverse, reverse, mint mark location, special features, etc.): The 2009 Saint Gaudens $20 Double Eagle is a realization of coin designer Augustus Saint-Gauden's dream of producing an Ultra High relief version of his coin - which he and many others considered to be the most beautiful of all US and world coins. Unfortunately the coin minting technology that was available to him in 1907 was limited and was inefficient at producing high-relief coins at the time. Only a handful of them were produced (most later destroyed) but the impractical coin producing technique was abandoned in favor of a low-relief coin - which was easier and more efficient for the US Mint to produce.
In 2009: With the vision of Mint Director Ed Moy and modern technology - the Us Mint digitally mapped Saint Gauden's original design for the coin. A few more features were added including 4 more stars to make a total of 50 stars on the obverse of the coin for each US State in our time. The words "IN GOD WE TRUST" was also added to the reverse of the coin - these words were not in the original 1907 design. The lettered edge of the coin features the words "E PLURIBUS UNUM" with stars between each letter.
Other major changes: The gold composition content was changed from 22 karat (90% gold) to 24 karat (99.99% gold). This made it easier to strike the coin with ultra-high relief as gold is a soft metal and more malleable. The weight is 31.10 grams or 1 troy ounce. The diameter was slightly reduced to 27mm and the coin is 4mm thick. The end result is a stunning and spectacular ultra-high relief gold coin - which truly is one of the most beautiful coins ever made.
Nearly all of these coins are graded MS-68 and higher with MS-70 grade coins being the most valuable as the ultra-high relief strike is extremely high quality. Proof-like (PL) coins command a higher value in MS-68 and MS-69 condition. PL graded coins are significantly rarer and more valuable in MS-70 grade - commanding nearly twice as much value as MS-70 non-PL grade coins.
Coin value chart: Typical coin prices, values and worth in USD based on grade/condition