What This Coin Looks Like (Obverse, Reverse, Mint Mark Location, Special Features, etc.): There were two major varieties of the 1907 High Relief $20 Saint Gaudens Gold Double Eagle. One variety features a "Flat Rim" (as depicted above) while the other featured a "Wire Rim".
The Wire Rim variety features a very thin and raised rim at the very outer rim of the coin - whereas the Flat Rim variety does not have this thin raised wire rim. In order for a coin to qualify as "Wire Rim" - the raised wire rim needs to be present through the entire circumference of the coin. The difference between the Wire Rim vs Flat Rim is depicted below in the example comparison image (Source of example images is courtesy of Heritage Auction Galleries):
Coin Value Chart: Typical Coin Prices, Values and Worth in USD based on Grade/Condition