Gold coins come from many countries in many denominations and sizes. United States gold coins have been around for a few hundred years. The United States has numismatic collectible coins that are collected and traded for the date, rarity , mint mark and condition, as well as bullion coins which are mostly for their intrinsic bullion weight value.
The more common United States gold coins that people collect are the Double Eagle $20.00 gold piece which was made in the Liberty Head design & the St. Gaudens design. Their gold content of 0.9675 troy oz was worth $20 at the then official price of $20.67 per oz. and are made from a 90% gold (0.900 fine = 21.6 kt) and 10% copper alloy
The Liberty Head $20.00 gold coin was made between 1849 -1907 and was made in three variations: Liberty Head, no motto, “Twenty D.” 1849–1866, Liberty Head, with motto, “Twenty D.” 1866–1876, & Liberty Head, with motto, “Twenty Dollars” 1877–1907. The beautiful St. Gaudens $20.00 Double Eagle gold coin was made from 1907-1933 – Saint Gaudens, High Relief, Roman Numerals, no motto 1907, Saint Gaudens, Low Relief, Arabic Numerals, no motto 1907–1908,Saint Gaudens, Low Relief, Arabic Numerals, with motto 1908–1933.
The Liberty Head gold coins were also made in smaller denominations called : Eagle $10.00 , Half Eagle $5.00 & Quarter Eagle $2.5 dollar the design was like the larger Liberty Head $20.00 Double Eagle but graduating smaller in size and were minted at various mints. There were three $1.00 variations Type l , ll & lll , as well as a $3.00 gold coin
When they changed the design of the $20.00 Liberty to the St.Gaudens they also designed new $10.00, $5.00 & $2.5 dollar gold coins. These were called Indians. The $10.00 Indian was first made in 1907 and has a different Indian and eagle on it than the smaller $5.00 & $2.5 dollar Indians do. It was a raised design versus the incuse design of the smaller $5.00 & $2.5 Indian gold coins.The $5.00 & $2.5 dollar Indian gold coins were made starting in 1908 a year after the St.Gaudens & $10.00 Indian , they were also minted in various mint branches . The Liberty Head , Saint Gaudens & Indian gold coins are not the only coins the United States made but are the most popular gold coins collected and are graded and sold by their condition and date rarity and can and do surpass the intrinsic bullion value in most cases unless the coin was harshly cleaned, polished, set in jewelry ,damaged, holed, or in such bad condition then in those cases it would only be traded on its bullion value.
The United States has bullion coins specifically for investing in gold as a commodity , they include Gold Eagles 1 ounce, half ounce, quarter ounce and 1/10th ounce. They are made in Proof and Mint condition. Over the years a few have become collectible due to low mintage but these primarily are bullion gold coins bought and sold for investing in gold intrinsic value. They also make a Platinum Eagle platinum coin that also comes in Proof and Mint condition. There are many other United States bullion gold coins like the Buffalo, Olympic coins and many more, but Eagles are the most popular.