The 1850 Double Eagle {$20} gold coin was produced at 2 US mints: Philadelphia which is shown as 1850-P in this list and New Orleans which is shown as 1850-O in this list. To determine which coin you have it is necessary to locate the mint mark. This mark is a single, small letter and can be found on the reverse [tails] side of the coin just below the eagle. The letter "O" is for New Orleans. If there is no letter just below the eagle then the coin was minted in Philadelphia. The circulated and uncirculated values for these coins are shown in the following list:
Circulated Grades.....1850-P............1850-O
VF30...........................$1650.............$2750
EF40...........................$1950.............$6750
AU55..........................$6000.............27, 500
Uncirculated values
MS60..........................$11,500............$57,500
MS62..........................$32,000................none
MS63..........................$47,000................none
MS64..........................$80,000................none