When the last 1803 Draped Bust Dollar was struck it took 37 years before another dollar denomination was minted for circulation. So it was in 1840 that the first Seated Liberty Dollar was struck and this lasted 33 years until this series was last minted in 1873 and replaced by the Trade Dollar in 1874.
It's should be noted that from 1840 through 1865 the Seated Liberty Dollar did not has the motto "IN GOD WE TRUST", but it was added in 1866 due to legislation. However this created a rarity, in 1866 some Seated Dollars were struck without a motto on the reverse, and only two are known. Another rarity is the 1870-S with only 12 known (PCGS.com) and each one is valued from $700,000 and up to $2,700,000.
All dates and mints of this series are worth a coupled hundred dollars and up, depending on condition and grade of the coin, but there's some other valuable key dates as well. The keys are as follow: 1851, 1852, 1871-CC, 1872-CC, 1873-CC and they're valued in the thousands of dollars. Reports of 1873-S Seated Dollars are known but not one single example has turned up and when they do they've been fakes.
You have proofs struck for every business strike year plus there were proofs struck in 1836 and 1839, and proofs from 1857 and ealier are extremely rare and worth anywhere from $10,000 to $175,000 depending on their condition.
Since the value of Seated Dollars depends as much on the grade as the mintage then it's important to have an idea on what they look like in different grades and you can do that here PhotoGrade Seated Dollars
If you got the grade and it's problem free (not cleaned, scratched or damaged) then check out how much it's worth Seated Liberty Dollar Values. If you can't find the date and mint in our price list then your coin might be a fake and you will want to check a few things out here ID Fake Seated Dollars
Designer: Christian Gobrecht
Diameter: 38.1 millimeters
Silver - 90%
Copper - 10%
Weight: 26.73 grams
Mint mark: None (for Philadelphia) below the eagle on the reverse.