British Sovereigns have been issued for nearly 200 years.
The value of any Sovereign would depend on its year, place of minting and its condition.
There were no 1800 British Sovereigns minted. The Sovereign was reintroduced into the British currency in 1817 after an absence of about 200 years.
There was a total of 30,044,000 1911 British Sovereigns minted for circulation.
There were 2.95 million 1982 British "Uncirculated" Sovereigns minted. There were 20,000 1982 British "Proof FDC" Sovereigns minted.
The were approximately 2,718,000 British 1838 gold Sovereigns minted.
Isle of Man Sovereigns and Half-Sovereigns are very similar, but not exactly identical to British Sovereigns and Half-Sovereigns. The Isle of Man Sovereign is 22.5mm in diameter and the Half-Sovereign is 19.5mm in diameter.
There were about 10,041,000 British 1904 Sovereigns minted at the Royal Mint London (no mintmark). There were about 3,743,000 British 1904 Sovereigns minted at the Melbourne Mint (mintmark = M to the right of the date). There were about 4,506,000 British 1904 Sovereigns minted at the Perth Mint (mintmark = P to the right of the date). There were about 2,986,000 British 1904 Sovereigns minted at the Sydney Mint (mintmark = S to the right of the date).
Sovereigns were not in circulation in 1692.
There were no British Half-Sovereigns minted from 1938 to 1979 inclusive.
99 years as of February 2010.
There were no 1804 British Sovereigns minted. The Sovereign was reintroduced into the currency in 1817.
There was no British Half-Sovereigns minted from 1927 to 1936 inclusive.
Pictures of a specific coin are difficult to come by. Frequently you should be able to find one on eBay, but the picture is withdrawn after the coin is sold. All British Sovereigns from 1893 to 1901 inclusive are pretty much identical except for the year. Sovereigns are near identical to Half-Sovereigns from the same period, Half-Sovereigns being a few millimetres smaller in diameter. See the link below for an 1894 British Half-Sovereign.
British 1990 to 1999 22 carat gold Sovereigns (Proof FDC) could fetch up to £450 GBP. The values quoted are the best possible for the best specimens in their grades, but may be significantly lower due to varying demand for the coin and the prevailing economic climate. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.