For all gold sovereigns post 1817, the specifications are:
diameter: 22.05mm
Weight: 7.98 grams
Alloy: 22 carat gold = 0.917 parts per 1000
Actual gold content = 7.315 grams or 0.2354 troy ounces
Although the U.K. stopped producing gold sovereigns in 1914 (gold was needed for The War), branch mints continued to produce sovereigns, Ottawa in Canada until 1919, Bombay in India in 1918, Sydney (Australia) until 1926, Melbourne and Perth (Australia) until 1931, and Pretoria (South Africa) until 1932.
From 1957, bullion sovereigns were issued almost every year until 1968, then not until 1974 when regular production was restarted.
Many different designs have been used on the gold sovereign coin but the most famous is undoubtedly the "Saint George and the Dragon" that was introduced in 1817 and is still being used today. It was designed by an Italian artist and engraver, Benedetto Pistrucci.
more info: http://www.goldsovereigns.co.uk/