Modern Sovereigns
For all modern gold sovereigns, i.e. from 1817
Diameter: 22.05 mm.
Thickness (Depth) 1.0 to 1.4 mms.
Weight: 7.9881 grams.
Alloy: 22 carat gold = 0.917 parts per 1000.
Actual gold content = 7.3224 grams or 0.235421 troy ounces.
Date first issued in current format: 1817
First date ever issued: 1489

The Sovereign
An excellent book for further information about sovereigns.