This is one of the so called "gypsy" rings. It's a band of 18 carat gold , set with two small sapphires, and a diamond. The shape of the band is typically Victorian; The hallmarks are clear and visible, showing this ring to be British 18 carat gold, minted in Chester, in the year 1908/09. It is a size 6 and 3/4, but it could be re sized.
Gypsy Band Ring, Sapphire and Diamond, Edwardian