gold ring with diamond and ruby

An 18 carat ring with a cluster of 9 brilliant cut diamonds (app. 1.4 carat in total) and two ruby swirls around (app. 4 carat in total) with a French master mark: SG, France circa 1950.

weight: 13.31 grams
ring size: 17.5 mm / 7 1/4 US