A late 20th century hardstone and silver ring

A late 20th century hardstone and silver ring, designed as a revolving tower of circular discs, the five upper most graduated in size and each set with a different hardstone, to the bifurcated shank, hallmarked London 1989, maker's mark approximately SGC, size K ½ approximately, together with a silver part textured motif pendant attached to a leather cord necklace