This is a vintage blue/gray Japanese saltwater akoya cultured pearl ring.

The pearl is 6.75mm round. It has good luster with bright rosy overtones and is a light blue/gray color. It is set among leaves and a textured band that goes two thirds the way around the band. 

It is set in solid sterling silver. It is stamped "STER". US size 7. From the 1950's-1960's.

All pearls are truly vintage and have only been lightly cleaned. Some tarnish and patina on metal.