Vintage Grosse solid silver and agate square signet style ring

A vintage solid silver ring featuring a flat tablet of agate showing some white stripes and moss like inclusions set in a stepped bezel on a wide tapered signet style ring shank - marked Grosse for Henkel and Grosse of Germany - total weight 17.6grms  - dimensions of face 23 x 23mm - currently size approx L AU/UK (US 5.5) - due to design limited resizing available - please enquire - c.1975 Germany