This is a gorgeous vintage sterling silver ring set with a large oval moss agate cabochon. Made by Clark and Coombs, it is in an ornate Victorian style setting with a highly detailed design. It is marked with the Clark and Coombs logo and the word Sterling. It dates to around the mid 20th century.
The ring is a size 5 3/4 (a bit on the larger side of this). It measures about 7/8 inch north to south and it is in very good condition.