Centering an oval opal measuring app. 8.5 x 5.3mm, framed by ten Old Mine cut diamonds weighing app. 1.20ctw., with ornate shoulders and black enamel* detailing, fashioned in 18k. Circa 1870. Size 5.75*Although vitreous enamel forms a hard, durable surface, it is susceptible to chipping and breaking upon impact. **Some enamel missing.