Bague au firmament
A most extraordinary example of a bague au firmament ring, circa 1780. The gold shank supports a plaque of foiled Byzantine purple glass. At the centre of the plaque is a single emerald cut into facets, inset with a large rose-cut diamond of approximately 3/4 of a carat, within a surround of rose-cut diamonds. The plaque is also within a border of rose-cut diamonds. The ring is size K and 1/2 [US 5 and 3/8] and the head of the ring measures 1 and 1/8 inches by 3/4 of an inch. Absolutely luscious and such a rare colour combination.