Unusual variant of the Bague au Firmament 'celestial'style with an enamelled green ground decorated with rose diamond 'stars' bordered by a navette of rose diamonds, supported by it's original 18 carat gold shank, with a makers mark of three letters 'IET'. The central rose is particularly unusual being almost triangular.
Continental c.1820. Size 6. Length of bezel 1.5 inches.
Bague au firmaments ,or 'Ring of Heavens' were first seen in France in the 1780s but the style was popular throughout the c19th with red,green and purple enamel or glass  in oval,navette and oblong bezel shapes.