A diamond brooch 'au firmament', late 18th century

A diamond brooch 'au firmament', late 18th century, the central diamond cluster on a blue glass plaque set with diamonds in star-shaped collets, within an elaborate scrolling surround of graduated old pear-shaped and cushion-shaped diamonds in closed-back silver settings, length 4.5cm, later brooch fitting, blue glass with hairline crack, case

Provenance: the collection of the late Michael Wellby, Sotheby's London, 11th December 2012, lot 29

The 'Bague au Firmament', or 'Ring of Heaven' was designed to celebrate the news that Louis XVI and Marie Antoinette were expecting an heir - the dark blue glass representing a night sky dotted with diamond-set stars. Marie Antoinette was known to wear her own 'Bague au Firmament' almost every day. The style grew in popularity and spread beyond its native France in the late 18th century and early 19th century, incorporating floral and geometric motifs, and adapting to fit brooches and other jewels.