Art Deco Rock Crystal, Diamond and Onyx Brooch, Cartier, Paris, circa 1925

Designed as a rectangle of carved rock crystal, the terminals decorated with pierced triangular segments attached by bands, set with numerous old European-cut and single-cut diamonds and 4 marquise-shaped diamonds, with accents of calibré-cut onyxes, the inner border further decorated with diamonds and onyx, mounted in platinum, signed Cartier, French assay marks. With fitted box signed Cartier. 

At the 1925 Paris "L'Exposition Internationale des Arts Décoratifs et Industriels Modernes", Cartier introduced jewelry designs composed of simple geometric forms that marked a break from the previously popular garland style. Eastern influences and changing fashions helped to promote the sleek, simple designs of Deco jewelry, which Cartier began experimenting with as early as 1906. The brooch offered here beautifully exhibits several iconic characteristics of the Deco period. The monochromatic, yet also contrasting, color scheme created by the opaque black onyx, glittering white diamonds and translucent rock crystal, aptly suits the Art Deco taste and was a popular combination at Cartier during the 1920s. Cartier's interest in Eastern and Islamic style also greatly influenced the designs of their jewelry. The detail of the brooch's pyramidal diamond border is similar to that of the latticework of a mosque. Bronze Chinese buckles of the 19th Century acted as a template for Cartier's Art Deco brooches as can be seen in the piece here and is also echoed in the shape of the popular double-clip/brooch.