A lava, coral and diamond brooch, by Hedy Martinelli. Photo courtesy Bonhams. 

Modelled as a Chinese man, his clean-shaven, laughing face carved in lava, wearing a branch coral (corallium rubrum) headdress and robe with brilliant-cut diamond decoration, diamonds approximately 0.95 carat total, length 7.8cm, maker's suede pouch. Estimate £1,400 - 1,800 (€1,700 - 2,200)

"Bob and I discovered the amusing and whimsical jewellery designs of Hedy Martinelli in the 1990s. This Roman designer crafts many of her pieces from unusual materials, including lava. When Bob saw this unique brooch by her, he realised it would match a pair of orange enamelled earrings studded with peridots, which he had purchased earlier. It was the coral turban which linked them. Hedy Martinelli's "heads" are a modern take on the blackamoor brooches of Venice, and whenever I wore one everyone was fascinated and asked where I had bought it. In fact, most of her jewellery designs are talking points."

Gift from Robert Bradford in 1999 to celebrate Barbara's birthday.

Bonhams. FINE JEWELLERY INCLUDING SELECTED JEWELS FROM THE COLLECTION OF BARBARA TAYLOR BRADFORD. London, New Bond Street. 5 Dec 2013 - www.bonhams.com