A lava, hardstone, citrine and amethyst brooch, by Hedy Martinelli. Photo courtesy Bonhams. Designed as a Chinese dignitary with carved lava head, wearing a headdress composed of carved and fluted hardstones and a citrine briolette, his oval hardstone...

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,...