A homogenous black and white opal and diamond brooch: the oval opal stated to be approximately 21.67cts and set within a revolving collet displaying the white opal front and black opal back, within a millegrain mounted, rose-cut diamond frame with ribbon bow surmount, 4.1cm total length of brooch, accompanied with a report from 'The Gem Testing Laboratory' stating the opal is a 'natural homogenous opal', report number '105649' and dated '17-9-81'.