Black opal and diamond ring, mid 20^th century. Black opals are so-called as their colours flash against a dark body colour. The contrast between the bright colours and the dark background is the reason why black opals are the most highly prized of all opals. Sourced from Australia, most notably the area known as ‘Lightning Ridge’, black opals were first discovered in the 1880s, but due to their rarity their production fluctuated over the course of the 20^th century. The joy of opals is that their plays of colours are all unique, like a fingerprint. This opal is of generous size, with large flashes of green and deep blue covering the majority of its surface, and a vein of reddish orange across the centre – a beautiful and vivid display. The shoulders are set with early 20^th century diamonds in millegrain-bordered settings, their flame motifs echoing the opal’s colourful display.