A suite of 13 black opals made $72,500 at the World of Opals sale at Bonhams Los Angeles on December 10.
The collection originates from a single seam in Lightning Ridge in New South Wales, Australia, with each stone displaying a pattern of blue and green interspersed with brilliant flourishes of orange.
Another significant black opal, named The Road to Lightning Ridge, achieved $56,250 in the sale.
It features an astonishing range of colours, with reds and oranges predominating, and is cut into an oval cabochon.
Around 97% of the world's opals are found in Australia, with Lightning Ridge one of the few places where black opals can form. The world's largest, the 306 carat Royal One, valued at $3m, was uncovered there in 1999.
In terms of gem opals, which are rare but much more widespread than the black opal, the Olympic Australis holds the current record, weighing in at an enormous 17,000 carats (over 3kg).
The reason for the high concentration of opals in Australia can be partly attributed to the Great Artesian Basin - an enormous mineral-rich freshwater deposit that underlies much of the eastern part of the country.
A pair of boulder opal cabochons sold as a single lot for $43,750.
They were discovered in Winton, Queensland and exhibit bright red colouring that fades through to blue. Together they weigh over 40 carats and have been cut into triangles.
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