Halley's Comet, a significant black opal, is estimated to make $450,000-650,000 at Bonhams' World of Opals sale in Los Angeles on December 10.
The 2,000 carat stone, which is roughly the size of a man's fist, is recorded in the Guinness Book of World Records as the world's largest uncut black opal nodule.
It was discovered in Lightning Ridge in New South Wales, Australia on November 3, 1986 as Halley's Comet appeared in the sky.
The area of Lightning Ridge is a hotspot for black opals, a reference to the dark background of the stones, and has been mined since the early 1900s.
Halley's Comet is the largest found in the area and is known internationally as one of the finest quality black opals, in terms of both its size and colouring.
It exhibits a thick black gem-grade opal colour bar paired with a harlequin pattern of green, blue/violet and yellow.
Around 97% of the world's opals were found in Australia, including the Olympic Australis, the world's largest opal at 7,000 carats, which has been valued at $2.2m.
A black opal and diamond pendant brooch by David Webb is valued at $120,000-150,000.
It features a large Lightning Ridge black opal shot through with a blue, green, orange and floral pattern and broad flash play-of-fire.
Weighing in at 190 carats, the opal is encircled by 96 shaped diamonds with the reverse of the mount textured with hammered gold.
Bonhams' last World of Opals sale was topped by The Black Prince, which realised $134,500.
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