Extraordinary Boulder Opal Cabochon. Koroit, Queensland, Australia © 2002-2010 Bonhams 1793 Ltd Weighing approximately 188.0 carats and measuring 70.0 x 32.0 x 12.5mm - Sold for $8,540 This is an exceptional and very large, gem-quality pear-shaped cabochon...

Rare Boulder Opal and Diamond Necklace—"The Black Rainbow". Queensland, Australia © 2002-2010 Bonhams 1793 Ltd Designed and fabricated by James Currens. 2009 AGTA Spectrum Award Winner for 1st Place—Phenomenal Gemstone Category Featuring a fancy cabochon...