Koroit Nut Boulder Opal // 217.5 Carats

This exquisite over 40-gram Koroit nut boulder opal from Queensland, Australia, is a premier AAA specimen of one of the world’s most highly coveted opals. Second only to the elusive black opal in rarity, boulder opal is renowned for its mesmerizing play of color, and this piece is no exception. Its rich brown ironstone matrix is intricately threaded with striking veins of electric purple, green, and yellow opal, creating a dynamic and luminous effect. A true collector’s piece, this opal will add depth and brilliance to any fine mineral collection. Explore its breathtaking beauty in our gallery.
Interesting Facts
Boulder opals are uniquely embedded within ironstone, enhancing their structural integrity and making them ideal for both collection and jewelry use. The Koroit opal field in Queensland is world-famous for its intensely patterned and vibrantly colored specimens. The shifting play-of-color seen in opals is caused by light diffraction through microscopic silica spheres, creating the gemstone’s signature spectral brilliance.
Features
Origin: Koroit Opal Field, Queensland, Australia
Material: Boulder Opal in Ironstone Matrix
Condition: Natural, highly reflective AAA specimen
Special Characteristics: Electric purple, green, and yellow opal veins woven through ironstone
Dimensions and Weight
Height        Length        Width        Weight
2"        1"        0.75"        217.5 ct
Just in Astro West.