Boulder Opal: Desirable & Valuable jewelry. Fantastic Boulder Opal is a spectacular variety of Opal, primarily found in Queensland, Australia. The vibrant interplay of colors makes this variety most desirable and valuable. The natural iron base of the stone gives it stability and contributes to its high durability. The varying and interesting natural shapes make the gem a perfect pick for unusual Boulder Opal Jewelry designs. Visit: https://www.rananjayexports.com/gemstones/boulder-opal