White Opal vs Boulder Opal

White opal is a variety of precious opal characterized by a white, milky, or light-colored base tone upon which internal spectral colors flash, a phenomenon known as play-of-color. The internal structure of this hydrated silica diffracts light to produce the shifting displays of color that make the stone distinct. It is predominantly mined in the Coober Pedy region of South Australia, which is wid...

Boulder opal is a distinctive gemstone variety found exclusively in Queensland, Australia, characterized by its formation on ironstone host rock. Unlike solid opals, these gems are cut and polished with the natural ironstone matrix intact, resulting in a dark backing that enhances the stone's vibrant play-of-color. This structural composition creates unique, swirling matrix patterns within the gem...