Natural White Opal from Coober Pedy Australia 9.06ct 25x15mm Teardrop Cabochon

A large teardrop at 25x15mm, cut shallow and broad from Coober Pedy light opal. The body is a milky white with a faint honey warmth through the thicker part, and across the middle and lower half runs a dense field of vivid grass-green pinfire, tightening into brighter clusters toward the base and cooling to blue-green along the left edge. Natural texture in the material shows as fine sandy lines and one small pale patch near the center, both normal in Australian light opal and part of how the stone reads.

The green comes from diffraction through ordered silica spheres, and the tight pinfire pattern tells you those ordered regions are small and closely packed. Coober Pedy in South Australia has been mined since 1915 and is the classic source of white and light opal. Unlike Ethiopian material, Australian opal is not hydrophane and does not absorb water, which makes it more forgiving in wear. This stone is untreated. At 9.06ct it has the size for a statement pendant, and opal's 5 to 6.5 hardness is best served by a bezel or otherwise protected setting. Opal is the October birthstone.

Natural white opal, Coober Pedy Australia, untreated, sold loose.