Natural Australian Red Opal

The Geology of Silica sphere Sizes and Red Play of Color

To understand why red is the most valuable color in the opal spectrum, one must look at its sub microscopic physics. Precious opal is composed of tiny, regularly arranged spheres of silica dioxide. These spheres act as natural diffraction gratings, bending and breaking white light into different colors.

The smallest spheres, approximately 0.1 microns in diameter, diffract light to produce violet and blue. To produce red play of color, the spheres must grow to approximately 0.2 microns – a highly specific, stable geological condition that occurred only rarely during formation. Consequently, red dominant solid stones are extremely scarce. At Opal Galaxy, every red opal is guaranteed solid and untreated, offering outstanding value for custom jewelry or private collections.