White opals are renowned for their ability to display a beautiful play-of-color, known as opalescence, which sets them apart from other gemstones. This phenomenon occurs because white opals are composed of sub-microscopic silica spheres arranged in a grid-like pattern. As light waves enter the opal, they bend and diffract around these spheres, causing the stone to emit a kaleidoscope of colors.
The diffraction of light is dependent on the regularity of the spheres’ size and arrangement, meaning that no two opals will exhibit the same pattern of color, making each stone unique. It’s the mix of the background color, which ranges from milky to white in these opals, with the flashing colors, which makes white opals highly sought-after. The most magnificent examples of white opal will exhibit a vivid spectrum of colors that are bright and distinct across the surface of the stone.
