For those who don’t know, Lightning Ridge in Australia is the main source for black opals. Black opals have a dark background, as opposed to a white one like we normally see, and the Lightning Ridge opals are famous for a beautiful play of color on that dark background.
Black opals are pretty rare. When they form, they form in a darker quartz-like layer that brings more refraction to the top of the opal, so you can see a vivid display of color. In most opals, red is the most sought-after flash of color, though greens and orange and even blue are pretty common.