Opalised mussels found near Lightning Ridge.(Supplied: Bob Smith) Common opal can be found all over the world, but the precious, coloured opal of Lightning Ridge is exceedingly rare.

And why is it so expensive? Black opal is one of the most enchanting stones in the world, sought after for its seemingly infinite display of colors. Compared to common opal, which is usually one ...

Black opal is one of the rarest gemstones in the world, sought after for its seemingly infinite display of colors, compared to common opal, which is usually one color. High-quality black opal can ...

And why is it so expensive? Black opal is one of the most enchanting stones in the world, sought after for its seemingly infinite display of colors. Compared to common opal, which is usually one ...