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 the Western U.S. — it can also be found in laboratories around the world. Let's talk similarities and differences and pros and cons of synthetic versus natural opals. What's the difference ...

The shinier the pearl, the better. 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 ...