Rarest and most prized among all opals is Black Opal, an opulent and stunning variety found in Lighting Ridge / N.S.W. Australia. Also the most valuable of opals, Black opal is characterized by black potch (ie dark common opal beneath opal with play of color. This layering of polished opal over the dark potch creates a gorgeous depth of color in the stone. Colors can include the entire spectrum with red being the rarest and considerably more coveted color.
Named for the iron clay host stone that enhances the opal, Boulder Opal is mined in Queensland, Australia. To give the opal both strength and color, the host stone is cut in union with the opal. The entire spectrum can also be found in Boulder opal with prevalent colors often blue/greens, purples and reds.
Found in and around the town of Yowah, Australia, Yowah Opal is a variety of boulder opal. It is sometimes referred to as a “Yowah Nut Opal” because it is found as a geode-like rock containing an opal center. Very rare and desirable, these opals can have beautifully unique patterns from the interaction between the opal and rock when the Yowah is formed.