The word opal comes from the Greek 'opallos', which means ' color change', alluding to the shade of the opal which appears to fluctuate when tilted under light. This marvel happens because of an inward diffraction of light which scatters a range of gleaming hues. The opal family is very well known for its extraordinary rainbow shading play, and is accessible in a relatively limitless exhibit of shades including white, black, yellow, rosy, green, blue, colorless and multi-hued. The opal has a normal hardness of 5.5-6 on the Mohs scale. A horde of superstitious legends exist with respect to the roots of opals and the otherworldly powers that these stones may have. It primarily originates from Australia, with Mexico and the United States filling in as its optional sources. Opal is the October birthstone in the US.