White Opal Jewelry - Artisan and Artist CraftedWhere the name comes from: Sanskrit upala meaning jewel.
Where the stones come from: 97% of the world's supply comes from Australia with South Australia providing 80%.
Chemistry: Silica, SiO2 - with a relatively high water content of 6-10% typically.
Colors: All colours, the internal structure of opals make them diffract light so causing a play of colors with the movement of the stone, greens and blues are most common with red being the rarest. White refers to the base color.
...and another thing: Pattern and brilliance are the main factors in deciding the value of an opal rather than its color.