Black Opal JewelryWhere 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. Black refers to the base color against which the diffracted colors are best seen.
...and another thing: Black Opals are the rarest and considered to be the most beautiful form.