No Reserve - Ct. 8.70 Natural Ethiopian Black Opals - Oval Cabochon - Height: 7 mm - Width: 5 mm- 1.74 g

Beautiful Parcel of Natural Black Ethiopian Cabochon Opals from Wello, Ethiopia.
Clarity: from transparent to opaque;
Dimensions: 7 X 5 X 3 mm;
Treatment: smoked.
Pictures taken with high resolution camera on different backgrounds in order to depict the opals as realistically as possible.
Worldwide shipping with registered mail and tracking number.

An opal is a hydrated form of silica with a water content ranging from 3 to 21%. Indeed, it is this permeability to water that makes it a hydrophile.
Opals are deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt. Only precious opals show a variable interplay of internal colors.
At microscopic scales, precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic close-packed lattice. These ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal.