15.50 carats Ethiopian Opal Rough - Height: 20 mm - Width: 19 mm- 3.1 g

Excellent natural Ethiopian rough opal. White yellowish base with multicolour fire. Top stone for collectors.
All pictures are taken with a high-resolution camera on dry bone material and on different backgrounds to depict the opal 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 relatively low temperatures and can occur in the fissures of almost any type of rock, most commonly found with limonite, sandstone, rhyolite, marl, and basalt. Only precious opals display a variable interplay of internal colors.
At microscopic scales, precious opal is composed of silica spheres approximately 150 to 300 nm in diameter arranged in a hexagonal or cubic close-packed lattice. These ordered silica spheres produce the internal colors by causing interference and diffraction of light passing through the microstructure of the opal.