66.0 carats Australian Rough Opal Rough- 13.2 g

Natural Australian Rough Opals.
Dimensions from approximately 9 to 25 mm.
Please note that the photos were taken on both dry and wet opal. Clearly, the wet opal appears brighter and more colorful, emphasizing the effect that can be achieved after polishing. In Australian mining practice, rough opal is traditionally photographed wet to showcase the stone's potential. Therefore, we encourage you to carefully evaluate the photographs before bidding. Thank you for your attention, and happy bidding!


An opal is a hydrated form of silica with a water content ranging from 3 to 21%. Furthermore, 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. 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.