Opal
Fireworks. Jellyfish. Galaxies. Lightning. Opal’s shifting play of kaleidoscopic colours is unlike any other gem. Opal’s microscopic arrays of stacked silica spheres diffract light into a blaze of flashing colours. An opal’s colour range and pattern help determine its value.
Birthstones & Anniversaries
Opal is an October birthstone.
Facts
Mineral: Hydrated Silica
Chemistry: SiO2•nH2O
Colour: All colours
Refractive index: 1.37-1.47
Birefringence: None
Specific gravity: 2.15 (+0.08, -0.90)
Mohs Hardness: 5 to 6.5
