ABOUT OPAL

ABOUT OPAL

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Because opal has the colors of other gems, the Romans thought it was the most precious and powerful of all. The Bedouins believed that opals contained lightning and fell from the sky during thunderstorms. When Australia’s mines began to produce opals commercially in the 1890s, it quickly became the world’s primary source for this October birthstone.

BIRTHSTONES & ANNIVERSARIES

Opal is an October birthstone.

0.2 MICRONS

Grids of silica spheres 0.2 microns in size create red play-of-color flashes.

20% WATER

Opal contains up to 20% water trapped in its silica structure.
 

1829

The novel “Anne of Geierstein” gave opal a reputation of being unlucky.

FACTS

• MINERAL: Hydrated Silica
• CHEMISTRY: SiO₂•nH₂O
• COLOR: All colors
• REFRACTIVE INDEX: 1.37-1.47
• BIREFRINGENCE: None
• SPECIFIC GRAVITY: 2.15 (+0.08, -0.90)
• MOHS HARDNESS: 5 to 6.5