Opal

Opal 
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Distinguished for its play-of-color, opal displays a brilliant range of rainbow-like colors when seen from different angles.
Opal was once considered a symbol of fidelity, assurance, and religious devotion.
The ancient Roman historian, Pliny the Elder, suggested the opal is difficult to describe because it blends so many colors in a “brightness that is incredible.”
Australia is the primary source of Opal.
Opal is the birthstone for October.