Fireworks. Jellyfish. Galaxies. Lightning. Opal’s shifting play of kaleidoscopic colors is unlike any other gem.
Opal is an October birthstone.
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.
WHY WE LOVE THIS GEMSTONE
The novel “Anne of Geierstein” gave opal
a reputation of being unlucky.
Opal contains up to 20% water trapped
in its silica structure.
Grids of silica spheres 0.2 microns in size
create red play-of-color flashes.
When opal formed, silica gel filled crevices in rock. As water evaporates,
the silica is deposited in the form of tiny spheres.
INTERACTION WITH LIGHT
Opal’s flashing play-of-color is caused by diffraction of light
by silica spheres stacked like tiny Ping-Pong balls in a box.
Opal’s arrays of silica spheres form a fantastic variety of patterns and colors.
No two opals are exactly alike.
Play-of-color, intensity, and pattern are important value factors.