Opal - The October Birthstone
Imagine all the colors of the rainbow, scattered across the
constellations, set against a background which is sometimes ebony,
sometimes sky-blue, or even milky-white, illuminated by flashes of
lightning. Legend has it that such a gemstone fell from the heavens in a
flash of lightning. October’s birthstone derives its name from the
Latin word ‘opalus’, which means precious jewel. The Romans called it
‘Cupid Paederos’, meaning a child as beautiful as love.
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When viewed from different angles, precious opals radiate various
colors. Opals can be either translucent or transparent, with a light or
dark body color, light being the most common. Black opals are the most
rare and expensive, with a body color that can range from dark gray to
black with fiery flashes of color. Precious fire opals have base colors
ranging from yellow to orange, and can be transparent to translucent
with fiery flashes.
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Opals radiating fire and energy were prized by the royalty of yore
for their perceived protective powers as well as their beauty. Ancient
monarchs wore these gemstones in their crowns and necklaces to ward off
evil and protect the eyesight. Opals were believed to have healing
properties as well as the ability to keep nightmares at bay, so they
were also ground and ingested.
The opal’s unique ability to refract and reflect specific wavelengths
of light and color comes from silica spheres within this gemstone. The
opal is formed from non-crystallized silica, a mineral found near the
earth’s surface. As ancient geothermal hot springs dried up, layers of
the silica, combined with water, were deposited into the cracks and
cavities of the bedrock, producing opal. Water constitutes up to 30% of
an opal, so the opal must be protected from heat or harsh chemicals,
both of which will cause drying and may lead to cracking and loss of
iridescence. As it is relatively soft and breaks easily, it must be
protected from blows.
Harsh cleansers and ultrasonic cleaners are never to be used on
opals. Oil should not be rubbed on an opal either, even though it makes
the opal seem more fiery, because it can damage the opal. Some jewelers
recommend periodically soaking opals in water to help them reabsorb lost
moisture.
Southern Australia is the source of most of the world’s opal
deposits. Other sources of this gemstone are Brazil, Mexico,
Czechoslovakia, Nevada in the United States, areas of the former Soviet
Union, Africa and Nicaragua. Many fire opals are found in Mexico.
A gift of an opal symbolizes faithfulness and confidence. Watch out
for opal doublets and triplets, composite stones made by positioning a
thin layer of opal on top of a chunk of glass or less expensive
gemstone. Scrutinizing the sides of an ‘opal’, looking for tell-tale
signs of a stack of layers, will help you uncover a composite opal. If
the stone’s base doesn’t match the top, it might also be a composite.
