Opal
Opal, the birthstone for October, is valued for its shifting colors in rainbow hues – a phenomenon known as “play-of-color”. Opal’s kaleidoscope of colors is unlike any other gem.
Opal is formed from water drenching dry ground and compressing to for a matrix.
There are two broad classes of Opal: precious
and common. Precious Opal displays play-of-color, common opal does not.
Definition:
The name of this traditional October birthstone is believed to have originated in India (the source of the first opals to the Western world), where in Sanskrit it was called “upala”, meaning “precious stone”. In ancient Rome, this became “opalus” and the Romans believed that it was the most precious and powerful of all gems.
Opal is the product of seasonal rains that drenched dry ground in regions such as Australia’s semi-desert “outback”. The showers soaked deep into ancient underground rock, carrying dissolved silica (a compound of silicon and oxygen) downward. During dry periods, much of the water evaporated, leaving solid deposits of silica in the cracks and between the layers of underground sedimentary rock. The silica deposits formed Opal.
Play-of-color occurs in precious opal because it’s made up of sub-microscopic spheres stacked in a grid-like pattern – like layers of Ping-Pong balls in a box. As the light waves travel between the spheres, the waves diffract, or bend. As they bend, they break up into the colors of the rainbow, called spectral colors. Play-of-color is the result. The colors you see vary with the sizes of the spheres. Spheres that are approximately 0.1 micron (one ten-millionth of a meter) in diameter produce violet. Spheres about 0.2 microns in size produce red. Sizes in between produce the remaining rainbow colors.
Although experts divide the gem opals into many different categories, five of the main types are:
White or Light Opal: Translucent to semi-translucent, with play-of-color against a white or light gray background color, called body color.
Black Opal: Translucent to opaque, with play-of-color against a black or other dark background.
Fire Opal: Transparent to translucent, with brown, yellow, orange, or red body color. This material – which often doesn’t show play-of color – is also known as “Mexican Opal”.
Boulder Opal: Translucent to opaque, with play-of-color against a light to dark background. Fragments of the surrounding rock, called matrix, become part of the finished gem.
Crystal or Water Opal: Transparent to semi-transparent, with a clear background. This type shows exceptional play-of-color.
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The History of Opal:
In 75 AD, the Roman scholar Pliny observed, “Some opali carry such a play within them that they equal the deepest and richest colors of painters. Others . . . simulate the flaming fire of burning Sulphur and even the bright blaze of burning oil.” He marveled that this kaleidoscopic gem encompassed the red of ruby, the green of emerald, the yellow of topaz, the blue of sapphire, and the purple of amethyst.
Many cultures have credited opal with supernatural origins and powers. The October birthstone’s dramatic play-of-color has inspired writers to compare it to fireworks, galaxies and volcanoes. Admirers gave extraordinary opals poetic names like Pandora, Light of the World, and Empress. Bedouins once believed opal held lightning and fell from the sky during thunderstorms. Ancient Greeks thought opals bestowed the gift of prophesy and protection from disease. Europeans long maintained opal to be a symbol of purity, hope, and truth. Hundreds of years ago, opal was believed to embody the virtues and powers of all colored stones.
Symbolism:
Opal is considered the October Birthstone. Some people think it’s unlucky for anyone born in another month to wear an opal. But that particular superstition comes from a novel written in the 1800s (Anne of Geierstein, by Sir Walter Scott), and not from any ancient belief or experience. In fact, throughout most of history, opal has been regarded as the luckiest and most magical of all gems because it can show all colors. Once, it was thought to have the power to preserve the life and color of blond hair.
Opal is a delicate stone with a fine vibration. It enhances cosmic consciousness and induces psychic and mystical visions. Stimulating originality and dynamic creativity, it aids in accessing and expressing one’s true self. Opal is absorbent and reflective. It picks up thoughts and feelings, amplifies them, and returns them to their source. Opal is a protective stone that can make you unnoticeable or invisible.
Psychologically, Opal amplifies traits and brings characteristics to the surface for transformation. Enhancing self-worth, it helps you to understand your full potential.
Mentally, Opal brings lightness and spontaneity. It encourages an interest in the arts.
Emotionally, Opal has always been associated with love and passion, desire and eroticism. It is a seductive stone that intensifies emotional states and releases inhibitions. Wearing Opal is said to bring loyalty, faithfulness and spontaneity, but may amplify fickleness where the propensity is already present.
New South Wales, Australia
Location:
The Opal Birthstone can be found in many places. The fields of Australia are the most productive in the world. Ethiopia, Mexico and Brazil are also important sources. Additional deposits have been found in Central Europe, Honduras, Indonesia, Madagascar, Peru, Turkey and the United States.
Lightning Ridge, a small town in New South Wales, Australia, is famed for producing prized Black Opal. A dry and rocky region softened only by small trees and scrub brush, Lightning Ridge gets little rain and bakes in the scorching summer temperatures. The climate is so unforgiving that miners often live underground to find respite from the punishing heat.
Australia is also a source of many other types of the October birthstone. White Opal is found in the White Cliffs of New South Wales, as well as in Mintabie, Andamooka and Coober Pedy in South Australia. Boulder Opal, which comes from only one location in the world, is mined in Queensland.
In Ethiopia, opal is found near the village of Wegel Tena, in Wollo Province. Travel 340 miles north of the capital Addis Ababa and up 8,000 feet, where miners pry opal from shafts dug into the side of a plateau. Gems unearthed here range in body color from white, yellow, orange and brownish-red to “chocolate” brown. Many of these opals show play-of-color. Another mine, in Ethiopia’s Shewa Province, yields the coveted black opal, as well as orange, white and crystal opal. Its treasures are buried in steep cliffs that tower over the landscape.
Queretero, a state in Mexico, is known for producing fire opal in yellow, orange and reddish orange to red, some with good play-of-color. The mines are a tourist destination, and getting to them requires taking a dirt road through dense forests of pine and oak, past scrubby plateaus of cacti and shrubs, and up winding mountain roads.
Care & Cleaning:
Opal may be treated by impregnation with oil, wax or plastic. Opal doublets or triplets are fine slices of opal glued to a base material and covered with a thin dome of clear quartz. The safest way to clean these October birthstones is with warm, soapy water. Other cleaning methods might damage the opal or filler material. Note that prolonged exposure to water may weaken the adhesive in opal doublets and triplets. Even natural opal can fracture if exposed to high heat or sudden temperature changes.
Opal ranges from 5 to 6.5 on the Mohs Scale of Hardness. To prevent jewelry set with harder gems from scratching opal, store it by itself. Diamonds, Rubies, Sapphires, and Emeralds are just a few of the gems that can scratch this October Birthstone.
Why We Love This Gemstone
Formation:
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.
Unique:
Opal’s arrays of silica spheres form a fantastic variety of patterns and colors. No two opals are exactly the same.
COLOR
Opal’s spectacular play-of-color can display all the colors of the rainbow.
CLARITY
Experts expect different levels
of clarity for different types of opals.
CUT
Fine Opals are often cut into irregular shapes that keep as much play-of-color as possible.
CARAT
Opal has relatively low density so even larger sizes can be comfortable to wear.