Here is an important groundbreaking fact about opals, they are the birthstone of October babies! Are you an October baby? Here is my post about opals from last year, what a difference a year makes!
Opal is a mesmerizing gemstone, it is easy to become lost in the complex play of color of each unique stone. Each opal varies widely in appearance and quality. Each opal is as diverse as a snowflake or a fingerprint.
Writers have compared opals to volcanoes, galaxies, and fireworks. Admirers gave extraordinary opals poetic names like Pandora, Light of the World, and Empress. In ancient Rome, this gem symbolized love and hope. The Romans gave it a name ‘opalus’ that was synonymous with “precious stone”.
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. Arabic legends say it falls from the heavens in flashes of lightning. The ancient Greeks believed opals gave their owners the gift of prophecy and guarded them from disease. Europeans have long considered the gem a symbol of hope, purity, and truth.
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 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.
Opal is known for its unique display of flashing rainbow colors called “play of color”. There are two broad classes of opal: precious and common. Precious opal displays play of color, common opal does not.
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 lightwaves 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 color you see varies 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 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 bodycolor. 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 semitransparent, with a clear background. This type shows exceptional play of color.
Today, roughly 97% of opals come from Australia and of all the opal produced in the world 60% is white opal, 30% is crystal opal, 8% black opal and 2% boulder opal. The town of Coober Pedy, which means “white man in a hole” in Aborigine, produces a major amount of opal, however, the mines in Mintabie and Lightning Ridge produce the rarer, more valuable black opal. The ‘white’ or ‘black’ of an opal refers to the stone’s body color on which the ‘flashes of light and color’ play, with the black offering the most brilliant play of color. Much detail has gone into valuing black opals, even so far as differentiating the seemingly endless types of patterns. The more vivacious and bright the play of color, the more valuable the opal.
There are three main aspects of an opal’s quality:
- Color – Background color and play of color
- Pattern – Arrangement of play of color
- Clarity – Transparency and quantity of inclusions
Here is a brightness and color pattern chart from Opal Auctions for black opal to show the range of pattern and tone.
Irene Neuwirth’s one of a kind necklace with mixed Lightening Ridge opals and fire opals. Photo courtesy of Irene Neuwirth.
Katherine Jetter crystal opal and black diamond stud earrings. Photo courtesy of Katherine Jetter.
Marilyn Cooperman Opal and Tsavorite Bracelet.
Appropriately named the “Mushroom Bracelet”, beautiful Australian black opals are individually bezel set above a sea of bright green tsavorite garnets. Photo courtesy of 1st dibs.
Manuel Bouvier opal and pink sapphire earrings, photo courtesy of Betteridge.
Katherine Jetter’s Birdcage pendant necklace featuring a 365 gram free form boulder opal suspended in a 18k yellow gold birdcage and chain. It is a wonderful specimen of boulder opal, with a combination of the ‘Ironstone’ characteristic of boulder opals and the ‘gemmy’ blues and greens for an opal of its size. The pendant opens at the top, as a miniaudiere would, so the owner can remove the stone and enjoy its’ beauty, holding it as a gem specimen, using it as a paperweight, or simply admire it on its own. The ‘birdcage’ is 18K yellow gold, as are the links of the 32 inch chain. Photo courtesy of 1st dibs.
Opal and diamond earrings, circa 1920.
David Webb boulder opal, colored stone and diamond bracelet. Photo courtesy of Jewels du Jour.
Shreve, Crump & Low Lightening Ridge black opal, blue sapphire and diamond ring. Photo courtesy of 1st dibs.
Nina Runsdorf opal, colored stone and diamond earrings. Photo courtesy of Nina Runsdorf.
Taffin fire opal, moonstone and rose quartz ring. Photo courtesy of Simon Teakle.
Andrea Fohrman turquoise briolette, fire opal and rose cut diamond earrings. Photo courtesy of Andrea Fohrman.
Irene Neuwirth one of a kind boulder opal cuff bracelet. Photo courtesy of Irene Neuwirth.
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