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The October Birthstone

Learn more about the kaleidoscopic gemstone associated with October: the opal
Opals hero

The idea of a different gemstone representing each month of the year dates back to Biblical times. The Jewish historian Josephus made a record of Aaron from the Book of Exodus wearing a breastplate decorated by twelve stones all the way back in the first century. We will be exploring the properties and traditions of each stone monthly on Facet. For October, the American Gem Society's stone is the lovely OPAL, a stone that reflects almost any color of the rainbow.

If you missed our previous birthstone articles, click here to learn more about the September sapphire and some of the famous women who wore them. Want to read our piece about peridots and sardonyx, the stones associated with August? Check it out here!

Opal 1
Opal 2

Opals are mentioned throughout prehistory, but were only discovered in large deposits in Australia around 1850. Today, more than 90 percent of the world's commercial opals are mined there. They are also found in Mexico, Brazil, Honduras, Ethiopia, and the Czech Republic. The only places in the U.S. where opals have been found are Nevada and Idaho. 

Opals are formed from silica deposits from the rain finding their way into the cracks and fissures in between layers of rock. As the silica seeps into places and the water evaporates, opal deposits are formed. The percentage of water to silicon dioxide in a deposit can determine the color of the stone and the way it refracts the light. The silica forms into spherical shapes, and those spheres can reflect light to represent almost any color of the rainbow. The result is the lovely, kaleidoscope-like look of an opal. 

The very word "opal" comes from the Greek opallios, which translates to “to see a change in color.” 

There are dozens of varieties of opal, determined by what type of rock the silica settles in and the ratios of silica to water. The best-known varieties are the Boulder Opal and the Fire Opal, both commonly-used in jewelry. Opal is a delicate stone, only measuring 5.5 to 6 on the Mohs scale. They are easily cracked or scratched and can be damaged by extreme changed in temperature. 

Opals are valued by the range of color in the stone. Most have either a white or black background color, and then a layer of more brightly-colored iridescence, called the "play of color." Black backgrounds are more highly-prized, and the brighter the color palette, the better!

For a period of history, opals were considered unlucky or possessing the power of evil. The stone's bad reputation was largely attributed to a novel written by Sir Walter Scott in 1829. It was also thought that the stone could convey the power of invisibility if it were wrapped in a bay leaf!

But today the superstition has shifted and opals are highly prized. There is an Australian legend about opals governing both the stars and true love. The stone is also said to repel evil and protect eyesight -- but only when set in a necklace!

Opals are frequently irregular in shape, due to their nature of forming in irregular crevasses of rock. They are mainly available as cabochons, also some (mostly chips) are also drilled as beads. Very popular as the October birthstone, opals in the white color family can be very budget-friendly!

Here's a sampling of the projects on Facet perfect for the October birthday! 

Blue opal briolettes hero
A strand of briolettes requires little embellishment to look striking. To create the Blue Opal briolettes necklace, string a few tiny bronze Charlottes to space the briolettes and to accent their brown tones. Or, try silver-colored seed beads for a more modern look. 
October Opal earrings
No, these October birthstone earrings are not real opals, but tumbled glass has a beautiful translucent sheen; its near-opalescence makes it a good substitute for opal. The pendants in these earrings are affordable and available in a range of colors, so you’ll have lots of seasonal choices. 
October birthstone Opal chip bracelet
Because stone-cutting decreases an opal’s weight, rounds and rondelles are becoming pricey and harder to come by. For a budget-friendly option, this Opal chip bracelet uses opal chips, which are readily available and less expensive. Pair them with amazonite to highlight extra color.
October birthstone Opal necklace
Not all opals are the same familiar bluish-green color! This Birthstone necklace features paler stones that look stunning when paired with gold-toned chain and vermeil disc charms.