Australian Opal from Coober Pedy - By Dpulitzer - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30411934

Happy October, Fireflies! 

 This month’s birthstone is one of my favorite stones of all time, the Opal!

NebulaThey are, in my opinion, one of the most magical and transfixing stones you could look at. Some say they contain Tiny Galaxies or Nebulas, some say they embody the power of Water Frozen in Time. But most Opals will captivate the attention of both gemstone lovers and the casual observer just the same. They are sparkly, have depth, and reflect tiny rainbows of color to you never once looking exactly the same moment to moment. I could wax on about Opals and how beautiful they are for hours, but it’s not just celebrating my own personal opinions about October’s birthstone what brings us here so read on and come into your own opinions!

Opal Specimine - By Rob Lavinsky, iRocks.com – CC-BY-SA-3.0, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10135016Opals are a member of the Phenomenal Gemstone Family. They are a type of Silica that contains water called Hydrated Amorphous Silica and can actually contain up to about 20% water! Most Opals have closer to 5-10% water in them and can be considered more stable. However in general, Opal is considered quite fragile as they can crack, fissure, and craze easily, and at a Moh’s Hardness of 5-6, they are also considered fairly soft. 

Precious Opal and Potch Opal via The SmithsonianThere are two specimen types of Opals. Precious Opal and Common or “Potch” Opal. Potch Opal is the more abundant of the 2 varieties and is quite a dull stone. The colors range from milky white to dull yellows, reds when containing iron oxides, and even black when carbon or manganese oxides are present. Potch Opals can catch the light and seemingly glow from within, but without the characteristic rainbow of colors Opals are known for, and their luster is known as Opalescence. 

Precious Opal - By Daniel Mekis - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=27929123Precious Opals on the other hand lived a different life and end up in every color of the rainbow! Their vivid and ever changing internal kaleidoscope is known as Play of Color, or Color Play. 

Opal Molecule Spheres - By Dpulitzer - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30686012Opal is formed when water seeps into cracks and fissures in other rocks and brings along with it microscopic spheres of Silica and sometimes other minerals it has picked up in its travels. Over thousands of years the water is slowly and gently evaporated away leaving behind the Silica to settle into an orderly arrangement of molecules, and hardens down into a – mostly – solid mass. When the Silica is settled into an orderly pattern with similarly sized molecules in an undisturbed environment, they act as a defraction grating, and light is defracted into different colors of the rainbow - their color play is fantastic and magical! The larger the Silica spheres, the greater the color range. When the Silica molecules are of different sizes and/or settle unevenly due to disturbance, there is no color-play and you get Potch Opals. 

Where are they from?

Opal Map of the World by Firefly Jewelry Studio

There are many places on this planet where Opal can be found, however today there are 3 major producers. Australia, Ethiopia, Mexico. Honorable mention goes to the USA. 

Australian Opal - Photo by Chip Clark for The SmithsonianAustralia is the chief producer of Precious Opal with deposits being found in South Australia, Queensland, and New South Wales. The Lightning Ridge mine in New South Wales is an especially famous mine, producing the rare black opal with dark gray to black undertones and beautiful color play. The discovery of this Opal field was in 1903 and until that time Black Opal was pretty much unheard of. Black Opals are still the rarest of all the Opals. Coober Pedy in South Australia is known as “The Opal Capital” of the world. Although a very small town itself, after the first opal was found here in 1915, over 70 mining shafts were established, and it became the largest Opal mining area in the world and also the largest producer of Gem Quality Precious Opal in the world. Fun Fact: Coober Pedy is an aboriginal phrase and when translated means literally “White Man in a Hole”. Other mines of note that you may have heard of in Australia are Andamooka, Jundah, Koroit, Mintabie, Quilpie, and Yowah. All produce distinct styles of Opals.

Ethiopian Opal from The SmithsonianEthiopian Opals are quite a bit newer on the scene but have had a major jump in following. Even though Opals were found and used for tools as early as 4000BC, it has only been since 1994 when gem quality Opals were first discovered and used in the gem and jewelry industry, and only since 2004 have the “Wello” or “Welo” Opals coming out Ethiopia’s Wollo Province really stole the show. They are more transparent, have visual depth, and have vivid color play and are very distinct! I personally think they look a bit like magical unicorn rainbow-colored jelly beans…but that might just be me. Of all other Ethiopian Opals, Welos have become the primary Opal sought after from this region. 

Mexican Fire Opals - Photo by Chip Clark from the SmithsonianThis leads us to Precious Mexican Fire Opals. These vivid red, orange, peach and yellow gems might look a little more innocuous, but get them in the sun and that’s when their Fire will come out to play! These lovely beauties can reflect all the color of the rainbow from inside their fiery background color or just a distant flashy glow to be considered Precious. Fire Opals that exhibit less play of color are usually a bit more translucent or even almost opaque, and while they don’t get the distinction of the label Precious, they are still beautiful and desirable. When a Fire Opal grows inside a surrounding matrix of host rock, usually Rhyolite, the opal can be harder to remove, especially when small, and instead they are cut into what is known as Cantera Opals or Dragon’s Eggs! (See below for more information) 

Hungarian-opal from aronstamOther Opal mining spots can be found in South America, Africa, the USA, and Europe, with more notable sources coming from Brazil, Czech Republic, Guatemala, Hungary, Honduras, Indonesia, Madagascar, New Zealand, Nicaragua, Peru, and Slovakia. In fact, up until the 19th century, Slovakia, then a part of the Hungarian Empire, was the primary source of Precious Opal until Opals were discovered in Australia and they took over the main supply. Even the Ancient Romans would source their Opals from Slovakia. 

Lousiana Opal via bestofswlaHere in the United States there are a number of places were different forms of Opal are found which include Arizona, California, Idaho, Louisiana, Nevada, Oregon,and Texas. Each locale has it’s own special form of Opal and can usually be pegged for where it comes from just from appearance. 

At the time of this writing I am developing an Opal Guide to download to help distinguish the types of Opals, where they are from, and what they look like. I will update this blog post when it becomes available. Or, you can get on my email list now and have it sent directly to you when it’s ready! Sign up here!

Other Opal varieties of note: 

Boulder Opal - By Hannes Grobe - Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=3415472Boulder Opal: A type of Opal that forms within a matrix stone called Ironstone. The Ironstone itself can be rather metallic looking and is usually a darker reddish orange or brown and will make the rainbow colors of the opal pop in contrast. They usually come from the Queensland Australia region and have a rabid following. 

Koroite Opal - By Noodle snacks, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=7448299Koroite Opal: A type of Boulder Opal that has a distinct pattern of Ironstone in which the small deposits of opal will settle. The pattern is unique and to me has a squiggly appearance looking like a little flowing river with ripples. 

Yowah Nut via earthstory on tumblrYowah Nuts: Ironstone nodules that contain a pocket of opal. Opalized Ironstone “Nuts” are fairly rare and are quite a treat when cracked open to find the rainbow goodness inside. 

White Opal - via geology.comWhite Opal: The opposite of the Black Opal, the body color of these opals is a translucent to an opaque white color with plenty of play of color, but not as much as the darker cousins which help the colors to pop. They hale from all over the world but most notably the Coober Pedy mine in Australia. 

Cantera Opal or Dragon Egg: Image by Ginger Hansen, Firefly Jewelry StudioCantera Opals or Dragon’s Eggs: As mentioned above, the Cantera Opal can be a Mexican Fire Opal that forms in a surrounding matrix, cut into a cabochon that resembles an egg, and is nicknamed for the fire that seems to be seeping out of the lighter matrix, showing the hot glow of a hatching dragon. However these Opals can come in more than just the fiery colors of Red, Orange, and Yellow. They usually come from Mexico and come in all colors of the rainbow!


Eric The Pliosaur via Altman and Cherny

Opal Fossils: In the same manor that regular opals are formed, in organic matter such as plants, trees, ocean life such as sponges, and even dinosaur bones, the soft tissues are replaced by Silica to form Opal. These Opalized fossils were formed long ago and can take on the texture and grain of the living being before it. Wood grain and cell walls show up surrounded by opal and can be quite stunning! (See Eric The Pliosaur, right)



Peruvian Blue Opal via geology.comPeruvian Opal: An example of Potch Opals at their finest, these Opals are quite a bit different from their Precious fiery cousins. They come in a soft pink and aqua blue and can range from opaque to translucent. They are quite sought after and expensive. 


As mentioned earlier, Opals are considered to be a fragile stone. They grew from water and sometimes can be very thin having formed in small cracks and crevices, and even still contain some residual water and thus should never get wet (so taking off your Opal rings when washing your hands is a must) and can easily fracture, chip or craze - similar to cracking but where the Opal stays together but many tiny cracks begin to form and spread through the stone like a net - if bumped, jostled, submerged in water, or sometimes just looked at wrong. Over time people have developed ways to stabilize and secure their Opal pieces. 

Opal Treatments via Firefly Jewelry Studio


Doublets: A piece of Opal is secured to a stronger material on the back such as Ironstone to give the piece some thickness and strength. Potch Opal is used quite often and also Ironstone is used frequently since Opals naturally grow with it. Boulder Opals can be thought of as a natural doublet since the Ironstone and Opal grew together, and are considered stronger for it.

Triplets:  A piece of Opal is secured on the back the same as a doublet, but then a piece of clear Quartz, glass, or similar gemstone is secured on top of the Opal forming 3 layers. This is the most secure an Opal can be however the process is usually used on very thin pieces of Opal and the value of the piece itself is quite a bit lower than a natural Opal or a Doublet. These are great pieces to use on rings where you need more strength and for a more cost effective option.

*At Firefly, Doublets and Triplets are acceptable forms of treatment as long as it is fully disclosed, since the actual Opal being used isn’t altered, only protected. However I prefer to stop at the use of Doublets since you can still feel the gemstone with your fingers and the Triplets you cannot.

The following treatments are not acceptable in Firefly’s jewelry collections:

Big no-noSugar Treating or Smoke Treating: These treatments change the actual surface of the Opal, making it darker and look more like a Black Opal. Sugar Treating involved soaking the Opal in Sugar and then Sulfuric Acid to darken the surface, and Smoke treating involves wrapping the Opal in paper and “Smoking” it. Both of these treatments leaves carbon residue on the surface and in pits reaching below the surface. Opals are porous and the treatment can reach below the surfaces to a certain extent but if the stone is chipped it will show its true color – which will be lighter. Smoke Treatment is most often used on Ethiopian Welo Opals, and Sugar Treated Opals are called Andamooka Opals. And while that can sound quite fancy, it is still a treated Opal. 

Opal Peacock Brooch by Harry Winston via The SmithsonianSome gemstones, such as Emeralds and Sapphires are treated so often that as a consumer you should always expect that they have been treated some way unless coming with certification that they have NOT. Opals on the other hand don’t need to be treated and I prefer to use them in their natural states, and I always disclose any known treatments to my customers. (Check out this beautiful untreated Australian Black Opal Peacock Brooch by Harry Winston. The Opal is from Lightning Ridge and also sports Diamonds, Rubies and Sapphires! For more information on these gemstones, click on the preceding respective links. Drool....)

Synthetics and Imitations:

Synthetic Opal via Denver Gem CuttingAs with many gemstones out there, Opals have been imitated in a lab for quite awhile now. They too can come with fancy names such as Gilson Opals, Opalite, and Slocum Stone. The synthetics can be quite convincing at first but upon closer inspection they will reveal themselves. (And who doesn’t love to stare deeply into an Opal searching for the answers of the Universe?? If you look, you will see the signs of real vs. fake though) Synthetics can usually display one of two major signs. Gilson Opals (see image to the left) display a pattern called chicken wire or snakeskin which can be a tell-tale sign that your opals are not natural. It is a mosaic like pattern that looks like scales, and from the side looks like little columns. Some imitation Opals like Slocum Stone are made with thin pieces of metallic foil suspended in glass. The flakes of foil look obvious once you notice that they don’t have a true play of color. Still, it is best to source your Opals from a trusted dealer and educate yourself on what the fakes look like so you are not taken for a ride. Opalite Glass (below) is simply glass that has a yellow and bluish milky appearance to it. (There is a natural Opalite that comes out of the USA but it is opaque, silky green and quite distinctly NOT Opalite Glass) 


Firefly Jewelry Studio is careful to source directly from trusted cutters and the mines where the gemstones come from. I only use natural Opals and as I mentioned earlier, the most treatment I will use is a Doublet since these are still natural Opals that have simply been strengthened from the back to add durability yet you can still feel and touch your beautiful Opal with your bare hands.  


ChakrasOpals are most well-known to magnify your own traits and characteristics. This can help one to address any issues with such attributes should any be seen as less than positive and holding one back, with self-love and understanding. Opals are also very well known to help one recognize and harness the creativity and inspiration that lies within each of us! One source states that Opals are the "stone of happy dreams and changes" meaning that the recognition of your inner self, creativity, and potentials can foster change towards bettering your life through beautiful change from within. Opals have been used to awaken psychic abilities and harness the mysticism of intuition and insight, gifts of which can push one towards greater understanding of one’s self both in the physical and sacred forms of being. Black Opals are a stone of truth and protection.  


Famous Opals


The Olympic Australis

The Olympic Australis Opal

Photo courtesy of Altmann & Cherny Ltd.


Found in 1956 in Coober Pedy Australia, it is valued at $2.5 million and is the most expensive Opal in the world. It was named for the Olympic Games which happened to be held in Melbourne at the time it was found. It weighs 17,000 carats and is 99% Precious Gem Opal. It is kept in Sydney at the Opal Specialist’s Offices of Altmann & Cherny Ltd.

The Aurora Australis

 The Aurora Australis Opal

Photo Courtesy of Seda Gems

This beauty is the world’s most valuable Black Opal. Found in 1938 in a sea bed in Lighting Ridge Australia, this stunner weighs 180 carats and was valued at over $700,000 USD ($1million AUS). It gets its name for its vivid color-play resembling the Southern Lights and is said to have a distinct Star Fish impression on the back.

The Andamooka Opal or Queen’s Opal

 The Andamooka Opal or Queen Opal

Photo courtesy of Altmann & Cherny Ltd.

 Altmann + Cherny bring us another beauty, this time in the form of a finished piece of jewelry fit for a Queen. In 1954 the South Australian Government wanted to honor Queen Elizabeth II with a gift and chose the finest Gem Opal from the Andamooka Mine to cut and set into a suite of a necklace, earrings, and cufflinks to be presented to the Queen and Prince Philip during their tour there. The necklace is in the crown jewels and has been on display at Buckingham Palace.







The Black Prince

The Black Prince Opal

Photo courtesy of Altmann & Cherny Ltd.

This 181 carat beauty was found at the Phone Line patch and was originally a part of a set of 4 notable Opals from the area. This black opal plus 'Black Prince', 'Pride of Australia' and 'Empress' were bought for £2000 ($2629 USD today) in about 1920. At the time this was the most ever paid for four black opals. The colors on the Opal are rich and deep and on one side are black, green and blue and display a flag pattern, but the other side is red. This Opal a long history of owners but was finally stolen from the Forest Lawn Cemetery, Lost Angeles with several other beautiful Opals in the collection.

The Pride of Australia

The Pride of Australia Opal
Photo courtesy of Altmann & Cherny Ltd.


Also known as the Red Emperor, this 225 carat Opal was found in 1915 in the Phone Line Patch and was shaped like Australia. It was 2x3” and was on tour with the World’s Fair until 1954 as “The Greatest Opal in the World”. The markings on it were distinct. Black outlines with bright red patches and blue veins. To this day the final price paid can’t be agreed upon but some say it  was between £50,000 and £150,000 ($65,730 to $197,187 USD today) It was later stolen with the Black Prince and the Empress from Forest Lawn Cemetery, Los Angeles

The Flame

The Flame Opal

Photo courtesy of Altmann & Cherny Ltd.


When this beauty was found the miners knocked on a large “nobby” opal to crack it and see inside, they were stunned to find a brilliant red dome surrounded by a blue and green circle. It was nicknamed the Poached Egg. They were starving so they sold it for only £97 but according to opalsdownunder.au, “The asking price for this unusual opal has continued to climb over the years with each change of hands. In 1925, an offer of £2000 was made. In 1948, the stone was valued at £5000. In 1973, $US 32,000 was paid. In 1980, 'Flame' was for sale again at a million dollars! As of 1992, the stone was back home in Australia. In 2003, 'Flame' was put up for auction at Christie's in New York but was passed in for an undisclosed reserve. (Estimated at US$250,000) Current photos confirm the beauty of this gem and no sign of crazing after 86 years of to-ing and fro-ing. A Brisbane jeweller submitted the stone to the Queensland Geological Survey. It was established that traces of ginko, a fossil plant (Chinese maiden hair fern), occurring in Jurassic rocks but not in any opal deposits, were impressed on the back of the gem.”


I hope you’ve enjoyed this round of gemstone trivia! Opals are one of my favorites stones and worth so much more time than was can be given here in this little blog. Make sure to check out the Opal pieces I have in my collections and as always, if I can help you in any way by creating an Opal piece for you that will make your dreams come true or if you have an questions for me, please don’t hesitate to contact me! I’d love to hear from you!

Australian Black Opal Mystic Waters Earring Studs by Firefly Jewelry Studio  Ethiopian Opal Ring by Firefly Jewelry Studio  Australian Black Opal Twinkle Necklace by Firefly Jewelry Studio

Happy October, everyone! Get outside and enjoy that beautiful Fall weather and all the colors!

With love,





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Excelente información y extraordinarias imágenes.
Gracias por compartir el tema.
Estaré muy agradecido si me comparten información cada vez que ocurra una actualización!

Reciban un cordial saludo!
Desde la Ciudad de México!


Thanks, Barb! Glad you enjoyed it!


Good job, Ginger!

Barb Jacobson

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