Take one look at any opal and you’ll find a world of colors illuminating from the gem. Opals are renowned for an optical feature called “play-of-color,” which describes the way color dances across the stone. No opal stone displays just one color, so what is the most common opal? To answer that, we have to look at the body color (body tone) of the gem. Based on body tone, white opal is the most common opal color, followed by gray opal and green opal.
If you hear “common” and think “ordinary,” we’d like to ask you to think again! You could call this gem a master of disguise for the array of opal colors out there. Opal can’t be concealed though; its glimmer and enchanting play-of-color are sure to catch anyone’s eye!
Speaking of eyes, one theory of opal’s etymology is from the Greek word for eyes, ophthalmos. Another possible source is the Sanskrit word Uppal, which means “precious milky stone.”
October babies might recognize the gorgeous milky opal as the traditional October birthstone. If you were born in April, you can honor the ancient mystical birthstones with some gorgeous opal jewelry of your own.
No matter who flaunts it, opal is an enchanting gem with lots of charm. To fully understand the most common opal color, we’ll need to dive into the different types of opals and where they come from.
First, let’s go over the basics.
Opal is a mineraloid composed of silicon dioxide and varying amounts of water. Unlike most gemstones, opal doesn’t have a crystal structure or consistent chemical composition, making it amorphous.
Opal belongs to its own gemstone family, the opal family. Opal gems get their trademark pearly sheen from their internal structure, made up of tightly packed spheres that split up the light into multiple colors.
So, what color is opal?
You may associate opal with colorful iridescence, reminiscent of the rainbows on soap bubbles. However, iridescence is specific to precious opal.
Precious opal, or noble opal, is a variety that displays play-of-color. In other words, turning the stone under the light will cause the gem to shine in an array of colors. The colors will change depending on the angle you view the gem.
Precious opal colors vary from stone to stone. Some precious opal stones may have a dark base, such as black or royal blue. Others could have a white body tone. Some precious opals show so many different colors, the base color is indiscernible.
Precious opal often gets confused with the variety called “common opal,” which we’ll explore in greater detail next.
Common opal, or “potch,” is the most abundant variety of opal worldwide. The gem comes in a wide array of colors and most opal varieties fall under the “common opal” umbrella. How can you identify common opal? If the stone doesn’t exhibit play-of-color, then it’s good ol’ fashioned common opal.
Another signature trait of common opal is opalescence. Opalescence is an optical effect that describes common opal’s milky, internal glow. While the play-of-color effect makes a gem’s surface reflect light, opalescence looks like a hazy light coming from inside the stone.
Common opal can show almost any color, and its pastel hues are adored by many. Most often, common opal has a white or blue body tone.
What is the rarest opal color? The rarest opal specimens have a red or black body tone.
A black body tone is great for displaying another fascinating opal trait: fluorescence.
Have you ever cracked a glow stick? That green glow you see afterward is because of fluorescence. Opal can show fluorescence weakly or strongly, even in the same green color of a glow stick. An opal can also fluoresce in yellowish-green, light blue, greenish-brown, or white.
The cause of opal’s fluorescence is most likely hints of uranium inside the gem. More uranium can cause stronger fluorescence. Some fluorescent opals from Nevada have 0.12% uranium by weight!
We know where opal’s fluorescence comes from, but what about its color?
Common and precious opal form in mostly the same environments: deep within rocks in areas with an arid climate. Miners may have to dig 60 feet underground to find opal worth selling. Why so deep? Well, opal formation happens over millions of years.
First, hot water soaks into the ground. As it flows down into the earth, the water collects silica spheres. Eventually, the silica-rich water settles into pockets in the rock. The silica spheres get packed together as the water evaporates, leaving behind colorful opal.
Where does opal color come in? It all goes back to the silica spheres.
The silica spheres in opal are technically silicon dioxide crystals. When the spheres are around the same size and packed in neatly arranged stacks, we see play-of-color. Isn’t nature amazing? The size of each sphere determines which color of light that area reflects.
If you’ve been following along, you might’ve realized that only precious opals have tightly packed spheres. If so, A+ to you!
Common opal’s silica spheres are disorganized and vary a lot in size. Therefore, common opal cannot reflect the spectrum of light that precious opal can. Instead, common opal can only display a limited color range, determined by the size and distance between its spheres.
On the topic of distance, how does hunting for opals sound? Next, we’ll break down all the opal hotspots worldwide so you can plan your next opal odyssey!
Although opal can be found in various rocks and locations, specific environments produce different opal colors. Some locations are known for their opal varieties.
One town called Coober Pedy in South Australia is known as the “opal capital of the world.” Australia is so renowned for its opals, opal is the country’s national gem!
Australia boasts some of the most abundant opal deposits in the world. In fact, at least 90% of the world’s opals come from Australia!
Each opal-producing state in Australia has an opal color specialty.
In the fields of Western Australia, pink opal is common. “pink opal” is actually a trade name for Mookaite with opal attached to it. However, opaline Mookaite can show patterns in shades of cream, yellow, and red.
Another opaline stone is the boulder opal.
Found in Queensland, boulder opal is a combination of opal and ironstone. Each boulder opal has unique coloring and patterns. In general, boulder opal is brown with a scattering of luminescent purples, blues, or greens.
The exclusive black opal color is the specialty of New South Wales.
Black opal is incredibly hard to come by. The lucky few who can get a black opal might get lost in its mesmerizing brilliance and color patterns.
Lastly, South Australia specializes in light opal. Light opal is typically white or cream, giving the stone the nickname “white opal” or “milky opal.”
Australian Black Opal
Ethiopia and Kenya have made quite a splash in the opal market.
Australia is the king of opals, but Ethiopia has been competing for the crown.
Ethiopian opals are mostly white and cream precious opals. In recent years, the coveted black opal color has shown up in Ethiopian deposits as well.
The Ethiopian Welo opal is another stunning local variety. Named after the Wollo Province, Welo opal is a precious fire opal with red, orange, and yellow body colors. Welo opals can display vibrant green or purple color flashes.
Kenya plays a significant role in opal’s history as the location of the oldest opals ever discovered. In modern times, common opal is Kenya’s most abundant variety. What color are they? Kenya’s opal colors consist of beautiful shades of olive green.
Ethiopian Welo Opal
Over in South America, Peru and Brazil are the continent’s key opal suppliers.
If you’re a fan of the pastel color palette, you’ll love Peru’s opal collection. Peruvian opals come in an array of soft pastels, particularly pink, blue, and green.
Brazilian opal is unique in its durability and brilliance. Brazil’s crystal opal displays play-of-color in mystical pastel tones. The low amount of water in these gems gives them better durability, so jewelers can bring out the best opal colors with a variety of faceting techniques.
Mexico takes pride in two unique opal colors: the Mexican fire opal and the Morado opal.
While many opals are translucent to opaque, Mexican opal colors display a transparent to translucent surface.
Mexican fire opal color is, perhaps unsurprisingly, similar to fire. The gem can be yellow, white, orange, or red. Like a burning flame, the best specimens have a saturated red-orange color.
The Morado opal is a purple opal color variety. Morado means “purple” in Spanish, hence its moniker. These opals are typically opaque with a milky lavender and violet color pattern.
Mexican Fire Opal
American opal mines are spread throughout the country, but two notable states for opal production are Oregon and Nevada.
Oregon. Oregon has two significant opal mines: one in an area aptly named Opal Butte and one in Lake County. Oregon’s opals mostly consist of pink, yellow, and blue shades.
The volcanic ashfall in the state creates a great environment for opalized wood to occur. Opalized wood is petrified wood that contains opal inside instead of the more common chalcedony.
Opalized wood forms when ashfall creates a protective forest layer, allowing for the ash’s dissolved silica to seep into the ground. From there, groundwater sources can collect the silica and begin the usual opal formation process.
Nevada. The locals of Virgin Valley, Nevada, claim that opal started forming there millions of years ago. Opalized fossils may give this theory some weight, but no one can be certain when the opal formed onto the fossils.
Regardless, Virgin Valley opals emerge from wet clay beds in spectacular colors. Nevada’s opals include black opal and precious black opal, for starters. Other opals mined include white and yellow opals, plus opals with moss or dendrite inclusions.
The area’s high uranium levels give many opals high fluorescence. Under an ultraviolet lamp (or blacklight) these opals glow bright, electric green.
Virgin Valley American Opal
With all the opal color options out there, you might wonder: What are the best opals to buy?
Determining an opal’s value isn’t a simple process. Numerous factors affect an opal’s overall value, from where it was mined to what shape it takes, and of course, its unique color properties.
Generally speaking though, the most valuable opals are the rarest varieties and the least valuable opals are the most common.
So, what color opal is most valuable?
Black opals are the rarest variety of opal, with precious black opal being even harder to find. However, the highest-valued common opal color is the rare red opal. Orange, green, blue, and purple opals are next in line in terms of value.
If you’re curious, the most expensive opal in the world is The Virgin Rainbow (pictured below). Discovered in 2003, The Virgin Rainbow’s value exceeds $1 million. The impressive specimen is currently on display in the South Australian Museum.
If you’re ready to pack a bag and plan an opal expedition, we don’t blame you! Opal is a one-of-a-kind gem, but each opal is unique!
With all this knowledge under your belt, you’re set to impress. Why not ditch the “What’s your favorite color?” line for “What’s your favorite opal color?”
Don’t worry, there are plenty of opal colors to go around!
Have you chosen a favorite? Find the perfect opal color for you!
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