Opals are magical, with a "play-of-color" that flashes rainbow fire unlike any other gemstone. As your guide from Juyoyo, where gemstone expertise meets practical buying advice, I'll cut through the confusion. While they may look similar in photos, Australian and Ethiopian opals are actually very different. Australian opal is a durable, stable, classic choice, while Ethiopian opal is the brilliant, beautiful, and affordable newcomer.
Before we compare them, let's establish a clear understanding of these two types of opal. Both are "precious opals" renowned for their spectacular play of color.
To help you understand some of their differences so that you can decide which type of Opal best suits you, in this article, we’re going to compare Australian Opals to Ethiopian Opals.
Enticed by the mesmerizing iridescence of an opal? Us, too! If your opal search has landed you in a pickle where you can’t decide between Australian Opal and Ethiopian Opal, it helps to know the key differences.
Origin and Formation
Australian Opal
Australian opal is a sedimentary opal. It formed over countless millennia (65 to 140 million years ago) when a silica solution seeped into the cracks and fissures of ancient Cretaceous rock. As the water evaporated very slowly, silica particles were left behind and stacked in near-perfect spheres.
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It’s mined from deep beneath the earth’s surface. Because Australia was millions of years ago covered in geothermal water, there’s water deep in the ground where opals grow, and that water is precisely what shapes the physical and chemical properties of Australian opal.
Australia has been the world’s largest supplier of opals for over a century, with iconic mining areas such as Coober Pedy, Lightning Ridge, and Boulder Opal fields.
Ethiopian Opal
Ethiopian opal is a type of volcanic opal. It formed more recently within nodules of volcanic rock (rhyolite). Silica-rich hydrothermal fluids flowed through the rock, depositing opal in nodules and seams.
Whereas Australian opal is mined from deep beneath the ground, Ethiopian opal grows in large volcanic deposits high up in the hills.
Ethiopian opals are newer to the market, discovered in the 1990s, and primarily mined in the Wollo and Shewa regions.
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Significant deposits were discovered there in the 1990s and 2000s. It is primarily sourced from the Welo (or Wollo) region in the Ethiopian highlands.
How to tell a fake opal or Synthetic opal from the real thing by www.blackopaldirect.com
Core Identity and Characteristics
Australian Opal
- Core Identity: Australian opal is synonymous with stability, depth of color, and heritage.
- Australian opal comes in a wide range of types and colors.
- Among them you’ll find Boulder Opals, Pipe Opals, Crystal Opals and Black Opals - some of these types even have some crossover.
- It’s not easy to summarize the color of Australian Opals because they capture all colors.
- An extensive array of patterns can be found in Australian Opals.
- Australian opals are non-hydrophane. This means their structure does not absorb water. Consequently, they are highly stable and resistant to environmental changes. They are also far less prone to cracking.
Ethiopian Opal
- Core Identity: Ethiopian opal is characterized by its often breathtaking brightness. It is also known for its high transparency. The play-of-color patterns are remarkable.
- Ethiopian Opals will also cast back a spectrum of hues, however they commonly have very recognizable base tones ranging from earthy browns and oranges to yellows, and sometimes white. These gems often appear somewhat jelly-like, flashing holographic rainbows from their crystal-like bases.
- Over the years, Ethiopian Opals, with their assortment of patterns, have assumed a similar naming system to that of Australians.
- Ethiopian opal is hydrophane. Think of them as delicate sponges that can absorb and release water.
Play of Color
Australian Opal
The colors in Australian opals often appear to emanate from deep within the stone. Against a dark body tone, such as black opal, the colors-reds, greens, blues, and violets-appear profoundly saturated and luminous. The effect is one of solidity, depth, and a mysterious internal fire.
This black opal has a lot of red play-of-color, which is considered highly desirable.
The contrast of play-of-color to bodycolor makes black opals very popular.
In general, connoisseurs prefer large, closely arranged patches of color over tiny, scattered dots.
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The harlequin pattern in this black opal has a lot of red, blue, and green play-of-color.
Ethiopian Opal
They are renowned for their bright, often large-patterned play of color that appears to dance on the surface. Their high transparency creates a crystal-clear or "jelly"-like background that makes the colors appear exceptionally bright and fiery.
Play-of-color might be the most spectacular aspect of an opal’s appearance. No matter the color or combination of colors, play-of-color must be vivid to command a high rating. Secondary in importance to play-of-color’s strength is its range.
If an opal’s play-of-color is not just bright, but also ranges across the entire spectrum, it’s very rare and valuable.
Pattern describes the arrangement of an opal’s play-of-color.
Hydrophane Nature and Stability
Perhaps the most significant difference between Australian Opals and Ethiopian Opals is that most Ethiopian Opals are hydrophane while Australian Opals are not. What does that mean? It means that Ethiopian Opals are hydrophilic (water-loving) and they will readily and readily absorb water.
Ethiopian Opal
Sudden changes in moisture (like moving from a steamy bathroom to a dry, air-conditioned room) can cause stress, leading to "crazing"-a network of tiny cracks.
When Ethiopian Opals absorb water, the stones will typically lose their color. This should be a temporary shift in state that should resolve after a period of drying out - sometimes up to two weeks - and then the stone’s color should return. And sometimes, this is the case.
However, here at NIXIN Jewelry, we have also worked with Ethiopian Opals that have been exposed to water, lose their color, and after a drying period, their original color has not returned.
In addition, we have also seen their crystal base permanently turn cloudy or transform an entirely different color - ie: from white to orange.
Moreover, we have also seen Clients experience permanent color change with Ethiopian Opals in cases where they haven’t exposed their jewelry to water.
It is most likely that something else permeates through the porous surface of the Opal, such as lotion, natural body oils, perfume or perhaps something else entirely, that alters these otherwise beautiful stones.
Australian Opal
Australian opals are non-hydrophane. This means their structure does not absorb water. Consequently, they are highly stable and resistant to environmental changes. They are also far less prone to cracking.
You still need to be careful. Don't wear it to the gym or while gardening. But it can handle the rigors of everyday life.
Treatments
An Australian black opal from Lightning Ridge is 100% natural. In contrast, a "black Ethiopian opal" is almost always a treated gemstone. These are not the same gem.
While there is the occasional unearthing of Ethiopian Black Opal, some Ethiopian Opals are treated with smoke, dyes or a sugar-acid in order to achieve a darker or more vibrant appearance.
Always Ask About Treatments: Ask the seller, "Is this opal natural and untreated?
Price and Market
This is the main reason Ethiopian opals are so popular, and it’s a valid one. You can purchase a large, stunning Ethiopian opal for a fraction of the price of a smaller Australian opal.
Like most gems, Opals can be found at a sweeping breadth of price points. On average, however, Ethiopian Opals cost significantly less than Australian Opals. It’s not hard to find a beautiful Ethiopian gem, much larger than an Australian Opal stone, for a fraction of its cost.
Due to the durability and care issues discussed earlier, the high-end jewelry market considers it a less "serious" gem.
Its price reflects unmatched stability, increasing rarity from historic mines, and its deep, saturated color.
Opal Evaluation
Individual opals can vary widely in appearance and quality. Opal evaluation should be done under controlled lighting on a dark background.
Opal hues can range across the spectrum. An opal might display a single color, two or three colors, or all the colors of the rainbow.
Opal displays background color in addition to play-of-color. All other quality factors being equal, many buyers favor the dark background color of black opal.
Fire opal is transparent to translucent with a bodycolor that is usually yellow, orange or red.
Boulder opals are opaque, giving them a mysterious look that’s ideal for designer jewelry pieces.
Crystal opal is transparent to semitransparent with a clear background. This type of opal can show excellent play-of-color.
Water opal might or might not display play-of-color.
Not every precious opal, however, sparkles with every color of the rainbow. These light-colored opal beads are milky in appearance and have numerous dead spots with no play-of-color.
Desirable play-of-color is further broken down by the colors themselves. Traditionally, red is considered the best prominent color, orange the next most desirable, followed by green.
In addition, an opal’s play-of-color can change along with the viewing angle or type of light.
In addition to the arrangement and shape of the play-of-color patches, buyers must consider extinction, or “dead spots,” when evaluating pattern. A dead spot is an area of the gem in which no play-of-color appears and only background color is visible.
With an opal, clarity is its degree of transparency and freedom from inclusions. An opal’s clarity can range all the way from completely transparent to opaque. Experts prize different levels of clarity for different opal types.
A cloudy or milky background color lowers the value of any opal.
Opals, like other gems, can have fractures, or pits and other surface blemishes. An opal might also contain fragments of its host rock, called matrix.
If an opal loses moisture, it can lead to crazing: a fine network of cracks that resembles a spider’s web.
