Opal is a hydrated amorphous form of silica with a water content that can range from 3% to 20%, but typically averages between 6% to 10%. Silica, composed of one silicon atom and two oxygen atoms, is the most common mineral found in the earth’s crust and is in a variety of other materials, including quartz, granite, and sand.
In the formation of opals, the silica builds up in layered planes, and this is where opal’s signature play of color comes from. When light diffracts with the unique internal structure of silica spheres, it produces the dazzling and valuable effect that opal is known for.
Opals form in areas where silica-rich water once existed, such as ancient lakes or hot springs. As water seeps into the ground, it dissolves silica from sandy soil and fills the cracks and crevices in rocks. Over millions of years, the silica hardens into the opals we have today.
On the Mohs hardness scale, opal ranks 5-6.5. This places it in the mid-range, making it susceptible to scratches from a variety of other gemstones, including diamond, ruby, sapphire, emerald, topaz, and more.
Opal is the October birthstone, along with tourmaline.
Bonus Reading: What is My Birthstone?
There are more than ten types of opal, some with surprisingly different appearances. We’ll discuss some of the most common types and a few of the less well-known ones.
White opal has a milky or creamy body color ranging from pure white to light grey. This type of opal is famous for its distinct play-of-color and can display a variety of colors in its flashes, including greens, blues, reds, and oranges. Each white opal is unique, and the more vivid and varied the play-of-color is, the more valuable the opal is. White opals are most commonly found in Australia, Ethiopia, and the United States.
Boulder opal is known for its distinct and bold appearance. It forms while attached to a host stone, typically an ironstone. Parts of the ironstone often become part of the boulder opal, creating a mesmerizing interplay between the dark, earthy colors of the rock and the opal’s vivid play-of-color. Flashes of color from the opal can be observed across the entire color spectrum. Boulder opal is typically found in Australia, and each mining area can provide boulder opals with distinct characteristics.
Black opals are among the most sought-after gemstones in the world due to their rarity and exquisite beauty. Black opals have a dark body color that ranges from black to dark blue to deep grey, creating a uniquely vivid contrast against the flashes of color they display. Black opals are most commonly found in Lightning Ridge, New South Wales, Australia, but are also found in other places, such as Ethiopia. High-quality black opal from Lightning Ridge can sell for more than $15,000 per carat.
Bonsu Reading: Learn more about black opals
Fire opal is a translucent to transparent type of opal known for its exceptionally vivid color, which ranges from yellow to deep orange to red. Fire opals are less likely to display the play-of-color found in other opals, and are typically valued for their fire-like color. While most of the opals we’ve mentioned so far are more likely to be cut into cabochon shapes, it’s not unusual to find faceted fire opals. Fire opals are primarily found in Mexico, but can also be found in Brazil, Honduras, Ethiopia, and Australia.
A welo opal, also known as a hydrophane opal, is a particularly unique opal known for its ability to absorb water. While most opals form in sedimentary rock, welo opals form in volcanic rock. While dry, a welo opal can have a uniquely distinctive and vibrant play of color. Once it has gotten wet and absorbed water, the flashes of color can lose their vividness, and the stone can become transparent. If the absorbed water was completely clean, the opal may return to normal when dry. If the water that was absorbed had anything in it (oils, perfume, lotion, etc.), it may permanently and adversely impact the opal’s appearance. A wet welo opal is more susceptible to damage, so it’s important to handle it gently until it dries. Welo opals are primarily found in Ethiopia, particularly the Welo and Delanta regions. Smaller deposits have also been found in Australia and Brazil.
Jelly opal, also known as water opal, has a gelatinous appearance. It can be found in a range of translucent levels and colors, from nearly clear to a soft, hazy blue or pink. The play-of-color in a jelly opal can be more subtle than other types of opal. Jelly opal is commonly found in Australia and Mexico, and sometimes in Nevada.
The term “opalite” can be used to refer to a natural form of common (does not display play of color) opal or to a man-made type of opal.
Natural opalite typically appears in green or purple. While it does not display play of color, it may exhibit chatoyancy, also known as the cat’s-eye effect.
Synthetic opalite is a man-made glass product composed of the mineral dolomite and metal compounds to imitate the soft glow of natural opal or moonstone. While it does not display true play of color, it can be visually stunning.
Most of the opalite found on the market is likely man-made.
The terms opal solid, opal doublet, and opal triplet don’t refer to a type of opal, but to the amount of authentic opal present in a specimen.
An opal solid means that only opal exists in the piece, with no layers of any other material present. An opal solid is more valuable than opal doublets or triplets.
Opal doublets have a thin, authentic top layer of opal, but have a backing made from another type of material, such as potch (common opal) or ironstone. This makes opal doublets more affordable than opal solids, but also more prone to damage.
Opal triplets have a very thin, authentic layer of opal with a backing like potch or ironstone, and a clear domed top like quartz or close. Opal triplets are the most affordable of these three options, but also the most prone to damage.
The answer to this question depends entirely on the type of opal that you have. Opals can either be hydrophane (which literally means “water-loving”) or non-hydrophane. Hydrophane opals absorb water like a sponge, while non-hydrophane opals do not absorb water, like a marble or piece of glass.
Although hydrophane opals are water-loving stones, they should not be submerged in water or have prolonged exposure to it. A few different things can happen if a hydrophane, like an Ethiopian Welo opal, gets wet and absorbs the water.
If the water is clean, the stone’s appearance will often change, becoming transparent or dull yellow-brown, and the play of color will vanish. If the water were truly clean, the opal’s appearance would likely eventually return to normal.
If the water is dirty with things like soaps, oils, or lotions, the opal will absorb these as well, which can permanently impact the opal’s appearance in a negative way.
For non-hydrophane opal solids, like many Australian opals, water is not absorbed and is not likely to damage the actual opal, though it may result in a loosened setting. However, non-hydrophane opals are often made into opal doublets and triplets, which can be affected by water, which loosens the adhesive holding the layers together.
Unless you know which type of opal you have, it’s recommended to proceed with caution when exposing it to water. Reach out to a professional, accredited jeweler in your area for more information about the specific opal(s) you have.
Among precious gemstones suitable for jewelry, opals are considered relatively fragile. They have a Mohs hardness rating of 5 to 6.5 and a toughness rating of very poor to fair. These ratings together mean that opals are easily scratched by a variety of other gemstones and can shatter upon impact. For these reasons, it’s important to be mindful of your cleaning method to keep them in their best condition.
It’s also best to take into account what kind of opal you have as detailed in the previous section, to make sure that you use the best method. Hydrophane opals, opal doublets, and opal triplets should not get wet and should be cleaned with a soft, lint-free, dry cloth.
Non-hydrophane opal solids can be cleaned using the following method:
Do not soak opals, especially opal doublets and triplets. Prolonged exposure to water can weaken the adhesive holding the layers together.
Do not use ultrasonic or steam cleaners, as the heat and vibrations can cause damage, such as cracks or fractures, to the opal.
Avoid exposing an opal to harsh cleaning chemicals, including bleach, ammonia, and alcohol-based cleaners. Avoid exposing an opal to body care products such as hairspray, perfume, or lotion.
Since opals are so soft, it’s best to store them separately from other gemstones, either in their own compartment or wrapped in a soft, lint-free cloth. Storing them in a dry environment can also damage them, so be sure to keep them in a slightly humid environment or create moisture by placing a damp cloth nearby.
Opal value is generally evaluated using a defined set of characteristics, which includes the type, body color, play of color directionality, play of color pattern, brightness, clarity, number of colors, size and cut, and origin:
There’s not a single answer for the question of how rare opal is because “opal” is not a single type of gemstone. For example, precious opal is much rarer than common opal, and black opal and boulder opal are much rarer than white opal.
Similarly, opals of exceptional quality using the properties listed in the previous section are very rare. Certain play of color patterns, like harlequin and pinfire, with a high brilliance can be very rare. Current fashion trends can also impact rarity due to market demands.
In general, precious opal is considered moderately to very rare. The more valuable an opal is based on characteristics like body tone, play of color pattern, play of color directionality, play of color intensity, clarity, brightness, and other factors, the more likely that type of opal is considered rare.
Real opals are considered opal solids that have formed naturally within the earth. Fake opals, on the other hand, can fall into a few different categories: assembled, synthetic, and imitation.
Assembled opals refer to opal doublets and triplets. While they technically contain slices of authentic opal, they are still less valuable than opal solids and should be labeled as such for transparency.
To check if an opal is a doublet or a triplet, use a 10x or higher loupe and look for a side seam where glue connects the authentic opal to the dark backing. In triplets, there will be an additional seam line separating the authentic opal from the clear top, which is usually quartz or glass.
For an authentic opal with a dark body tone, the dark body tone will extend throughout the entire stone, while a doublet or triplet will only have uniform darkness on the back.
Synthetic opals refer to lab-created or man-made opals. Different from imitation opals, synthetic opals are silica-based like natural opals, but their microstructure differs, resulting in a more uniform and orderly play of color than natural opals. They also differ from natural opals in their origin and value.
Differences in microstructure are among the easiest ways to identify synthetic opals. Because of their uniform silica structure, the play of color pattern and the brightness may appear too consistent and orderly. If viewed from the side, synthetic opals can sometimes show column-like vertical stacks, which are rarely visible in natural opals.
Another clue is to use a UV light, but this is far from a guarantee. Many synthetic opals injected with polymer will shine a uniform and bright green, while natural opals' UV response varies by region. A natural opal may lack a vivid glow, but it may also glow green or blue under a UV light. So while it doesn’t provide a definitive answer, it can be helpful information to have.
Popular types of imitation opal include resin and glass. The glass-based Opalite is a good example. One way to check if a stone is an imitation opal is to use a 10x or higher loupe to look for gas bubbles and curved flow lines. Natural and synthetic opals will not have either of these.
For Opalite, the main difference is in the lack of play of color. Opalite can be visually striking, with a beautiful blue glow, and sometimes exhibits chatoyancy (cat’s-eye effect). However, it will not display the visible shift in the play of color that occurs when a real opal is moved back and forth.
The majority of opals come from Lightning Ridge, Australia. It’s estimated that Australia produces 95% of the world’s opal supply, including the rare and highly coveted black opal. Ethiopia is the second-largest producer of opals. Other significant sources include Brazil and Mexico.
Disclaimer: The symbolic and metaphysical meanings associated with opals are based on historical traditions, folklore, and personal beliefs. This information is provided for educational and entertainment purposes only and should not be considered medical, psychological, or professional advice.
We’ve compiled an introduction to opal symbolism across cultures and time:
Each type of opal also has specific meanings that correspond with it:
It is the opinion of Nelson Coleman Jewelers that opals are not cursed and are, in fact, stunning and mesmerizing gemstones. However, we’ll share the reason why opals are sometimes rumored to be cursed, and you can decide for yourself.
Opals were highly revered in ancient times, especially by the Romans, and were considered by many to be the ultimate gemstone because they could display a wide range of colors. In the early 19th century, Australian opal had gained significant popularity and was often worn by nobility.
In 1829, the Scottish author, poet, and historian Sir Walter Scott wrote a Gothic novel titled Anne of Geierstein, sometimes called The Maiden of the Mist. It was the 24th book of his Waverley Novels, which remained one of the most popular and widely read series in Europe for nearly a century. The novel was split into three volumes, and it’s in the first volume, chapter 11, titled “Donnerhugel’s Narrative,” that we find the likely origins of the myth that the opal is a cursed gemstone.
In the novel, the titular character’s grandmother, Lady Hermione, regularly wears an opal talisman in her hair. She is described in legend as almost supernatural. The opal is described as magically responsive to her and as changing color to reflect her moods and temperament. It glows when she is excited, turns red when she is angry, and she is also afraid to get it near water. Because of this, she gets a reputation with the townspeople for being eccentric and perhaps practicing witchcraft. One of the most vehement accusers of Lady Hermione is the Baroness of Steinfeldt, an elderly woman known for her pride, gossip, and stirring up rumors.
On the day of her child’s christening, Lady Hermione and her husband, The Baron, go to the church where it will happen. As her husband enters the church, he dips his hands in the holy water to bless himself and also to touch his wife’s forehead. Upon touching her, a drop of water falls upon the opal, and it glows brightly before becoming dull and lifeless. At that moment, Lady Hermione collapses. She is taken back to her home and put in bed to rest. The next day, when her door is opened, nothing but a pile of ashes remains where she once lay.
However, if you were to continue reading the second volume, until at least chapter 10 titled “The Interview,” you would learn from Anne what she considered the truth about her grandmother, Lady Hermione’s death. Anne believed that her grandmother was, in fact, a bit eccentric and that she enjoyed fueling the townspeople's rumors about her, but that many of the rumors were more fanciful than reality.
Lady Hermione did, in fact, have an opal whose energy, allegedly, was somehow entwined with her own, and she was afraid to get the opal wet. But Anne claims that’s about as accurate as the myth was and goes on to share what she and her family believe really happened.
They believe that the timing of the holy water placed on Lady Hermione and her collapse was completely coincidental. The real cause of her death, Anne believes, was poisoning by Lady Steinfeldt, presumably earlier in the day, before she arrived at the church. Anne’s interpretation of the opal glowing brightly was not because of a reaction to the water, but because it was a signal that Lady Hermione’s life was in danger as the effects of the poison began to set in. While the narrative doesn’t fully resolve all the details, it exonerates the opal talisman of causing her death.
So, how did opal get a bad reputation from this story if it was eventually exonerated? Historians don’t completely agree on it, but some speculate that perhaps enough people read the first volume without reading the second one to clarify what actually happened. Or perhaps not enough people read the second volume carefully enough to connect it to the events in the first volume.
Perhaps the initially established connection between the opal and death was too shocking and strong to be completely dissolved by Anne’s attempt at a logical explanation eleven chapters later. Whatever the reason, some sources report that opal sales declined sharply shortly after the publication, although we’ve not been able to find any supporting evidence. The thing historians generally agree about is that Scott’s novel was a major literary influence behind the myth that opals are connected with death and are unlucky.
Opals have dazzled and mesmerized civilizations for centuries. Their distinct play of color creates an almost magical appearance and adds a touch of whimsy to any jewelry design. With a variety of types, including synthetic opals, they are available in many price points and styles. Browse Nelson Coleman Jeweler’s full collection of opal jewelry today or design a bespoke piece with custom jewelry design.
