Skip to Content

Real vs. Fake Opal: Focus on These 6 Differences

As an Amazon Associate, I earn from qualifying purchases with no additional costs for you.

Opal is highly praised for its kaleidoscopic play of color. Sometimes, opal’s mesmerizing optical effect is compared to fireworks, jellyfish, galaxies, or lightning. Many different fakes have been created to make the opal affordable to a wider range of people.

The most common fake opal is assembled stone. Doublets or triplets can be distinguished by the side view, in case they are not enclosed into metal. Plastic, glass, and synthetic fake opals are also widespread. Unlike the natural opal, they can have a columnar structure or lizard skin surface texture.

In today’s gem market, buyers need to be well-informed and cautious, as the prevalence of fake opals and their high prices can make purchasing a genuine stone a daunting task. To help you navigate this complex landscape, we’ve prepared a comprehensive guide that will empower you with the knowledge needed to make a confident and informed decision when shopping for opals.

How to Tell and Identify if Opal is Real or Fake?
How can you tell and identify if Opal is real or fake?

If you are interested in checking out the best rockhounding tools I recommend and use, you can find them here (Amazon link).

How to Tell if Opal is Real

Opal, unlike other gemstones, is not a mineral. Opal is a mineraloid. It means that opal doesn’t have a crystal structure. It is an amorphous and hydrated version of silica. Opal is made up of microscopic spheres arranged in a grid-like pattern.

Water content in opals can reach up to 20 percent. That is why the recommendation to store opal away from sunlight exists. Opal occurs in rock fissures. Some rocks where opal can form include basalt, limonite, and rhyolites.

Real opal possesses a magnificent play-of-color or iridescence spread evenly but not irregularly. It occurs in various colors, from white through the rainbow spectrum to black. It has no brown spots of soot or columnar structure.

Play-of-color or opalescence occurs in precious opal because of light diffraction. When the lightwaves travel between the silica spheres, they diffract or bend.

As they bend, they break up into the colors of the rainbow or spectral colors. And we can observe the result of this process as play-of-color or iridescence.

The color depends on the sizes of the spheres. Spheres approximately 0.1 microns (one ten-millionth of a meter) in diameter produce violet. Spheres about 0.2 microns in size produce red. Sizes in between producing the remaining rainbow colors.

Australia is the biggest supplier of opals in the world (from 80 to 95 percent), and opal is the national gemstone of the continent.

How to Identify Real Opal

Opal is a beautiful and unique gemstone that is highly sought after by collectors and jewelry enthusiasts. However, with the rise of imitation opals on the market, it can be challenging to determine whether an opal is genuine or fake. In this article, we’ll discuss some key factors to consider when identifying real opal.

1. Solid Structure

One of the most important characteristics of real opal is its solid structure. Unlike imitation opals, which may be composed of different layers or materials, genuine opal is a solid stone throughout. When viewed from the side, real opal should appear uniform and not exhibit any distinct layers or column-like structures.

2. Consistent Play-of-Color

Another hallmark of real opal is its play of color – the mesmerizing display of flashing colors that shift and change as the stone moves. In genuine opal, this play-of-color should be evenly distributed throughout the entire body of the stone and appear consistent when viewed from different angles, including the front and side.

3. Absence of Columnar Structure

When examining an opal from the side, pay close attention to its internal structure. Real opal should not exhibit any columnar or layered appearance. It is likely an imitation opal if you notice distinct columns or a “stacked” look within the stone.

4. No Lizard Skin or Snakeskin Effect

Some imitation opals may display a regular, ordered pattern of color flashes on their surface, known as a “lizard skin” or “snakeskin” effect. This is a telltale sign of a fake opal, as genuine opals do not exhibit such uniform patterns. The play-of-color in real opal is more organic and random in its distribution.

5. Absence of Soot Points

Lastly, when inspecting an opal, check for the presence of small dark spots or “soot points” within the stone. These soot points can indicate that the opal has been subjected to treatments such as smoking or sugar treatment, which are sometimes used to enhance the appearance of lower-quality opals. A genuine, untreated opal should not contain any soot points.

Composition and Homogeneity

It’s important to note that real opal is composed primarily of silica, not glass, plastic, or resin. Genuine opal is also very homogeneous when viewed from different angles, maintaining a consistent appearance throughout the stone.

By keeping these characteristics in mind and carefully examining any opal you are considering purchasing, you can help ensure that you invest in a genuine, high-quality gemstone. If you are ever unsure about the authenticity of an opal, it is always best to consult with a qualified gemologist or reputable jeweler for a professional assessment.

Identifying Real Fire Opal

The real fire opals are of yellow, orange, and red colors and display a distinct play-of-color. They are homogeneous and have no ordered column structure or lizard skin effect when viewed from different directions.

The real fire opal comes from two countries, Mexico and Ethiopia. Sometimes, they have other trade names, such as Cantera opal, Shewa opals, Mezezo opals, and Welo opal (wollo or wello).

Identifying Real Pink Opal

The most important characteristic of real pink opal is its milky pink uniform color. It’s OK to be translucent or semi-opaque for a real pink opal. Most real pink opals come from Peru. So do not hesitate to ask about the origin of the stone.

The real pink opals do not occur in the form of big boulders. They are about half a centimeter across and range in color from nearly white through carnation pink to lilac.

Real pink opals are mixed slightly with chalcedony during the formation process, which is why they are somewhat harder than other types of opals.

Identifying Real White Opal

It’s almost impossible to identify real white opal with the naked eye. The best professional advice we can share with you is to ask the dealer about the origin. If the origin has stayed as Coober Pedy or Mintabie (Australia), you can be safe.

Real white opal is translucent to opaque-white or other light color backgrounds with distinct play-of-color.

TIP: Correctly cutting and polishing opals brings beauty and exceptional color flash. Find out the step-by-step guide on how to cut and polish opals in the article below:
How to Cut & Polish Opals: Follow These 9 Simple Steps

Identifying Real Black Opal

The Black opal is a term used for opal with a dark body color, usually black or dark gray. The term is also applicable to opal that has a dark blue or dark green body color.

Real black opal is the rarest and the most expensive type of opal. That is why most opals are smoked to enhance their body color and raise the price.

Real black opals should not have any soot patches on the surface, which tell about smoke or sugar treatment. It’s always a good idea to check the origin locality. For real black opals, they are Lightning Ridge, New South Wales, Mintabie, or Coober Pedy, South Australia.

Identifying Real Blue Opal

Real Peruvian blue opal (also called blue opal) is a semi-opaque to opaque blue-green or turquoise-color gem.  It does not display a play-of-color. The color is milky and homogeneous.

Blue opal also comes from Oregon and Idaho in the Owyhee region and Nevada around the Virgin Valley.

Identifying Real Mexican Fire Opal

Mexican Fire Opal has a bright red, orange, or yellow background color that is mostly transparent or translucent. Most of them do not have precious iridescence, but these warm colors of natural red Mexican opals are highly praised.

Real Mexican fire opals have their own very specific type called Cantera Opal. Orange color opal enclosed into a rhyolites host rock. Cutters simply cut a cabochon from rhyolite with a fire opal window in the dome.

Identifying Real Ethiopian Opal

Real opals from different locations have no specific characteristics as, for example, some exotic inclusions in sapphires or emerald can disclose their provenance.

A good tool to distinguish a real Ethiopian opal among Mexicans or Australians is to check the trade names: Shewa opals, Mezezo opals, welo opals, wollo, and wello opals. Also, Ethiopian opals are usually very porous. So, the specific gravity of this type of opal is slightly lower.

Much of the Ethiopian opal produced from the Wollo province has an orange, yellow, or reddish body color along with play-of-color.

Identifying Real Australian Opal

Most of the opals available on the market came from Australia.

The best way to identify the real Australian opal is to ask the direct locality where the opal was mined. They are Coober Pedi, Mintabie Opal Field, Andamooka, Lightning Ridge, Jundah, and Quilpie. Some real Australian opals are formed in the iron-rich rock called ironstone and have wooden structures.

TIP: Opals are among the most beautiful gemstones you can find in nature. Check out the best locations for finding opals in the United States in the article below:
4 Best Locations for Finding Opals Near Me (United States)

How to Tell if Opal is Fake

Before the identification of fake opal, let’s differentiate the most common types of opal fakes.

Fake opal made of glass can be identified by tiny films inside, round bubbles, or swirls. Fake opals made of plastics and resins will have very even opalescence, which is regularly ordered. Assembled fake opals are made of two or three layers visible from the side view.

Classic Fake Opals

The common types of fake opals are made from:

  • Glass

A manmade glass is an age-old gem imitation widely used today. Modern technologies allow the production of a glass of any color.

That is why it is the most popular imitation of many gems. Opal is no exception. Glass material known as “Slocum stone” can mimic the appearance of opal.

Slocum stone is a silicate glass with thin translucent flakes of iridescent film, which produce an opal-like play-of-color.

Opalescent glass is the other widespread opal simulant. It is a man-made glass with a sheen-like luster which is perceived as an opal effect by many people.

  • Resins and plastic

The second fake opal group is represented by resins and plastic.

Sometimes, man-made plastic with an opalescence effect is marketed as “opalite.” The high resin content of these opals changes the material’s physical properties.

Opalite usually has lower specific gravity than natural opal and a lower refractive index. Also, plastic and resins can be identified with a hot metal needle.  Needle touch evokes a burnt plastic odor.

Fake Opal made from Assembled Stones

This group is not fake in its classical meaning. There is natural opal, but in a very small amount.

Assembled stones are pieces of natural and/or synthetic material fused or glued together to enhance the quality of the stone, protect it, or increase the weight of the material and, as a result, increase its value.

We will put assembled or composite stones into the fakes list because such types of opal are usually sold and embedded into jewelry pieces, and sellers prefer not to disclose the truth.

Assembled stones can be divided into two groups. They are doublet and triplet.

A doublet consists of two joined segments. Speaking about fake opal, they are

  1. Thin quality dull natural opal and 
  2. Black opaque quartz, chalcedony, black onyx, obsidian, or plastic glued together.

A triplet has three segments. The first two are the same as in the previous example. The third one, cabochon or dome, which overlies the opal, is made of transparent quartz, glass, plastic, or synthetic corundum. The result is a thin opal plate enclosed between two non-opal material segments.

Fake Opals made by treatment

Natural opal porosity makes them good candidates for dye, smoke, and sugar/acid treatments.

The sugar/acid treatment is done by soaking the opal for a few days in a warm sugar water solution, then submerging the opal in sulfuric acid.

The acid oxidizes the sugar in the pore spaces of the opal, producing dark-colored carbon particles and stains. This imparts or darkens a gray, black, or brown body color in the opal.

Synthetic Fake Opals

Another type of fake opal can be described as lab-created, lab-grown, or synthetic opal.

But here, it is not fully appropriate to call it fake because the composition, physical properties, and, eventually, appearance are the same as that of a natural one. So, let us just mention lab-created opals here but thoroughly describe them in a separate paragraph.

TIP: Rockhounding is a great hobby, but did you know you could actually make a good income from it? A lot of people are making money by selling rocks. Find out more in the article below:
Ultimate Guide: Making Money by Selling Rocks & Minerals

How to Identify Fake Opal?

Fake opal can be identified by color flashes organized in a repeated pattern. Fake opals made of glass can be easily identified by swirls or bubbles inside or conchoidal fracture. Fake opals glued from different materials can be identified when viewed from the side. Synthetic opals have lizard skin texture.

  1. Fake opal is too shiny. It displays various color flashes organized in a repeated pattern.
  2. Fake opals made of glass will have swirls and round bubbles inside. Also, they will have a conchoidal fracture.
  3. Fake opals are composed of different plates glued together.
  4. Fake opals have a columnar structure viewed from the side.
  5. Fake opals made of plastic produce a burnt plastic odor when touched by the hot metal needle.

How to Tell if Opal is Lab-Created

Lab-created (lab-grown) or synthetic opal will have systematically ordered color flashes or lizard skin effects. Synthetic opal has a columnar structure that can be viewed from the side. Synthetic opal is more porous than natural; it has lower density and does not fluoresce under UV light.

In the 1970s, the Gilson Company developed a three-step process, which generally repeats the natural environment, to make convincing synthetic opal.

  • The first is silica sphere precipitation.
  • The second is they settle in acidic water for more than a year.
  • The third is a consolidation of spheres under a hydrostatic press.

This synthetic opal can be very difficult to identify. If the opal has been created in a laboratory, the pattern will display bright colors in large patches of color.

  • The pattern is often ‘too perfect’ and systematically ordered and can also often display a snakeskin or lizard skin pattern.
  • Synthetic opal also has a columnar structure. Straight columns of color running vertically from the side can be observed. This is the sign of a fake opal.
  • One characteristic that distinguishes synthetic opals is that they are much more porous than natural ones.
  • Synthetic opals also have lower density compared with real opals, and for this reason, synthetics tend to be lighter.
  •  Another indication that opal is synthetic is that it does not fluoresce when lit with UV light.

TIP: Opal is a one-of-a-kind, highly valuable gemstone. Find out the key factors that determine opal’s value in the article below:
8 Factors Why Opal is Valuable (Prices for Different Types)

Real vs. Fake Opal: The Main Differences

The history of fake opals is extremely long. It’s getting harder to distinguish fake opal from a natural one. Here you are welcome to check a table with the main differences between natural and fake opal.

However, we kindly recommend you seek the help of a professional gemologist in case of an expensive purchase.

PropertyReal OpalFake Opal
Hardness5,5 — 6,5 the Mohs scalePlastic and resin-made type of fake opal will have lower hardness: 5 -5,5
Play-of-colorFlashes will be organized in random orderSynthetic fake opal will have a uniform repeating pattern and ordered flashes
SurfaceReal opal will have a smooth surface with random flashesLab-grown will have lizard skin or snakeskin effect. 
Side viewIt Will be similar to the front viewLab-grown: Will have a columnar structure. Assembled stones: Doublet is composed of two different materials triple – composed of three different layers.
Presence of black or brown points (soot)No inclusions should be found in untreated natural opal.Soot inclusions are a sign of treated natural opal. (Some people do not think it is fake, but this kind of treatment should be disclosed to every person).
UV lightFluorescenceSynthetic opals do not fluoresce under UV light.
Real vs. Fake Opal: The Main Differences

BTW: Do you want to know more about rock and mineral identification? The books listed below are the best ones you can find on the internet (Amazon links):


Natural opals are gemstones of the best appearance and the most intriguing optical effect. Because of the high demand for opals, fakes are extremely widespread.

People usually run into plastic substituents and assembled stones, which are easy to identify with minimum effort. It is far more complicated in cases with lab-grown fake opals, and it’s always better to ask for a professional gemologist‘s assistance.

TIP: Not only opals but also other rare rocks are often sold fake. Find out more about the differences between real and fake selenite and agate in the articles below:
Real vs. Fake Selenite: Focus on These 5 Differences
Real vs. Fake Agate: You Should Know These 7 Differences