A Guide to Different Types of Opal and How to Identify Them

Gem Identification

A Guide to Different Types of Opal and How to Identify Them

Want to know whether an Opal is real or fake? Opals rank 5.5 to 6.5 on the Mohs Scale of mineral hardness due to their exact composition and formation conditions. Knowing the different types of opal can help you identify them and avoid falling for fake ones in the market.

The most common types are precious opal, common opal, fire opal, boulder opal, matrix opal, and crystal opal. You can identify them by looking at the color, pattern, and play of color of the stone. In this guide, we'll take you through their history, characteristics, and care requirements.

The History of Opal

The earliest known opal artifacts were in Kenya, dating back to about 4,000 BC. Opals also existed in ancient Egypt, where people used them as jewelry and other decorative objects.

In Roman times, opals were a symbol of hope and purity. Roman scholar Pliny the Elder wrote that opals were "the most valuable of all stones" and "possessed the power to change color." Ancient Greeks also believed that opals were a product of lightning and a gift from the gods.

In the Middle Ages, people believed opals had supernatural powers. As such, they were raw materials in talismans and amulets. Wearers of these items believed that they could protect them from evil.

Today, opals continue to be beautiful and valuable gemstones. They help make jewelry and are also popular collector's items. Australia is the world's leading producer of opals, accounting for about 95 percent of the world's opal production.

Other important opal-producing regions include the US, Mexico, Ethiopia, and Honduras. The stones form when water and silica mix in voids and cracks in rocks. The silica slowly hardens into a gel (which crystallizes into various colors), and the water evaporates.

Precious Opal

As the most valuable type of opal, precious opal is identifiable by its play of color. It is a popular collector's item and jewelry item.

So, how do I identify different opals? You can identify it by its body tone, opal pattern, brightness, and value.

Play of Color

The play of color in opal makes it so unique and beautiful. It stems from the refraction of light by tiny spheres of silica. The spheres are in a random order, and this causes the light to scatter in different directions, creating beautiful opal patterns and colors.

Body Tone

The body tone of an opal is the background color of the stone. It can be white, black, gray, or brown. The body tone can also be clear, but this is rare.


The pattern of an opal is the arrangement of the colors in the stone. But what are the different types of opal pattern?

It can be uniform, irregular, symmetrical, or asymmetrical. Common patterns in precious opals include Flash, Flood, Broadflash, Pinfire, and Harlequin.


The brightness of an opal is the intensity of the colors in the stone. It usually reflects the body tone, pattern, and quality of the opal. Though the brightness of a precious opal is subjective, the brighter an opal is, the more valuable it will be.


The most valuable opals have a strong play of color, a clear body tone, a uniform pattern, and high quality. But the play of color is the most important factor in determining the value of an opal. Opals with beautiful colors and patterns sell better than other opals.

The quality of an opal is also important for value. A high-quality opal will have a strong play of color and a clear body tone, making the colors appear brighter. Even more, rare or difficult-to-find opals are generally more valuable than opals that are more common.

Common Opal

Common opal is a type of opal that doesn't have the play of color that is characteristic of precious opal. It's often dull and opaque and doesn't show the same range of colors as precious opal. It is comprised of hydrated silica, a form of silicon dioxide-containing water molecules.

Water molecules trapped in the silica matrix give the opal its characteristic dull appearance. Common opal exists in various colors, including white, gray, black, brown, and red. The colors reflect the impurities that are present in the silica matrix.

For instance, iron oxide impurities can give the opal a reddish or orange color, while copper oxide impurities can give it a blue or green color. Sources of this stone include Australia, Mexico, Ethiopia, and the United States. It's a relatively common gemstone often used in jewelry.

There are several types of common opal, each with its unique characteristics. They include:

Boulder Opal

Boulder opal is a common opal found in a matrix of other minerals, such as ironstone or sandstone. It is often opaque and may have a milky or hazy appearance. You can find it in white, gray, black, brown, and red colors.

The play of color in boulder opal is not as strong as in precious opal. However, the opal can still be very attractive. Boulder opal helps make jewelry and is available in sizes ranging from small chips to large cabochons.

Fire Opal

Fire opal is a common opal characterized by its reddish or orange color. The color stems from the presence of iron oxide in the opal. Though the play of color in fire opal is not as strong as in precious opal, the opal can still be very appealing.

The body tone of fire opal can vary from clear to opaque. Like boulder opal, fire opal is a relatively inexpensive gemstone, making it a great option for those on a budget. It's also relatively easy to find, thus ideal if you want to buy an opal without searching for it extensively.

Milk Opal

Milk opal is identifiable by its milky or hazy appearance. It can help make jewelry items and is available in small chips and large cabochons. The body tone of milk opal can vary from clear to opaque.

If you are looking for an affordable and easy-to-find gemstone with a milky or hazy appearance, milk opal is a good option. However, it is important to note that the play of color in milk opal is not as strong as in precious opal. Its opaqueness means it doesn't allow light to pass through it.

Wood Opal

Wood opal is a type of common opal found in the matrix of petrified wood. The opal often has a mottled appearance and may contain remnants of the wood. It's a common raw material in jewelry.

The stone gradually forms when water and silica settle on cracks and voids in petrified wood. Afterward, the silica slowly hardens into a gel, and the water evaporates. The gel then crystallizes into a variety of colors that reflect the minerals that are present.

Other Types of Opal

There are other types of opals and value besides precious and common opal. They include matrix, doublet, triplet, synthetic, crystal and hydrophane opal.

Matrix Opal

Matrix opal is a type of opal found in a matrix of other minerals, such as ironstone or sandstone. It is usually opaque and may have a milky or hazy appearance. The name "matrix" refers to the material surrounding the opal.

Crystal Opal

Crystal opal has a transparent or translucent body tone and exhibits a play of color. It's popular for its beauty and rarity. Crystal opal often comes in blue, green, or pink, with a play of color that makes it so valuable.

Doublet Opal

A doublet opal comprises a thin layer of precious opal bonded to a backing of another material. The bonding material can be black onyx or matrix opal. Doublet opals help make jewelry items since they are more affordable than solid precious opals.

Triplet Opal

A triplet opal has a thin layer of precious opal joined onto a backing of another material, such as black onyx or matrix opal. It also has a top layer of clear quartz or resin. Triplet opals are even more affordable than doublet opals and are raw materials in costume jewelry.

Synthetic Opal

As a laboratory-made product, synthetic opal has the same materials as natural opal. Its production should take place in controlled conditions. Synthetic opal is more affordable than natural opal and is available in various colors.

The synthetic stone is available in blue, green, pink, yellow, and white. It can exhibit a play of color like other opals. However, synthetic opal is less valuable than natural opal despite its affordability.

Hydrophane Opal

Hydrophane opal changes color when it's wet. The opal is often opaque when dry but becomes translucent or even transparent when wet. Its name, "hydrophane," comes from the Greek words "hydro," meaning "water," and "phane," meaning "to appear."

The formation of hydrophane opal starts when water molecules enter the opal matrix. Once the opal dries, the water molecules remain tightly in place. However, when the opal is wet, the water molecules evaporate and become more transparent.

Hydrophane opal changes color when wet, depending on the amount of water molecules trapped in the opal matrix. Stones with a high concentration of water molecules will change color more dramatically than those with a low concentration. Hydrophane opal is relatively rare but exists naturally in Australia, Mexico, and Ethiopia.

In jewelry, the design of the opal can allow the wearer to see it change color when wet. Its colors are blue and green. Hydrophane opal also doesn't have the play of color characteristic of precious opal, a relatively rare and expensive gemstone.

How to Care for Different Types of Opal

Opals are beautiful and delicate gemstones that require special care. You should properly care for different opals to protect their beauty and maintain their value. Proper care also helps extend their lifespan.


Avoid using harsh chemicals, cleaners, or alcohol to clean opals. These soft gemstones can sustain damage from harsh chemicals or cleaners. You should also use a soft, damp cloth to clean your opal.

A mild soap and water can help you clean the stone. Rinse the opal thoroughly with clean water afterward. Also, avoid using ultrasonic or steam cleaners since they can damage the opal's structure.

Since doublet and triplet opals have two or three layers, be careful when cleaning them. Use a soft, damp piece of cloth to clean the top layer, but avoid getting any moisture underneath the backing.

Synthetic opals are often more durable than natural opals, but they can still react to harsh chemicals or cleaners. So you should use a mild soap and water solution to clean them.

Opalized wood is a type of opal that forms when opal replaces the organic material in wood. Since it's very fragile, be very careful when handling it. Don't clean opalized wood with any liquid, as this could damage the wood.


Store your opal in a soft, cloth-lined jewelry box. The box will help to protect the opal from scratches and other damage. Avoid storing your opal in direct sunlight or near heat sources since it can fade or become brittle if exposed to too much heat or light.

If you aren't wearing your opal, store it in a sealed container to prevent it from absorbing moisture. Store synthetic opals in a soft, cloth-lined jewelry box to protect them from scratches and other damage.

Don't store opals in plastic bags or containers since plastic can trap moisture and damage the stone. You should also avoid storing them with gemstones like diamonds, which can scratch them. Check the stone regularly for signs of damage, and take your opal to a jeweler for repairs if you notice any cracks or chips.

Buy Stunning Jewelry Pieces Today

Opals are popular for their beauty and rarity. The most common types of opal are identifiable based on the color, play of color, and pattern of the stone. You need to keep them in a cool, dry place away from extreme temperatures or chemicals to preserve their beauty, increase their value and extend their lifespan.

Philophrosyne creates stunning pieces that capture memories and love with the right designs, stones, and metals. We believe everyone deserves to have a bit of fabulousness in their lives. Send us your feedback and inquiries about our jewelry and we will get back to you within 1-2 business days.

1 comment

  • Frank Swaney

    My wife lost her last Opal ring. I’d like to get her a replacement

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