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by Freya Branwyn June 20, 2023

Are Moonstone and Opal The Same

Gemstones have fascinated people for centuries, with their extraordinary beauty and mystical properties. They have been used for various purposes throughout history, from adornment to healing. 

Two such stones that have piqued the interest of many are moonstone and opal. Both are unique in their appearance and properties, but a question that often arises is whether they are the same?

Brief Overview of Moonstone and Opal

Moonstone is a gemstone that belongs to the feldspar group of minerals. It is known for its iridescent play of color or adularescence, which creates an ethereal glow that seems to move across the stone's surface as it catches the light. 

The stone's name comes from its similarity in appearance to the moon's soft white glow. Opal, on the other hand, is a hydrated amorphous form of silica. 

It is prized for its brilliant flashes of color or play-of-color caused by interference and diffraction of light within its internal structure. This effect gives opals their distinctive fiery appearance. 


Question: Is there a difference between a moonstone and an opal?

While both exhibit colorful flashes at certain angles, there are significant differences between them in terms of composition and optical properties. 

In this article, we will delve deeper into these differences as we explore what makes each stone unique. We will also examine some similarities between them, along with some gemological tests you can use to tell them apart if you encounter them in your collection or shopping experiences. 



The mysterious gem of the moon

Moonstone is a beautiful, ethereal stone that has captured the hearts of many throughout history. It is a type of feldspar mineral that exhibits a unique phenomenon known as adularescence. 

This natural effect creates an iridescent glow or sheen on its surface, resembling the gentle glow of the moonlight. Its name comes from this similarity to the moon.


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Historically, it was believed to carry within itself the energy of the moon and was therefore considered sacred by many cultures throughout time. In ancient Rome, it was believed that Moonstone was formed by solidifying beams of moonlight. 

In India, it was said to bring good fortune and protect against evil spirits. The stone also holds significance in Native American cultures where it is thought to represent new beginnings. 

Physically, Moonstone varies in color from pale white to peachy orange or greyish blue. It has a hardness level of 6-6.5 on Mohs scale making it relatively durable but still requires gentle handling as it can be prone to scratches and chipping if not taken care properly. 

It is typically found in countries such as Sri Lanka, India, Madagascar and Myanmar among others. Moonstone is not just a beautiful gem but also one that holds deep cultural significance for many people around the world due to its unique properties and history. 



Definition and Characteristics

Opals are a type of mineraloid composed primarily of hydrated silica. Unlike other gemstones that have a crystalline structure, opals have an amorphous structure. 

This means that they don't have a defined shape or symmetry, leading to their distinctive appearance. Opals can come in many different colors and patterns, but they are best known for their iridescence, or play of color. 

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This optical effect occurs because the light enters the opal and is then diffracted by tiny spheres of silica within the stone. One unique characteristic of opals is that they can contain up to 30% water content. 

This makes them susceptible to cracking or crazing if they are exposed to heat or dehydration. To prevent this from happening, opals should be stored in environments with moderate humidity and kept away from sources of heat. 


History and Cultural Significance

Opals have been prized for their beauty since ancient times. The ancient Greeks believed that opals gave their owners the power of prophecy and foresight, while the Romans believed they symbolized hope and purity. In medieval Europe, opals were thought to possess healing properties that could cure diseases and protect against evil spirits. 

In modern times, Australia has become one of the largest producers of high-quality opals in the world. The Australian government even named "opal" as its national gemstone in 1993. 


Physical Properties

Opals typically have a hardness rating between 5.5-6 on the Mohs scale, which means they are relatively soft compared to other gemstones like diamonds or sapphires. They also have a low specific gravity (density) compared to most other minerals. 

The color range for opals can vary greatly based on where they were formed geologically; however, they are typically found in shades of white, yellow, orange, green, blue, purple and black. Opals can be found all around the world but are primarily mined in Australia. 


Differences between Moonstone and Opal

Color range: Not All That Glitters is Gold

One of the primary differences between moonstone and opal is their color range. While both gems have a unique range of colors, they differ significantly. Moonstone often comes in pale blue, green, and pink hues with a distinctive sheen. 

On the other hand, opals are known for their iridescence and can take on almost any color in the spectrum. From red to green to blue to yellow, opals have an unmistakable glimmer that makes them stand out in any gem collection. 

Additionally, some types of opals are famous for their patterns such as harlequin or flame effect. While moonstones are known for its adularescence effect which looks like a floating shine on the surface of the stone. 

Optical Properties: How They Play with Light

Another significant difference between moonstone and opal is their optical properties. Moonstones show off an unforgettable phenomenon called adularescence caused by light diffraction through microscopic layers of feldspar within the stone. This gives the stone a floating, dreamy glow that sets it apart from other gemstones. 

Opals also exhibit optical properties but in a different way: play-of-color where silica spheres contained within refract light creating rainbow-like flashes within them. It's this characteristic that's made opals coveted by collectors around the world.


Chemical Composition: What Lies Beneath

Moonstones are primarily composed of orthoclase feldspar minerals with scattered deposits of albite which give it its milky appearance. On the other hand, opals owe their particular properties to hydrated silicon dioxide or silica spheres that form over hundreds or thousands of years. 

While both mineral compositions may seem similar at first glance - they are not interchangeable. Moonstone and opal contain unique properties that make them distinct from one another, and it's the differences between the two that make them so sought after in the world of gemstones. 


Similarities Between Moonstone and Opal Formation process

Moonstone and opal may have distinct differences in appearance, but they share a similar formation process. Both gemstones are formed through a type of rock called igneous rock. This rock is created by volcanic activity or intense heat and pressure beneath the earth's surface. 

Over time, dissolved minerals such as silica or aluminum oxide can seep into the gaps within the rocks. As these minerals cool and harden, they create patterns and forms that ultimately become opals or moonstones. 

Another similarity in their formation process is that both gems are classified as mineraloids rather than minerals. This means that they lack the crystal structure found in most minerals but still possess some physical characteristics of minerals. 


Healing Properties

In addition to sharing a similar formation process, moonstone and opal also share some healing properties. Both gems are believed to have calming effects on the emotions, promoting emotional stability and peace within oneself. 

They are often used for meditation practices due to their calming nature. Moonstone is also thought to have a strong connection with femininity, fertility, and motherhood. 

It is said to aid in regulating menstrual cycles as well as balancing hormones during menopause. Opal, on the other hand, has been associated with enhancing creativity and inspiration while promoting confidence in one's abilities. 

It is believed to help one express themselves more freely. Overall, while moonstone and opal may differ greatly in appearance and chemical composition, they still share some similarities in their formation process as well as their potential healing properties. 


How to Distinguish Between Moonstone and Opal

When it comes to identifying moonstone and opal, there are some key visual differences to look for. Moonstone tends to have a more translucent appearance with a milky or bluish sheen. 

The color can range from white to gray, with hints of peach or blue in some varieties. Opals, on the other hand, tend to be more opaque with a fiery play of colors that changes depending on the angle of light. 

The color range of opals is much wider than moonstones and can include reds, greens, yellows, blues, purples and more. Another visual cue is the pattern within the stone. 

Moonstones often have a characteristic “adularescence” effect where there appears to be a glowing band just below the surface as you move the stone around in your hand. Opals have unique patterns that are formed by their internal structures which create flashes of color known as “fire”. These patterns can vary widely between different types of opals. 


Gemological Tests

While visual cues can be helpful in identifying moonstone and opal, gemological tests are often needed for a definitive answer. One simple test that can be done at home is called the scratch test: use one stone to scratch against another and see which one leaves a mark (if any). 

Moonstones are typically softer than opals so they will scratch more easily. However, this test alone is not always reliable as some types of moonstone are harder than others. 

Another gemological test involves using a polarizing filter to examine how light passes through the stone. This technique helps identify both internal structure and composition which can help differentiate between moonstones and opals. 

Ultimately, if you want an accurate identification of your gemstones it's best to take them to a professional gemologist who has the equipment and expertise to perform a range of tests. With their training and experience, they can help you distinguish between moonstone and opal, as well as provide valuable information about the quality and value of your stones. 



Recap of key points: In this article, we have explored the world of moonstone and opal. We have learned about their unique characteristics, cultural significance, physical properties, and differences. Moonstone is a type of feldspar with a white or blue glow caused by adularescence. 

Opal is formed from silica and has a wide range of colors and patterns that change with angle and lighting. Though they share some similarities in healing properties and formation process, they are fundamentally different. 

Final answer to the question: Are they the same?

No, moonstone is not the same as opal. While they may look similar at times due to color variations or patterns that mimic each other, their chemical composition, optical properties, and formation processes set them apart. Moonstone has a more subtle glow while opal has a vibrant play-of-color phenomenon that makes it highly sought after in jewelry making. 

They both have unique cultural significance throughout history but are distinct gemstones. Whether you prefer the soft beauty of moonstone or the radiant brilliance of opal in your jewelry collection will come down to personal preference. 

Both stones have their own unique qualities that make them precious in their own right. The world of gemstones never ceases to amaze us with its diversity!


Find your next bohemian treasure at www.FreyaBranwyn.com



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Freya Branwyn
Freya Branwyn

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