Moonstone vs. Opal: Differences in Appearance & Meaning

Everything you need to know to choose your perfect gemstone

Co-authored by Alisa Thorp

Last Updated: March 4, 2023 References

Are moonstones and opals the same?

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Location

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Color and Luster

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Symbolism and Meaning

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Value

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How to Choose the Right Gem

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Expert Interview

There are thousands of beautiful gemstones worldwide, but few are as alluring as moonstones and opals. Both gems have an ethereal quality, and it’s common for moonstones to be mistaken for opals. Although both can have a milky color and blue shimmer, opals and moonstones have major differences in appearance and meaning. To help you choose your perfect gem, here’s a guide on everything you need to know about moonstones and opals.

Things You Should Know

Moonstones and opals are two different gemstones. Opals come in endless colors, while moonstones are usually clear or white.
Opals are more valuable than moonstones because of their rarity and uniqueness–no two opals are alike.
Moonstones have a unique property known as adularescence, which gives the stone an ethereal sheen.

Section 1 of 6:

Are moonstones and opals the same?

1
Moonstones and opals are two different gemstones. Although some moonstones look similar to opals, opals are more valuable and unique. No two opals are alike, so they come in a broad range of colors and patterns. Moonstones are typically colorless or white, but they have an optical phenomenon known as adularescence (Schiller’s Effect), which gives the stone its unique shimmer.^{[1]
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- People often describe a moonstone as a drop of water glowing underneath the moonlight.
- Opal is the official birthstone for October, while moonstone is one of three birthstones for June (pearl and alexandrite are the other two).^{[2]
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  Trustworthy Source
  Gemological Institute of America
  Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
  Go to source}
2
Moonstones and opals have different chemical compositions. Moonstone belongs to the feldspar group, one of the largest mineral groups on Earth, and it’s composed of albite, orthoclase, and feldspar minerals.^{[3]
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Research source} Opal, on the other hand, belongs to the Silicates Quartz group and is formed by water and silica.^{[4]
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- The chemical formula of moonstone is KAl₃O₈, while the chemical formula of opal is SiO₂.nH₂O.^{[5]
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Section 2 of 6:

Location

Moonstones are found globally, while most opals are mined in Australia. India and Sri Lanka are home to the highest quality moonstones, but other moonstone varieties have been discovered in Armenia, Australia, Brazil, Madagascar, Mexico, and the United States.^{[6]
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Research source} Opals are also mined globally, but Australia is home to 95% of the world’s finest opals.^{[7]
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- Opal is the official national gemstone of Australia.

Section 3 of 6:

Color and Luster

1
Moonstones are usually clear or white, while opals are colorful. There are only 3 varieties of moonstone: transparent, translucent, and opaque.^{[8]
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Research source} In contrast, opals come in a variety of colors and finishes: white, black, brown, purple, orange, red, and yellow (just to name a few).^{[9]
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- Opal coloring is determined by the arrangement of silica spheres in the gemstone.^{[10]
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- Inclusions, or materials trapped during gem formation, give moonstones their milky, white finish.^{[11]
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2
Moonstones have a distinct shimmering effect, unlike opals. Moonstones have a unique property known as adularescence (Schiller’s Effect), which gives a subtle, reflective sheen to the gem. Light enters the stone, interacts with its layers, and scatters, creating a glowing optical effect.^{[12]
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- Opals have a phenomenon known as play of color (opalescence): light reflects off the silica spheres inside the gem, giving opals fiery flashes of color.^{[13]
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Opals are more susceptible to scratches than moonstones. Opals have a hardness of 5.5-6.5 on the Mohs scale of mineral hardness, while moonstones rank a 6-6.5.^{[14]
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Research source} Opal is generally stable, but intense heat or light can create fracture lines.^{[15]
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Trustworthy Source
Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
Go to source}
- Moonstone can withstand harsh light, but it’s highly prone to breakage: most manufacturers set moonstones into pendants or earrings because they’re less prone to damage (vs rings).^{[16]
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  Trustworthy Source
  Gemological Institute of America
  Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
  Go to source}

Section 4 of 6:

Symbolism and Meaning

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Moonstones symbolize fertility, while opals represent protection. For women, moonstone activates connection to the divine feminine, and it’s considered a powerful healer for the female cycle.^{[17]
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Research source} Many ancient cultures believed opals protected them from disease, helping the wearer become “invisible” in dangerous situations.^{[18]
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Trustworthy Source
Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
Go to source}
- Moonstones were associated with lunar deities in the Greek and Roman Empires. During full moons, the ancient Romans believed they could see into the future if they held a moonstone in their mouth.^{[19]
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Moonstones are calming, while opals enhance intuition and creativity. Associated with the moon, moonstone promotes stability and emotional balance. It cultivates empathy toward yourself and others, allowing you to process situations from a different perspective. Opal improves psychic abilities and creativity. Having an opal nearby opens the mind to its inner creativity, encouraging new ideas and insight.^{[20]
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- Moonstone is a wonderful option for individuals who are more sensitive or stressed than others. It’s known to be grounding during emotional times, and it can help you maintain positivity in the presence of negative people.^{[21]
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Section 5 of 6:

Value

Opals are typically higher value than moonstones. Moonstones range from $5-$50 per carat, but stronger adularescence translates to higher value: intense blue adularescence is the most valuable, followed by milky white.^{[22]
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Research source} There are numerous factors that contribute to opal pricing, such as play-of-color and pattern. In general, common white opal ranges from $10-$150 per carat, while the Australian black opal starts at $60 per carat.^{[23]
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- Black opals are considered the most rare and valuable type of opal, with some selling up to $10,000 per carat.^{[24]
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Section 6 of 6:

How to Choose the Right Gem

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Choose a moonstone that is free from inclusions. Although it depends on personal preference, most people prefer colorless moonstones that have an intense blue adularescence. Inclusion in a stone refers to anything that breaks the clarity of the stone. Avoid moonstones that have a yellow, green, or brown background tint, and ensure your gem is free from tiny tension cracks (also known as “centipedes”).^{[25]
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Trustworthy Source
Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
Go to source}
- Select a stone that is uniform and rounded: flat moonstones don’t display sheen well and are less valuable.
- If you're looking for a meaningful gift, surprise your loved one with a moonstone pendant or earrings.
2
Evaluate the color, clarity, and pattern of opals. There are endless color choices, but make sure to choose an opal that is rich and vibrant. Translucent or transparent clarity showcases the color and pattern best, but some people prefer opaque opals. In terms of pattern, large, tightly-arranged patches of color are more desirable than small, scattered dots.^{[26]
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Trustworthy Source
Gemological Institute of America
Nonprofit institute responsible for gemological research and education and setting gemstone buying and selling standards
Go to source}
- You can’t go wrong with an opal ring or necklace, but keep in mind that opals turn fuzzy overtime. If you buy an opal ring, you must re-facet it in a few years or replace it entirely.^{[27]
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- It’s important to treat your opal jewelry with care so you can extend its wear-time. To clean opal rings, wet a cloth with warm, soapy water and gently wipe the stone.