Opal vs. Moonstone: What’s The Difference?

If you like opals, then you'll definitely also like moonstones. At first glance, these two gemstones have a somewhat similar appearance, both exuding an unknown sense of mystery, making them stand out among a pile of gemstones. Today, let's analyze the differences between these two gemstones together.

What Is the Difference Between an Opal and a Moonstone?

Chemical Composition

Opal

Opal's chemical composition is a non-crystalline hydrated form of silica (SiO2·n H2O).

Moonstone

Moonstone, also known as hecatolite, has a chemical composition of sodium potassium aluminum silicate ((Na,K)AlSi3O8) and is a type of feldspar mineral.

Formation

Opal

The formation process of opal is rather complex, typically precipitating from silica-rich water solutions under low-temperature conditions. The scattering of light by water during the precipitation process gives opal its unique colors and optical effects.

Moonstone

Moonstone is composed of tiny columnar mineral crystals within feldspar minerals. The moonlight effect is caused by these tiny mineral crystals forming an optical effect inside the gemstone.

Origin

Opal

Over 95% of opals come from Australia, making opal the "national gemstone" of Australia. Apart from Australia, Ethiopia, Mexico, and others are also major sources of opals.

Moonstone

The primary source of moonstones is Sri Lanka, with others coming from Brazil, India, Australia, Myanmar, China, etc., making moonstones more plentiful in origin compared to opals. Historically, the highest quality moonstones come from Myanmar. 

Appearance

Opal

Opals come in various colors, including white, black, gray, red, orange, green, blue, pink, and purple. High-quality opals exhibit iridescence, hence also known as rainbow opals, which is their unique feature.

If you're planning to buy a colorful ring, then an opal ring will surely fulfill your vision.

Moonstone

Moonstones typically display a milky white to light blue color, known as the "moonlight effect" or "cat's eye effect," which is a unique feature of moonstones.

Mohs Hardness (Durability)

Opal

Opal has a Mohs hardness of 5.5-6.5, making it relatively fragile.

Moonstone

Moonstone has a Mohs hardness of 6-6.5, slightly higher than opal, but both gemstones are relatively fragile and require careful maintenance.

Rarity

Opal

Opal's rarity is reflected in its appearance, where white, gray, and green opals are more common, while fire opals and black opals are relatively rare.

In analyzing the rarity of opals, it's not just about the base color but also about the iridescent colors they exhibit. Blue and green are more common, while pink, red, and yellow are rarer.

Moonstone

The rarity of moonstones is reflected in the size of the stones. Small moonstones are common, but large ones are extremely rare.

Meaning

Opal

Opals exhibit iridescence, resembling rainbows, so they're also considered the "stone of luck." It is believed that wearing opal jewelry can bring good luck, and they also symbolize hope and loyalty, representing happiness.

Moonstone

Moonstones symbolize health, wealth, and longevity. It is said that wearing moonstones can promote sleep and soothe emotions. Moonstones also represent love and are therefore often used in engagement rings.

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Opal & Moonstone FAQs

Which Should You Choose, Opal or Moonstone? Which Is Better?

The choice is yours.

If you prefer a more unique gemstone, then opal would be more suitable. If you prefer a gemstone with a more mysterious aura, then moonstone would be better.

Is Opal and Moonstone Suitable for an Engagement Ring?

Certainly, any gemstone is suitable for an engagement ring, including opals and moonstones, but since these gemstones have relatively low Mohs hardness, they require more careful daily care.

Which Is More Expensive, Opal or Moonstone?

Generally, opals are more expensive than moonstones because opals are rarer to find than moonstones. In special cases, such as an extremely rare blue moonstone compared to a particularly rare red opal, both would be priceless.

Which Is More Durable, Opal or Moonstone?

Moonstone. Because moonstone has a higher Mohs hardness (6-6.5), it is more durable.