Moonstone vs. Rainbow Moonstone: The Difference and Similarities

If you’re a Moonstone enthusiast, you’ve likely encountered this question: Is rainbow moonstone really moonstone?

Rainbow moonstone is transparent labradorite, a closely related feldspar mineral with sheen in a variety of iridescent colors. Although it’s technically not moonstone, it’s similar enough that the trade has accepted it as a gem in its own right. Today some people prefer it to traditional moonstone.

The above is an answer from GIA. Both Moonstone and Rainbow Moonstone are captivating gemstones belonging to the Feldspar family. Although the industry commonly treats them as the same gemstone, they have significant differences in their mineralogical and optical properties. In this article, we will explore the similarities and differences between these two gemstones to help readers better understand and choose the right gemstone.

Moonstone vs. Rainbow Moonstone: Formation and Source

Moonstone: Moonstone primarily comes from Orthoclase and Albite minerals, commonly found in granite and metamorphic rocks. Major sources include Myanmar, India, Sri Lanka, and Tanzania.

Rainbow Moonstone: Rainbow Moonstone forms within the plagioclase mineral, primarily in basic igneous rocks. Important sources include Canada, Finland, Russia, Mexico, and Madagascar.

Moonstone vs. Rainbow Moonstone: Mineralogical Properties

Moonstone’s Mineralogical Properties

• Chemical Composition: Moonstone is a type of Feldspar, composed of Orthoclase and Albite, with the chemical formula (Na,K)AlSi₃O₈. Its captivating optical effect, known as adularescence, is due to the lamellar crystal structure formed by the mixture of Orthoclase and Albite.
• Crystal System: Moonstone has a single axis of symmetry and belongs to the Monoclinic crystal system.
• Crystal Structure: The lamellar structure of Feldspar crystals results in its unique optical effects.

Rainbow Moonstone’s Mineralogical Properties

• Chemical Composition: Rainbow Moonstone is essentially transparent Labradorite, a type of Plagioclase within the Calcium series, with the formula (Ca,Na)(Al,Si)₄O₈. It contains 50-70% Calcium Feldspar and 30-50% Sodium Feldspar.
• Crystal System: Rainbow Moonstone lacks symmetry axes and planes, belonging to the Triclinic crystal system.
• Crystal Structure: While similar to Moonstone, the internal distribution of elements in Rainbow Moonstone creates rainbow-colored light spots.

Moonstone vs. Rainbow Moonstone: Physical Properties

Appearance and Color

Moonstone: Moonstone is a Feldspar with a semi-translucent to opaque base, available in various colors including blue, gray, white, pink, peach, green, and brown, as well as colorless. Its renowned blue-white sheen under light is its primary claim to fame.

Rainbow Moonstone: Rainbow Moonstone is a transparent Feldspar that displays a colorful sheen, typically with a gray base. The diffraction of light within the mineral layers produces various colors such as red, green, and yellow, also known as the play-of-color effect.

Hardness and Durability

Both Moonstone and Rainbow Moonstone have a Mohs hardness of 6-6.5, so their durability is moderate. They should be protected from impact and scratches and require proper care to maintain their luster.

Cleavage and Fracture

Moonstone: Moonstone has good {001} cleavage, allowing it to split smoothly along specific directions due to its lamellar crystal structure. Its fractures are typically conchoidal or uneven because of its layered structure.

Rainbow Moonstone: Rainbow Moonstone also has good {001} cleavage. Its Monoclinic structure results in very clear cleavage planes, contributing to smooth cleavage surfaces. Its fractures are generally conchoidal, caused by its layered structure and crystal defects, and do not present regular planes.

Moonstone vs. Rainbow Moonstone: Optical Effects

Moonstone: The classic optical effect of Moonstone is adularescence (moonlight effect), where light refracts within the gemstone’s lamellar structure, creating a soft white to blue glow. Some Moonstones also display the “cat’s eye effect” or “star effect,” seen as a white flash in the center of the gemstone when light is directed on it, or as a star-like pattern, respectively.

Rainbow Moonstone: Rainbow Moonstone exhibits a variety of optical effects, with its trace elements producing multiple color flashes such as red, green, and yellow, known as the play-of-color or schiller effect. This is due to the more complex crystal structure of Labradorite, which diffracts light into a range of colors.

Moonstone vs. Rainbow Moonstone: Best Cutting Methods

Both Moonstone and Rainbow Moonstone are best cut in a cabochon style, which lacks sharp edges and allows light to be concentrated on the gemstone’s surface, maximizing their optical effects. The “cat’s eye effect” and “star effect” in Moonstone are almost exclusively visible with this cut.

Moonstone vs. Rainbow Moonstone: Metaphysical Meaning

Moonstone: Moonstone symbolizes inner peace, emotional balance, and enhanced intuition, often considered a talisman and feng shui stone. It is believed to have healing properties that improve sleep and emotional well-being.

Rainbow Moonstone: Rainbow Moonstone represents feminine power, personal growth, protection, and energy balance. It is believed to enhance fertility, personal energy, and confidence, and offer comprehensive protection.

Moonstone is suitable for those seeking emotional balance and inner peace. Additionally, Moonstone is one of the birthstones for June and the 13th wedding anniversary gemstone. Rainbow Moonstone is ideal for those seeking multiple energies and protection. The choice should be based on personal needs and beliefs.

Moonstone vs. Rainbow Moonstone: Price and Investment Potential

Moonstone: The price of Moonstone depends on color, optical effects, and purity. High-quality blue Moonstones are more expensive. Its long history and classic appeal contribute to a stable market value.

Rainbow Moonstone: Due to its unique optical effects and rarity, Rainbow Moonstone generally commands higher market prices than Moonstone. Its distinctiveness and colorful effects offer higher market value and investment potential.

Moonstone vs. Rainbow Moonstone: Jewelry Applications

Both Moonstone and Rainbow Moonstone are used in rings, pendants, necklaces, earrings, and bracelets. Different design styles can showcase various effects and uses of the gemstones. For example, large Moonstones are often set in engagement rings, while small Rainbow Moonstones are used in wedding rings. Larger pieces of Moonstone/Rainbow Moonstone are often used in pendants.

How to Choose Between Moonstone and Rainbow Moonstone

Considerations for Choosing Moonstone:

• Purity: Higher-purity Moonstones exhibit stronger optical effects.
• Color: Choose a color that suits personal preference, such as classic blue.
• Optical Effects: Intensity and uniformity of the blue glow.

Considerations for Choosing Rainbow Moonstone:

• Color Uniformity: Uniformity and quality of the rainbow-colored flashes.
• Flash Quality: Variety and brightness of the rainbow flashes.
• Hardness: Ensure the hardness of the Rainbow Moonstone is suitable for daily wear.

Practical Advice: Choose the gemstone based on personal budget and jewelry design needs. Generally, Rainbow Moonstone is more expensive than Moonstone. Moonstone is suitable for classic designs, while Rainbow Moonstone fits unique and modern styles.

Related reading: Moonstone Rings Buying Guide

Final Thoughts

Moonstone and Rainbow Moonstone each have their unique beauty and properties. Moonstone is loved for its classic blue sheen and rich history, while Rainbow Moonstone offers a novel option with its unique play-of-color effect. We hope this detailed comparison helps you select the gemstone that best suits you. MollyJewelryUS offers beautiful Moonstone & Rainbow Moonstone rings, with customization options available. Check them out!