Moonstone is an adularescent feldspar admired for the pale glow that appears to float across its surface. This optical phenomenon, known as adularescence, makes moonstone one of the most recognisable materials used in gemstone jewellery.

Moonstone may be colourless, white, cream, grey, peach, brown or green. The finest transparent examples can display a vivid blue sheen, while other stones show a silvery or white glow.

In this guide, we examine moonstone’s mineral composition, hardness, formation and optical properties. We also explain how genuine moonstone differs from rainbow moonstone, opalite and common imitations.

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What is moonstone?

Moonstone is a gem variety of feldspar defined by its adularescence. Classic moonstone is generally an alkali feldspar in which extremely fine layers of potassium-rich and sodium-rich feldspar interact with light.

It is commonly described as orthoclase containing thin albite layers. However, the commercial name moonstone is also applied to some other feldspars that display a comparable floating glow. For this reason, moonstone is best understood as an adularescent feldspar variety rather than as one universally identical mineral composition.

Moonstone belongs to the feldspar family, one of the most abundant mineral groups in Earth’s crust. Other familiar feldspar gemstones include labradorite, sunstone, amazonite and rainbow moonstone.

To explore its traditional symbolism and everyday uses, read our separate guide to moonstone meaning.

Moonstone composition

Classic moonstone belongs to the alkali feldspar series. It is principally associated with potassium feldspar, commonly orthoclase, and sodium feldspar, or albite.

At high temperatures, these feldspar components can exist together in a more uniform structure. As the material cools, they separate into microscopic intergrowths or lamellae. These fine layers are responsible for moonstone’s characteristic glow.

• Mineral group: feldspar
• Classic host mineral: orthoclase or another potassium-rich feldspar
• Internal layers: commonly albite-rich lamellae
• Main elements: potassium, sodium, aluminium, silicon and oxygen
• Defining optical effect: adularescence

Because the proportions of feldspar components vary, not every moonstone has exactly the same chemical formula or gemmological measurements.

Moonstone properties

• Mineral group: feldspar
• Typical composition: intergrown potassium- and sodium-rich feldspar
• Hardness: approximately 6–6.5 on the Mohs scale
• Lustre: vitreous to pearly
• Transparency: transparent to opaque
• Typical colours: colourless, white, cream, grey, peach, brown and green
• Optical phenomenon: adularescence
• Cleavage: two distinct directions
• Toughness: generally poor
• Common cut: cabochon

How hard is moonstone?

Moonstone has a hardness of approximately 6–6.5 on the Mohs scale. It is softer than quartz gemstones such as amethyst, rose quartz and clear quartz, which have a hardness of around 7.

A hardness of 6–6.5 means moonstone is suitable for jewellery, but hardness only describes resistance to scratching. It does not indicate how easily a stone may chip or break.

Moonstone has two directions of cleavage, along which its crystal structure can separate. A sharp impact can therefore crack the stone even when its surface has resisted ordinary wear.

Pendants and earrings are generally better protected than rings and bracelets. Moonstone rings can still be worn, but a protective setting and careful handling are advisable.

How does moonstone form?

Moonstone’s internal structure develops as feldspar cools. At a high temperature, potassium- and sodium-rich components may be mixed within the same feldspar crystal. As cooling continues, the components become less compatible and begin separating into extremely fine layers.

This process is known as exsolution. It creates alternating microscopic regions with slightly different compositions and refractive properties.

The layers may be comparable in size to wavelengths of visible light. When they are sufficiently fine and correctly arranged, they scatter incoming light and produce adularescence.

Moonstone is commonly associated with igneous rocks and pegmatites in which feldspar crystals had time to grow and cool. It may later be released from its host rock through weathering and collected from secondary deposits.

This formation differs from obsidian, which is volcanic glass produced when silica-rich lava cools too quickly to develop an ordinary crystalline structure.

Why does moonstone glow?

Moonstone’s characteristic glow is called adularescence. It appears as a white, silvery or blue light floating beneath the polished surface of the stone.

The phenomenon occurs when light enters the feldspar and encounters its microscopic internal layers. Part of the light is scattered and reflected between regions with slightly different optical properties.

As the stone or light source moves, the angle of interaction changes. This makes the glow appear to travel across the surface.

Adularescence is an internal optical effect. It is not a surface coating, and it should appear to originate from within a genuine moonstone.

Why does the glow move?

Adularescence is highly directional. The brightness and location of the glow depend on the relationship between:

• the orientation of the internal feldspar layers
• the direction of the light source
• the viewing angle
• the orientation and shape of the cut stone

A moonstone may show a bright flash from one direction and little visible glow from another. Turning the stone under a single light source is one of the best ways to examine its optical effect.

Adularescence and labradorescence

Adularescence and labradorescence are related optical effects found in feldspar, but they are not identical.

Feature	Moonstone	Labradorite
Optical effect	Adularescence	Labradorescence
Typical appearance	Floating white, silvery or blue glow	Distinct blue, green, gold, orange or multicoloured flashes
Usual feldspar group	Most commonly alkali feldspar	Plagioclase feldspar
Common body colour	Colourless, white, peach, grey or cream	Usually grey, charcoal, greenish or pale

Darker labradorite typically displays broad areas of intense colour. Moonstone usually shows a more diffuse glow that appears to float across the stone.

Moonstone and rainbow moonstone

Despite its name, most rainbow moonstone is not traditional alkali-feldspar moonstone. It is generally transparent or white labradorite belonging to the plagioclase feldspar series.

Rainbow moonstone may display strong blue, green, gold and violet flashes. Traditional moonstone more often shows a floating white, silvery or blue sheen.

Feature	Traditional moonstone	Rainbow moonstone
Usual classification	Adularescent alkali feldspar	Pale or transparent labradorite
Feldspar series	Typically potassium–sodium feldspar	Plagioclase feldspar
Optical appearance	Floating white or blue glow	Blue or multicoloured flashes
Commercial name	Moonstone	Rainbow moonstone or white labradorite

Both are genuine feldspar materials, but accurate product descriptions should explain the distinction.

Read more in our guide to rainbow moonstone meaning.

Moonstone colours

Moonstone occurs in a broader range of body colours than its name might suggest. Common varieties include:

• Colourless moonstone: transparent or nearly transparent material
• White moonstone: a pale body with white, silver or blue adularescence
• Peach moonstone: peach, pinkish or pale orange material
• Grey moonstone: a light to dark grey body with a silvery sheen
• Brown moonstone: beige, tan or brown feldspar showing adularescence
• Green moonstone: pale green material with a white or silvery glow

Body colour and optical effect are separate features. A peach moonstone, for example, describes the underlying colour rather than the colour of its adularescence.

What is blue moonstone?

Blue moonstone usually refers to transparent or nearly colourless moonstone displaying a strong blue adularescence. Fine specimens can show an intense blue light that moves broadly across the face of the stone.

Blue moonstone is not necessarily a separate mineral variety. The name describes the appearance and quality of its optical effect.

Stones with high transparency, an inconspicuous body colour and a bright blue sheen are particularly valued in the gem trade.

Peach moonstone and other commercial names

Commercial moonstone names commonly describe body colour or appearance rather than formal mineral species. Examples include peach moonstone, grey moonstone, black moonstone and blue moonstone.

“Black moonstone” may refer to dark grey or brown feldspar showing a pale sheen. Material sold under this name should not automatically be assumed to have one exact mineral composition.

Asking for the material’s gemmological identity and possible treatments is worthwhile when precise classification matters.

Where is moonstone found?

Important moonstone sources have included:

• Sri Lanka
• India
• Myanmar
• Madagascar
• Tanzania
• Brazil
• the United States

Sri Lanka is particularly known for transparent moonstone with blue adularescence. India supplies a wide range of moonstone colours and qualities, including material used in beads and carvings.

Geographic origin cannot usually be confirmed from appearance alone. Reliable origin determination may require laboratory testing and supporting documentation.

How is moonstone cut?

Moonstone is most often cut as a cabochon: a rounded, polished shape without conventional facets. The domed surface helps display adularescence and allows the glow to move as the stone is turned.

Correct orientation is essential. A cutter must position the feldspar layers so that the strongest optical effect appears through the top of the finished stone.

If the rough material is cut at an unsuitable angle, a potentially strong sheen may appear weak, restricted to one side or disappear from the face-up view.

Moonstone can also be fashioned into beads, carvings and occasionally faceted gemstones. Faceting is generally used when the material is sufficiently transparent and its optical effect remains attractive.

How is moonstone quality evaluated?

Moonstone quality is assessed through a combination of body colour, transparency, adularescence, clarity, cutting and size.

Body colour

For classic fine moonstone, a colourless or nearly colourless body is often preferred because it allows blue adularescence to stand out clearly. Peach, grey, green and brown moonstones are evaluated according to their own appearance rather than against the colourless ideal.

Adularescence

A bright, mobile sheen covering a broad area of the stone is generally more desirable than a weak effect visible only from a narrow angle. Blue adularescence is especially prized, although attractive white and silvery effects are also popular.

Transparency and clarity

Transparent material can display an especially vivid floating glow. However, inclusions and internal textures are common in moonstone and may contribute to the individuality of a piece.

Cut and orientation

A well-oriented cabochon displays its strongest sheen in the face-up position. The dome should be proportioned so the optical effect can travel across the stone.

Size

Moonstone occurs in many sizes. Large specimens with strong adularescence, good transparency and few distracting fractures are less common than ordinary commercial material.

Common moonstone inclusions

Moonstone may contain fine fractures, needles, mineral inclusions and internal textures produced by its feldspar structure.

One characteristic inclusion is sometimes described as a centipede. It consists of short, fine stress cracks intersecting a longer fracture and may resemble the legs of a centipede under magnification.

Inclusions do not automatically make a moonstone unsuitable. Their effect on appearance, durability and value depends on their size, position and visibility.

Surface-reaching fractures deserve particular attention because they may increase the risk of damage during wear or cleaning.

Is moonstone a birthstone?

Moonstone is one of the traditional birthstones associated with June, alongside pearl and alexandrite. It is also sometimes given for anniversaries and occasions involving new beginnings.

Birthstone associations are cultural traditions rather than mineralogical properties. Anyone can wear moonstone regardless of birth month or zodiac sign.

Moonstone in jewellery

Moonstone is used in pendants, earrings, bracelets and rings. Its moving sheen is particularly visible in jewellery because the stone changes angle as the wearer moves.

Pendants and earrings are practical choices because they are less likely to strike hard surfaces. Rings require more care and benefit from settings that protect the stone’s edges.

When selecting moonstone jewellery, examine:

• whether the glow is visible in the normal wearing position
• how widely the sheen travels across the stone
• whether fractures reach the surface
• whether the setting protects the stone
• whether treatments or composite construction have been disclosed

Explore moonstone jewellery and polished stones

How can you identify genuine moonstone?

Genuine moonstone should display an optical effect that appears to originate within the material and changes as the stone is tilted. Its sheen is normally directional rather than equally bright from every angle.

Features commonly observed in moonstone include:

• a floating white, silvery or blue glow
• directional adularescence
• a transparent, translucent or opaque feldspar body
• fine internal layers or characteristic inclusions
• a vitreous to pearly surface lustre

Visual inspection alone cannot always confirm identity. A gemmologist may examine refractive index, birefringence, specific gravity, inclusions and optical behaviour to distinguish moonstone from similar materials.

Moonstone, opalite and glass

Opalite is a manufactured glass commonly sold as a decorative or jewellery material. It can display a bluish glow against a pale background and an orange appearance when viewed through transmitted light.

Opalite’s appearance is caused by properties of the manufactured glass rather than by feldspar layers and adularescence. It is not moonstone.

Feature	Moonstone	Opalite
Material	Feldspar	Manufactured glass
Optical appearance	Directional floating adularescence	General bluish translucence and orange transmitted colour
Structure	Crystalline	Amorphous glass
Common internal features	Layers, cleavage features and mineral inclusions	May contain rounded gas bubbles

Both materials can be attractive, but they should be labelled accurately.

Can moonstone be treated or imitated?

Glass, synthetic spinel, coated material and assembled stones may imitate moonstone’s appearance. Composite stones can also be constructed by joining separate layers to create or enhance a visible sheen.

Some moonstones may be treated or stabilised to improve their appearance or durability. Treatments should be disclosed by the seller.

Warning signs of imitation may include:

• perfectly uniform glow in every stone
• rounded gas bubbles typical of glass
• colour concentrated only on the surface
• a visible joining line between assembled layers
• an optical effect that does not move naturally with the viewing angle

These observations are not conclusive on their own. Professional gemmological testing is the best option for valuable or uncertain material.

How to care for moonstone

Moonstone needs careful handling because its cleavage and poor toughness make it more vulnerable to breaking than its hardness alone suggests.

• Clean it with lukewarm water, mild soap and a very gentle brush or cloth.
• Rinse briefly and dry it thoroughly.
• Do not use steam cleaners.
• Avoid ultrasonic cleaning.
• Protect it from high heat and sudden temperature changes.
• Keep it away from acids, bleach and abrasive cleaners.
• Store it separately in a padded box or fabric pouch.
• Remove moonstone jewellery before exercise, bathing and household work.

High heat may crack moonstone, while sharp impacts can cause it to split along its cleavage planes.

Can moonstone go in water?

Brief cleaning with lukewarm water is generally suitable for solid, untreated moonstone. Prolonged soaking is unnecessary and should be avoided, especially when the stone contains fractures or is mounted in jewellery.

Do not expose moonstone to very hot or very cold water. Sudden temperature changes can place stress on the material and increase the risk of cracking.

Moonstone should not be placed in drinking water or used to prepare crystal elixirs. Decorative and symbolic use does not require ingestion.

Moonstone meaning in crystal traditions

In crystal traditions, moonstone is associated with intuition, emotional reflection, new beginnings and periods of change. These interpretations belong to spiritual and cultural practices rather than mineral science.

Similar symbolic themes are connected with labradorite, amethyst and rainbow moonstone.

Moonstone has no scientifically established ability to regulate hormones, improve fertility, support pregnancy or treat emotional or physical conditions. It may be kept as a personal symbol, but it should never replace professional healthcare.

Summary of moonstone properties

• Moonstone is an adularescent feldspar gemstone.
• Classic moonstone is commonly associated with orthoclase and fine albite-rich layers.
• Its hardness is approximately 6–6.5 on the Mohs scale.
• It has two cleavage directions and relatively poor toughness.
• Its floating glow is called adularescence.
• Adularescence forms when light scatters through microscopic feldspar layers.
• Moonstone can be colourless, white, peach, grey, brown or green.
• Rainbow moonstone is generally pale labradorite rather than traditional moonstone.
• Warm soapy water is the safest ordinary cleaning method.

Frequently asked questions about moonstone

Is moonstone a mineral?

Moonstone is a gem variety of feldspar defined by its adularescence. Classic moonstone is generally an alkali feldspar containing microscopic layers with different feldspar compositions.

What is moonstone made of?

Classic moonstone is usually associated with potassium-rich feldspar such as orthoclase and fine sodium-rich albite layers. Other adularescent feldspars may also be marketed as moonstone.

How hard is moonstone?

Moonstone has a hardness of approximately 6–6.5 on the Mohs scale.

Is moonstone durable?

Moonstone resists some everyday scratching, but its cleavage gives it poor toughness. It can chip or split if struck against a hard surface.

Why does moonstone glow?

Its glow is caused by adularescence. Light scatters between microscopic feldspar layers and appears to float across the stone as the viewing angle changes.

What colour is moonstone?

Moonstone may be colourless, white, cream, peach, grey, brown or green. Its adularescence is commonly white, silvery or blue.

Is rainbow moonstone real moonstone?

Rainbow moonstone is a genuine feldspar material, but it is usually pale or transparent labradorite rather than traditional alkali-feldspar moonstone.

Is opalite the same as moonstone?

No. Opalite is manufactured glass, while moonstone is crystalline feldspar displaying adularescence.

Can moonstone be worn every day?

Yes, with care. Pendants and earrings are less exposed to impacts than rings and bracelets. Remove moonstone jewellery during exercise, cleaning and other strenuous activities.

How should moonstone be cleaned?

Use lukewarm water, mild soap and a gentle cloth or brush. Avoid steam, ultrasonic cleaning, high heat and sudden temperature changes.

Where is moonstone found?

Important sources have included Sri Lanka, India, Myanmar, Madagascar, Tanzania, Brazil and the United States.

Explore moonstone

Moonstone is an adularescent feldspar valued for the light that appears to float beneath its surface. Its layered internal structure, varied colours and directional glow make every piece different.

Whether you are interested in mineralogy, jewellery or moonstone’s traditional symbolism, understanding its composition and cleavage will help you choose and care for it appropriately.

Explore moonstone jewellery and polished stones