What Are Inclusions in Gemstones?

When examining a gemstone closely, you may notice tiny internal features such as:

• Small crystals
• Lines
• Needles
• Bubbles
• Fractures
• Clouds
• Growth patterns

These internal characteristics are commonly known as inclusions.

Inclusions are an important part of gemology because they can provide valuable information about a gemstone's formation, identity, natural or synthetic origin, treatment history, and overall appearance.

Whether you're looking at an Emerald (Panna), Ruby (Manik), Blue Sapphire (Neelam), Yellow Sapphire (Pukhraj), Amethyst, Aquamarine, Tourmaline, Garnet, or another gemstone, inclusions can tell an interesting story about what happened during or after the gemstone formed.

At MithilaShri, we believe understanding gemstone characteristics helps customers make more informed buying decisions.

What Does Inclusion Mean in a Gemstone?

An inclusion is a feature enclosed within a gemstone or present as part of its internal structure.

Inclusions can include:

• Minerals
• Crystals
• Fluids
• Gases
• Internal fractures
• Growth structures
• Needles
• Other natural or artificial features

Some inclusions formed while the gemstone was growing inside the Earth.

Others may have developed later because of geological stress, fractures, or other processes.

In some cases, inclusions can also provide clues about treatments or whether a gemstone may be synthetic.

Are Inclusions Always Bad?

No.

Inclusions are not automatically a sign that a gemstone is poor quality.

In fact, inclusions can sometimes:

• Help identify a gemstone
• Provide clues about natural origin
• Help distinguish natural from synthetic material
• Create special visual effects
• Make a gemstone unique

However, inclusions can also affect a gemstone's:

• Transparency
• Clarity
• Durability
• Appearance
• Market value

The effect depends on the type, size, location, number, and visibility of the inclusions.

How Do Inclusions Form?

Inclusions can form at different stages of a gemstone's history.

During Crystal Growth

As a gemstone forms, small particles, minerals, fluids, or gases can become trapped inside the growing crystal.

Through Geological Activity

Changes in pressure and temperature can create internal stress and fractures.

Through Mineral Interaction

Different minerals can form together, causing one mineral to become enclosed inside another.

Through Fluid Trapping

Small amounts of liquid or gas can become trapped during crystal formation.

Through Later Changes

Some internal features can develop after the gemstone originally formed because of pressure, heat, or geological movement.

Each inclusion can provide clues about the gemstone's history.

Common Types of Inclusions in Gemstones

Inclusions can appear in many different forms.

Some of the most common types include:

• Crystal inclusions
• Needle inclusions
• Fluid inclusions
• Gas inclusions
• Three-phase inclusions
• Fingerprint inclusions
• Feather inclusions
• Growth lines
• Clouds
• Mineral inclusions
• Internal fractures

Let's understand them in more detail.

Crystal Inclusions

A crystal inclusion occurs when another mineral crystal becomes trapped inside the host gemstone.

For example, a small crystal of one mineral may be enclosed inside:

• Emerald
• Ruby
• Sapphire
• Quartz
• Other gemstone materials

These inclusions can sometimes be visible with magnification and may help gemologists identify the gemstone or understand how it formed.

In some cases, identifying the included mineral can provide useful geological information.

Needle Inclusions

Needle inclusions are long, thin, needle-like structures found inside some gemstones.

One well-known example is rutile needles in corundum.

In Ruby and Sapphire, fine rutile needles can sometimes form a pattern that produces a special optical effect known as asterism.

When properly oriented and cut as a cabochon, the gemstone may display a star-like pattern.

This is seen in:

• Star Ruby
• Star Sapphire

In these cases, inclusions can actually contribute to the gemstone's beauty and desirability.

Fluid Inclusions

A fluid inclusion contains liquid trapped inside the gemstone.

These tiny cavities may contain:

• Water
• Other liquids
• Dissolved minerals
• A combination of liquid and gas

Fluid inclusions can provide valuable information about the conditions under which a gemstone formed.

They are often studied under magnification.

Gas Inclusions

Gas inclusions are small cavities containing gas.

Under magnification, they may sometimes appear as bubbles.

However, it is important to remember that a bubble-like appearance does not automatically identify the exact material.

For example, gas bubbles may be associated with certain natural inclusions, while rounded bubbles can also be characteristic of glass or some manufactured materials.

Professional gemological examination considers multiple characteristics before reaching a conclusion.

Three-Phase Inclusions

A three-phase inclusion contains three different components, usually:

• A liquid
• A gas bubble
• A solid crystal

These inclusions are particularly well known in some Emeralds.

Under magnification, a three-phase inclusion may show:

1. Liquid
2. A gas bubble
3. A solid crystal

Such inclusions can provide useful clues during gemological examination.

However, the presence or absence of one particular inclusion should not be treated as absolute proof of a gemstone's origin.

Fingerprint Inclusions

Fingerprint inclusions are patterns of healed fractures containing tiny fluid or mineral-filled features.

They can resemble:

• Fingerprints
• Swirls
• Curved lines
• Interconnected patterns

These inclusions can form when fractures develop and later partially heal under geological conditions.

Fingerprint inclusions are commonly examined using magnification.

Feather Inclusions

A feather is an internal fracture that may have a feather-like appearance.

Depending on its location and orientation, a feather may affect:

• Transparency
• Clarity
• Durability

A small internal feather may have little visible effect.

However, a large fracture reaching the surface may create a greater durability concern.

The location of an inclusion is therefore just as important as its size.

Cloud Inclusions

A cloud consists of many tiny inclusions grouped closely together.

When viewed together, they can create a hazy or cloudy appearance.

Clouds may:

• Reduce transparency
• Affect clarity
• Scatter light
• Influence the overall appearance

The effect depends on how dense and visible the cloud is.

Growth Structures

Gemstones can contain internal patterns created during crystal growth.

These may include:

• Straight growth lines
• Angular patterns
• Color zoning
• Other growth structures

Growth features can provide useful information to gemologists.

Natural and synthetic gemstones may sometimes show different types of internal growth structures, although identification requires professional interpretation.

Mineral Inclusions

A gemstone may contain small pieces or crystals of other minerals.

For example, a natural gemstone may have formed around or alongside another mineral.

These mineral inclusions can sometimes help gemologists understand:

• Geological formation
• Crystal growth
• Possible origin
• Gemstone identity

Some included minerals may even be identifiable under sufficient magnification and testing.

What Are Fractures in Gemstones?

A fracture is a break or separation within a gemstone.

Some fractures may be:

• Internal
• Surface-reaching
• Partially healed
• Filled with another material

Fractures can affect both appearance and durability.

A surface-reaching fracture can be particularly important because it may make the gemstone more vulnerable to damage.

Some gemstones with fractures may undergo treatments such as filling or oiling to improve their apparent clarity.

Inclusions vs Flaws: Are They the Same?

Not exactly.

An inclusion is a broad term for an internal feature.

A flaw is often used more generally to describe a feature considered undesirable because it affects appearance or durability.

Therefore, not every inclusion should automatically be described as a flaw.

For example:

• Rutile needles creating a star effect may be desirable.
• A small mineral crystal may have little impact on appearance.
• A large surface-reaching fracture may be considered a significant clarity or durability issue.

The effect depends on the individual gemstone.

Why Do Natural Gemstones Have Inclusions?

Natural gemstones form under complex geological conditions.

During this process, they may experience:

• Changes in temperature
• Changes in pressure
• Chemical interactions
• Crystal growth interruptions
• Mineral contact
• Fluid movement

These processes can leave behind internal characteristics.

This is one reason natural gemstones often contain unique internal features.

However, a gemstone does not have to contain visible inclusions to be natural.

Some natural gemstones can have very high clarity.

Do Inclusions Prove That a Gemstone Is Natural?

Not always.

Certain inclusion patterns may support a natural-origin conclusion, but the presence of inclusions alone does not automatically prove that a gemstone is natural.

Synthetic gemstones can also contain internal features.

In fact, some synthetic materials may display characteristic growth patterns or inclusions that help gemologists identify their laboratory origin.

Professional identification considers multiple factors, such as:

• Inclusions
• Growth structures
• Refractive index
• Specific gravity
• Spectroscopy
• Fluorescence
• Chemical composition
• Other gemological observations

Can Inclusions Help Identify Synthetic Gemstones?

Yes.

Inclusions and growth patterns can sometimes provide important clues about synthetic origin.

For example, some laboratory-grown gemstones may display:

• Curved growth structures
• Flux-related inclusions
• Gas bubbles
• Metallic particles
• Other characteristic internal features

However, interpretation requires experience.

A single internal feature should not be used alone to make a final conclusion about whether a gemstone is natural or synthetic.

How Gemologists Examine Inclusions

Gemologists commonly use magnification to study internal features.

Tools may include:

• Jeweler's loupe
• Gemological microscope
• Fiber-optic lighting
• Darkfield illumination
• Other specialized lighting techniques

Magnification allows the examiner to observe details that may not be visible to the naked eye.

The type, shape, location, and behavior of an inclusion can provide valuable information.

What Is Darkfield Illumination?

Darkfield illumination is a common lighting technique used in gemological microscopy.

The gemstone is illuminated in a way that can make internal features stand out against a darker background.

This can help reveal:

• Inclusions
• Fractures
• Growth structures
• Other internal characteristics

It is particularly useful when examining transparent or translucent gemstones.

Can You See Inclusions Without a Microscope?

Sometimes.

Large inclusions may be visible with the naked eye.

Smaller features may require:

• A 10× jeweler's loupe
• A microscope
• Proper lighting

However, seeing an inclusion does not automatically mean you can accurately identify it without gemological knowledge.

Different internal features can appear similar under casual observation.

What Is an "Eye-Clean" Gemstone?

An eye-clean gemstone generally means that no inclusions are easily visible to the unaided eye under normal viewing conditions.

However, the term does not necessarily mean the gemstone is completely free of inclusions.

Many eye-clean gemstones still contain internal features that can be seen under magnification.

The exact interpretation of "eye-clean" can also vary depending on the seller or gemstone type.

Do Inclusions Affect Gemstone Clarity?

Yes.

Inclusions are one of the factors that influence clarity.

A gemstone with many visible inclusions may appear:

• Cloudy
• Less transparent
• Less brilliant

A gemstone with fewer or less visible inclusions may appear cleaner.

However, acceptable clarity varies significantly between gemstone types.

For example, inclusions that may be considered undesirable in one gemstone may be relatively common or expected in another.

Do Inclusions Affect Gemstone Value?

They can.

The impact depends on:

• Gemstone variety
• Type of inclusion
• Size
• Number
• Location
• Visibility
• Effect on durability
• Effect on appearance

A highly visible inclusion in the center of a transparent gemstone may reduce its value.

However, some inclusions can increase desirability when they create a distinctive optical effect.

For example, properly oriented needle inclusions can produce a visible star in Star Ruby or Star Sapphire.

Can Inclusions Make a Gemstone More Valuable?

Sometimes.

Inclusions can contribute to unique phenomena such as:

Asterism

A star-like pattern seen in gemstones such as Star Ruby and Star Sapphire.

Chatoyancy

A moving band of light resembling a cat's eye.

Other Visual Effects

Certain internal structures can create distinctive appearances that make a gemstone particularly interesting or desirable.

Therefore, inclusions should not always be viewed negatively.

Inclusions and Asterism

Asterism is the star effect visible in certain gemstones.

It is often associated with properly oriented needle-like inclusions.

When the gemstone is cut into an appropriate cabochon shape, reflected light can produce a star-like pattern across its surface.

Common examples include:

• Star Ruby
• Star Sapphire

The quality of the star can depend on factors such as:

• Sharpness
• Centering
• Visibility
• Symmetry
• Movement

Inclusions and Chatoyancy

Chatoyancy is an optical effect that creates a narrow band of reflected light resembling the eye of a cat.

The effect can occur because of:

• Parallel needle-like inclusions
• Fibrous structures
• Other aligned internal features

Cat's Eye gemstones are commonly cut as cabochons to display this effect.

In such cases, the internal structure is essential to the gemstone's visual character.

Do All Gemstones Have the Same Type of Inclusions?

No.

Different gemstone varieties can have different characteristic inclusions.

For example:

Emerald

May contain:

• Fluid inclusions
• Three-phase inclusions
• Mineral crystals
• Fingerprint-like healed fractures

Ruby and Sapphire

May contain:

• Rutile needles
• Mineral crystals
• Growth structures
• Other internal features

Quartz

May contain:

• Fluid inclusions
• Mineral inclusions
• Needles
• Growth structures

Tourmaline

May contain:

• Tubes
• Needles
• Growth features

These characteristics can help gemologists study and identify gemstones.

Why Inclusion Location Matters

The same inclusion can have a different impact depending on where it is located.

For example:

Near the Edge

An inclusion may be less noticeable.

Under the Table

An inclusion may be more visible when viewing the gemstone from above.

Surface-Reaching

An inclusion or fracture may affect durability.

Therefore, clarity is not simply about how many inclusions are present.

Location and visibility matter too.

Can Treatments Change the Appearance of Inclusions?

Yes.

Some gemstone treatments are designed specifically to improve the appearance of fractures or inclusions.

Examples include:

• Oil treatment
• Resin filling
• Fracture filling
• Glass filling

These treatments can make fractures or internal features less visible.

In some cases, the treatment itself may leave clues that can be detected through gemological examination.

This is another reason treatment disclosure is important when purchasing a gemstone.

Inclusions and Gemstone Durability

Not all inclusions affect durability.

However, certain internal fractures or surface-reaching features may make a gemstone more vulnerable to:

• Chipping
• Cracking
• Breaking

The risk depends on:

• The gemstone material
• Inclusion type
• Size
• Location
• Setting
• Daily wear

A trained jeweler or gemologist may consider these factors when deciding how a gemstone should be mounted.

Should You Avoid Gemstones With Inclusions?

Not necessarily.

The right choice depends on what you are looking for.

You may prefer a gemstone with:

High Clarity

If you want a clean, transparent appearance.

Natural Character

If you appreciate visible internal features.

A Special Optical Effect

If you're interested in Star Ruby, Star Sapphire, Cat's Eye, or other phenomenon gemstones.

The most important thing is understanding how the inclusions affect:

• Appearance
• Durability
• Value
• Care

What Should You Look for When Buying an Included Gemstone?

Before purchasing, consider the following:

1. Visibility

Are the inclusions visible to the naked eye?

2. Location

Are they in a prominent area or near the edge?

3. Durability

Do any fractures reach the surface?

4. Transparency

Do the inclusions significantly reduce transparency?

5. Treatment

Have fractures or inclusions been filled or treated?

6. Certification

For valuable gemstones, check available laboratory documentation.

7. Overall Appearance

Evaluate the gemstone as a complete piece rather than focusing on a single characteristic.

Inclusions and Astrological Gemstones

If you are purchasing a gemstone for traditional astrological purposes, views regarding inclusions and gemstone quality can vary depending on the astrologer or tradition.

Some traditional practices may recommend gemstones with particular visual characteristics.

If you are following an astrological recommendation, discuss the preferred gemstone characteristics with a qualified astrologer.

Traditional astrological gemstone recommendations are based on cultural and astrological beliefs and should not be treated as scientifically proven methods for producing specific outcomes.

How MithilaShri Helps You Understand Gemstone Characteristics

At MithilaShri, we believe that understanding gemstone characteristics can help customers make more informed decisions.

Depending on the product, listings may provide information about:

• Gemstone type
• Carat weight
• Measurements
• Product specifications
• Natural gemstone details
• Certification information where applicable

Understanding inclusions, clarity, treatments, and other gemological properties can help customers evaluate gemstones based on more than appearance alone.

Frequently Asked Questions

What are inclusions in gemstones?

Inclusions are internal features found within a gemstone, such as crystals, fluids, gases, needles, fractures, or growth structures.

Are inclusions always bad?

No. Some inclusions have little effect on appearance, while others can help identify the gemstone or create desirable optical effects.

Do inclusions mean a gemstone is natural?

Not necessarily. Natural gemstones can contain inclusions, but synthetic gemstones can also have characteristic internal features.

Can a gemstone with inclusions still be valuable?

Yes. Value depends on the gemstone type, quality, rarity, appearance, and the nature of its inclusions.

What is an eye-clean gemstone?

An eye-clean gemstone generally has no inclusions that are easily visible to the unaided eye under normal viewing conditions.

Can inclusions affect durability?

Yes. Large or surface-reaching fractures may increase the risk of damage.

What are three-phase inclusions?

They are inclusions containing three components, commonly a liquid, gas bubble, and solid crystal.

What causes the star effect in Star Ruby and Star Sapphire?

Properly oriented needle-like inclusions can create the optical phenomenon known as asterism.

Can inclusions help identify a gemstone?

Yes. Gemologists can study inclusions and growth structures along with other properties to help identify gemstone material and origin.

Can gemstone treatments hide inclusions?

Some treatments, such as oiling, resin filling, or fracture filling, can reduce the visibility of fractures and internal features.

Final Thoughts

Inclusions are more than just marks or imperfections inside a gemstone.

They can provide valuable clues about a gemstone's:

Formation + Identity + Internal Structure + Possible Origin + Treatment History

Some inclusions may reduce clarity or affect durability, while others can create beautiful optical phenomena such as asterism and chatoyancy.

This is why inclusions should always be evaluated in context.

A gemstone with visible inclusions is not automatically poor quality, and a gemstone with very high clarity is not automatically more valuable. The complete evaluation depends on the gemstone variety, appearance, rarity, treatment status, durability, and overall quality.

Whether you're considering an Emerald, Ruby, Blue Sapphire, Yellow Sapphire, Amethyst, Aquamarine, Tourmaline, Cat's Eye, or another gemstone, understanding inclusions can help you appreciate the natural characteristics that make every gemstone unique.

At MithilaShri, we encourage buyers to consider the complete gemstone—including its identity, color, clarity, cut, weight, treatment information, measurements, and available certification—before making a purchase.