Which Inclusions Reduce Gemstone Durability? Types and Risks

A gemstone beauty is clearly visible, but its durability can’t. Look at two gemstones, which are identical in color and clarity, yet one stone lasts longer than the other. The actual reason lies in something, which you can’t see—its gemstone inclusions. 

Inclusions in gemstones are natural, forming during the process inside the Earth. Some of them are harmless and even show whether a gem is natural or not. While other acts as its weak points that reduce its durability. Therefore, understanding the difference is essential before buying any gemstone for daily wear or astrological purposes. 

In this blog, we will know which inclusion reduces gemstone durability, how gemologists find out, and tips for buyers before making a purchase. 

What Are Gemstone Inclusions?

Gemstone inclusions are natural materials or structural features that take place inside a gem formation process. This inclusion developed due to temperature change, pressure, and mineral composition over millions of years. There are some common inclusions that include: 

• Mineral crystals
• Feather inclusions
• Rutile silk
• Fluid inclusions
• Fingerprint patterns
• Growth tubes
• Cavities
• Color zoning

These features are known as the gemstone natural fingerprint because none of two natural stones has the exact same internal pattern. Therefore, gemologists use inclusions to identify whether it's a natural or synthetic gemstone. 

Which Inclusions Reduce Gemstone Durability the Most?

Some inclusions interrupt the crystal structure, making the gemstone less resistant to everyday wear. Below are the inclusions buyers should pay the closest attention to.

1. Surface-Reaching Fractures

The surface-reaching fractures are known as the biggest threats for gemstone durability. These fractures extend from inside the stone to its surface and expose the crystal to its external stress. 

They can:

• It increases the chance of chipping of gemstone 
• This inclusion expands after accidental impacts
• The gemstone starts collecting dirt and moisture
• It makes jewelry setting more difficult

If a fracture is located near the girdle, corners, or pointed tips, the risk becomes higher because these areas experience most pressure while wearing. 

Risk Level: High

Read more: The Secret Life of Emerald Inclusions and Role

2. Feather Inclusions

Feathers are internal fractures that appear white and feather-like under magnification.

A small feather completely enclosed within the gemstone is often stable. The large-sized feathers can affect the stone if they: 

• If they reach the gemstone surface
• If they get extended across a large area
• If it follows the gemstone's natural cleavage direction
• If they are positioned near edges or corners

Gemologists carefully examine feather inclusions in diamonds, rubies, and sapphires because their location often determines whether the gemstone is suitable for everyday jewelry.

Risk Level: Medium to High

3. Cleavage Cracks

Some gemstones naturally split along specific crystal directions known as cleavage planes. Cracks that develop along these planes significantly reduce durability.

Gemstones with noticeable cleavage include:

• Diamond
• Topaz
• Tanzanite
• Fluorite

This explains why hardness and durability are different. 

Risk Level: High

4. Open Fissures

The open fissures are like narrow cracks connected to the stone surface. This takes place in emeralds and often in treated stones with oil or resin that improve gem appearance. Although these treatments help stone to look cleaner, sometimes they also reduce strength. 

Open fissures may:

• If it traps moisture and dust in stone
• It becomes more visible over time
• This stone requires gentle cleaning
• Always be sensitive to heat during jewelry repairs

Always ask whether an emerald or other gemstone has undergone clarity enhancement before purchasing.

Risk Level: Medium to High

5. Dense Fracture Networks

A single fracture isn't always a problem, but multiple interconnected fractures can weaken the gemstone considerably.

Instead of distributing force evenly, the crystal develops several stress points that make it more likely to:

• Chip during impact
• Crack while being set
• Lose durability over time

Professional gemologists often reject gemstones with extensive fracture networks for rings because they experience the highest daily wear.

Risk Level: High

Quick Comparison: Harmful vs. Harmless Inclusions

Inclusion Type	Impact on Durability
Surface-reaching fracture	High
Cleavage crack	High
Dense fracture network	High
Large feather inclusion	Medium to High
Open fissure	Medium to High
Tiny enclosed crystal	Low
Rutile silk	Low
Color zoning	Cosmetic only

Buyer Tip: Don't judge a gemstone by how many inclusions it has. A single surface-reaching fracture can reduce durability far more than several harmless enclosed inclusions.

Which Gemstone Inclusions Are Usually Harmless?

Not every inclusion is a warning sign. Many natural inclusions have little or no effect on a gemstone's durability and are considered normal in high-quality natural stones. In fact, these features often help gemologists confirm a gemstone's authenticity.

Here are some inclusions that are generally stable:

• Tiny mineral crystals: Fully enclosed crystals rarely weaken the gemstone.
• Rutile silk: Fine needle-like inclusions commonly found in natural rubies and sapphires. They usually affect appearance rather than strength and can even create the star effect in star gemstones.
• Fingerprint inclusions: These are healed fractures that naturally sealed during crystal growth, making them much more stable than open cracks.
• Color zoning: Uneven color distribution changes a gemstone's appearance but doesn't reduce its structural strength.
• Small fluid inclusions: Tiny liquid or gas pockets are common and usually harmless unless associated with large fractures.

The presence of these inclusions shouldn't discourage you from buying a gemstone. Instead, focus on whether they compromise the crystal's structure.

Read more: Identify Cracks and Inclusions in a Gemstone

How Do Gemologists Assess Dangerous Inclusions?

Gemologists don't judge a gemstone based on the number of inclusions alone. They carefully evaluate how each inclusion affects the gemstone's overall durability.

The key factors include

• Location: Inclusions near the girdle, corners, or pointed tips are more vulnerable to damage.
• Size: Larger fractures weaken the crystal more than tiny enclosed inclusions.
• Direction: Cracks following natural cleavage planes are more likely to cause breakage.
• Surface connection: Surface-reaching inclusions create greater structural weakness than enclosed ones.
• Intended use: A gemstone for a ring needs higher toughness than one set in earrings or a pendant.

This detailed evaluation explains why two gemstones with similar clarity grades may have very different durability.

Know more: How Gemologists Verify Natural Gemstones

Which Gemstones Are Most Affected by Structural Inclusions?

Every gemstone has unique physical properties, so the same inclusion may affect different gemstones in different ways.

Gemstone	Common Durability Concern
Emerald	Surface-reaching fractures and open fissures
Diamond	Cleavage-related cracks
Topaz	Perfect cleavage planes
Tanzanite	Cleavage fractures
Ruby	Large feathers near the surface
Sapphire	Extensive surface fractures
Opal	Natural crazing and dehydration cracks

For example, inclusions are expected in natural emeralds, so their presence alone doesn't indicate poor quality. However, a similar fracture in topaz or diamond deserves greater attention because these gemstones are more susceptible to cleavage-related damage.

Tips for Choosing a Durable Natural Gemstone

Before buying a gemstone, follow these practical tips to avoid costly mistakes:

• Buy a certified natural gemstone from a trusted seller.
• Ask whether the gemstone has been fracture-filled, oiled, or resin-treated.
• Examine the gemstone under 10× magnification whenever possible.
• Avoid large surface-reaching fractures near edges and corners.
• Consider toughness and crystal structure, not just Mohs hardness.
• Choose protective settings, such as bezel settings, for relatively fragile gemstones.
• If durability is your priority, ask a gemologist to evaluate the stone before purchase.

A gemstone doesn't need to be flawless to last for decades—it simply needs stable inclusions that don't weaken its structure.

Conclusion

Understanding which inclusions reduce gemstone durability helps you choose a gemstone that is not only beautiful but also built to last. While inclusions are a natural part of a gemstone's formation, only certain types—such as surface-reaching fractures, cleavage cracks, open fissures, and dense fracture networks—significantly weaken its structure.

On the other hand, rutile silk, tiny mineral crystals, fingerprint inclusions, and color zoning are usually harmless and often serve as evidence of a gemstone's natural origin.

Instead of looking for a perfectly flawless gemstone, focus on its overall durability, crystal structure, and clarity characteristics. A certified natural gemstone with stable inclusions can offer exceptional beauty, reliable performance, and long-term value, making it a smarter investment for everyday wear and future generations.