Natural Diamond Inclusions: Flaws or Unique Characteristics?

When people begin shopping for a natural diamond, the word “inclusion” can sound like a warning. It is often treated as another word for flaw—something undesirable that should be avoided at all costs.

That interpretation misses an important part of what makes natural diamonds extraordinary.

Natural diamonds formed deep within the Earth under immense heat and pressure, typically between one and three billion years ago. As each diamond crystal developed, it recorded small traces of that geological journey. Tiny crystals, wisps, feathers, clouds, and other internal features became part of the stone’s individual identity.

These characteristics are called inclusions. They can affect a diamond’s clarity grade and value, but they are not automatically defects. Many are visible only under magnification and have no meaningful effect on the diamond’s beauty, brilliance, or durability.

In the right natural diamond, inclusions are better understood as identifying characteristics: a geological fingerprint created by nature and impossible to duplicate exactly.

At Mervis Diamond Importers, we help clients look beyond a clarity grade to understand what the inclusions actually mean, whether they can be seen, and whether they should influence the purchase.

What Are Natural Diamond Inclusions?

Inclusions are internal characteristics found within a diamond. Some formed as the diamond crystal grew within the Earth, while others resulted from the enormous pressures it experienced during its formation and journey toward the surface.

Common inclusions may appear under magnification as:

  • Tiny crystals

  • Pinpoints

  • Clouds

  • Feathers

  • Needles

  • Internal graining

  • Twinning wisps

  • Knots

  • Cavities

External characteristics are generally called blemishes. These may include scratches, abrasions, extra facets, polish lines, or natural surface features left during cutting.

Together, inclusions and blemishes determine a diamond’s clarity grade.

According to the Natural Diamond Council, these characteristics can help reveal the diamond’s individual history. Because natural diamonds formed independently under constantly changing geological conditions, no two carry precisely the same combination of features.

Are Diamond Inclusions Flaws?

Not necessarily.

The word “flaw” implies that something is defective or unsuitable. Most natural diamond inclusions do not meet that description.

An inclusion matters primarily when it:

  • Can be seen without magnification

  • Distracts from the diamond’s appearance

  • Reduces transparency or brilliance

  • Creates a durability concern

  • Is positioned prominently beneath the table

  • Significantly affects rarity or market value

Many natural diamonds in the VS and SI clarity ranges contain inclusions that are difficult or impossible to see with the unaided eye. These stones may look completely clean when worn, even though a trained grader can locate their inclusions under 10× magnification.

In that situation, the inclusion is a grading characteristic rather than a visible defect.

Inclusions Are Part of a Natural Diamond’s Story

A natural diamond is not manufactured to predetermined specifications. It is an ancient material shaped by nature over an almost unimaginable amount of time.

Its inclusions are physical records of that formation.

A small crystal trapped inside the diamond may be a mineral that existed while the diamond was growing. Internal graining can reflect changes in the crystal’s growth. A feather may indicate stress experienced within the Earth.

These characteristics connect the finished engagement ring to the natural diamond’s geological origin.

This does not mean every heavily included diamond is desirable. Beauty and durability still matter. However, it does mean that a microscopic inclusion should not automatically be treated as something negative.

Natural rarity is rarely synonymous with laboratory perfection. In many cases, the characteristics created by nature are part of what makes the gem authentic, individual, and meaningful.

Can Inclusions Prove That a Diamond Is Natural?

Inclusions can provide gemologists with useful information, but an inclusion alone does not prove that a diamond is natural.

Laboratory-grown diamonds can also contain internal growth features, metallic remnants, graining, or other identifying characteristics associated with their manufacturing processes. Experienced gemologists and independent laboratories use specialized instruments, growth-pattern analysis, spectroscopy, fluorescence imaging, and other tests to determine origin.

When buying a natural diamond, always request an independent grading report from a respected laboratory such as GIA. The report should clearly identify the stone as a natural diamond and document its important quality characteristics.

A trusted jeweler can also match the report number or laser inscription to the diamond and explain the documentation before you purchase.

How Diamond Clarity Is Graded

Diamond clarity evaluates the relative absence of inclusions and blemishes.

A trained grader examines the diamond under controlled conditions at 10× magnification and considers five primary factors:

Size

Larger characteristics generally have more influence on the clarity grade than smaller ones.

Number

Several inclusions may have more impact than a single inclusion, although number alone does not determine the grade.

Position

An inclusion directly beneath the center of the table may be more noticeable than one near the girdle or hidden beneath a facet.

Nature

The grader considers what type of characteristic is present and whether it is internal, external, surface-reaching, or potentially related to durability.

Relief

Relief describes how strongly the inclusion contrasts with the surrounding diamond. A dark crystal may be more visible than a translucent feather of a similar size.

These factors are evaluated together. That is why two natural diamonds with the same clarity grade may look different and require individual inspection.

Understanding the Natural Diamond Clarity Scale

The GIA clarity scale contains 11 grades divided among six general categories.

Flawless

FL: No inclusions or blemishes are visible to a skilled grader at 10× magnification.

Flawless natural diamonds are exceptionally rare. Their value reflects that rarity, even though they may not appear different to the naked eye from diamonds in lower clarity categories.

Internally Flawless

IF: No internal inclusions are visible at 10× magnification, although minor surface blemishes may be present.

These natural diamonds are also extremely rare and generally carry a significant premium.

Very, Very Slightly Included

VVS1 and VVS2: Inclusions are extremely difficult for a skilled grader to locate at 10× magnification.

VVS natural diamonds offer exceptional clarity. Their inclusions are generally far too small to be seen without magnification.

Very Slightly Included

VS1 and VS2: Minor inclusions are visible under 10× magnification but are typically difficult to see with the unaided eye.

For many buyers, VS natural diamonds offer an appealing balance of rarity, beauty, and value.

Slightly Included

SI1 and SI2: Inclusions are noticeable to a skilled grader at 10× magnification.

Many SI1—and some carefully selected SI2—natural diamonds can appear eye-clean. The exact type, size, color, and position of the inclusions become especially important in this range.

Included

I1, I2, and I3: Inclusions are obvious under magnification and may be visible without it. Inclusions at these grades may affect transparency, brilliance, or durability.

These diamonds require careful professional evaluation, especially when intended for an engagement ring that will be worn every day.

What Does “Eye-Clean” Mean?

An eye-clean diamond has no inclusions that are readily visible to the unaided eye when viewed face-up under normal conditions.

However, “eye-clean” is not an official laboratory grade. Different sellers may use different viewing distances, lighting, and definitions.

When evaluating whether a natural diamond is eye-clean, consider:

  • Can you see the inclusion without a loupe?

  • Is it visible face-up or only from the side?

  • Is it noticeable from a normal viewing distance?

  • Does it become visible only after someone shows you where to look?

  • Does it appear under ordinary lighting or only intense inspection lighting?

  • Will a prong safely conceal it once the diamond is set?

The Natural Diamond Council notes that eye-clean diamonds are often found in the VS2 to SI1 range, although every stone should be assessed individually.

A carefully selected eye-clean natural diamond may allow you to avoid paying for a clarity grade that cannot be appreciated without magnification. That can leave more of your budget available for cut, carat weight, or a preferred setting.

Common Types of Natural Diamond Inclusions

Understanding common inclusions can make a grading report feel less intimidating.

Crystal

A crystal is a mineral enclosed within the diamond. It may appear colorless, white, dark, red, green, or another color depending on its composition.

A small crystal near the edge may have little effect on beauty. A dark crystal under the center of the table may be more noticeable.

Pinpoint

A pinpoint is an extremely small crystal that appears as a tiny dot under magnification. A single pinpoint usually has little effect on appearance.

Cloud

A cloud is a grouping of pinpoints too small to be identified individually. A small, localized cloud may be harmless, while a large or dense cloud can sometimes reduce transparency.

If a grading report lists “clarity grade based on clouds not shown,” the diamond deserves careful visual evaluation to ensure it remains bright and transparent.

Feather

A feather is an internal separation that may look white or feathery under certain lighting.

Many feathers are small and pose no meaningful concern. Larger, deeper, or surface-reaching feathers near a vulnerable edge may require closer examination for durability.

Needle

A needle is a long, thin crystal that resembles a tiny rod under magnification. Its influence depends on its size, position, color, and visibility.

Internal Graining

Internal graining appears as lines, curves, or hazy areas caused by irregular crystal growth. It can be transparent, reflective, colored, or visible only under particular lighting.

Twinning Wisp

A twinning wisp is a series of inclusions formed when the diamond changed growth direction. It may include tiny crystals, pinpoints, clouds, or graining arranged in a wavy pattern.

Knot

A knot is an included crystal that reaches the polished surface of the diamond. Its importance depends on its size and location.

Cavity

A cavity is an opening on the diamond’s surface, often created when part of an included crystal was removed during polishing.

Small cavities may have limited impact, while larger cavities can collect debris or create durability and maintenance concerns.

Do Inclusions Affect a Diamond’s Sparkle?

Inclusions do not create sparkle. Cut quality is the primary factor controlling how effectively a diamond returns light.

Many minor inclusions have no visible effect on brilliance. A well-cut VS2 or SI1 natural diamond may sparkle more beautifully than a poorly cut diamond with a much higher clarity grade.

Inclusions become more likely to affect sparkle when they are:

  • Large

  • Numerous

  • Dense

  • Dark and centrally located

  • Spread throughout the diamond

  • Significant enough to reduce transparency

A heavily clouded diamond, for example, may appear hazy or sleepy. This is different from a bright, eye-clean diamond containing one small inclusion that can be seen only under magnification.

The grading report helps identify characteristics, but seeing the natural diamond in person reveals whether they affect its actual beauty.

Can Inclusions Affect Durability?

Some inclusions can create durability concerns, but most do not.

Diamonds are exceptionally hard and resist scratching, but hardness is not the same as toughness. A diamond can still chip if struck at a vulnerable point or along certain internal features.

Characteristics that deserve closer evaluation include:

  • Large feathers reaching the surface

  • Cavities near an edge

  • Inclusions extending through a corner

  • Significant inclusions near the girdle

  • Weak points in pointed shapes

  • Inclusions affecting structural integrity

Diamond shapes with pointed corners—such as princess, pear, marquise, and heart shapes—require protective settings regardless of clarity. A professional should evaluate any inclusion near these vulnerable areas.

A qualified jeweler can determine whether a characteristic is merely visible under magnification or presents a practical concern for everyday wear.

Does Diamond Shape Affect How Visible Inclusions Are?

Yes. Facet style can make inclusions easier or more difficult to see.

Brilliant-Cut Diamonds

Round, oval, pear, cushion, marquise, radiant, and princess-cut diamonds use complex facet patterns that create abundant sparkle. This light movement can help conceal some inclusions.

A carefully selected SI1 natural diamond in a brilliant cut may appear eye-clean.

Step-Cut Diamonds

Emerald and Asscher-cut diamonds have broad, open facets that create a hall-of-mirrors effect. Their large windows make internal characteristics easier to see.

Buyers often choose a higher clarity grade for step cuts, although the correct grade still depends on the specific diamond.

Larger Diamonds

Inclusions may become easier to see as diamond size increases. A clarity grade that appears eye-clean in a one-carat diamond may be more visible in a three- or four-carat stone.

This is another reason clarity should be evaluated in the context of shape, size, and cut—not as an isolated letter-and-number grade.

Do Higher-Clarity Natural Diamonds Always Look Better?

No.

Higher clarity means the diamond has fewer or less noticeable clarity characteristics under magnification. It does not automatically mean the diamond has better sparkle.

Cut quality has a much greater impact on brilliance. Color, shape, proportions, and personal preference also influence beauty.

A VVS natural diamond may be rarer and more valuable than a VS2 natural diamond, but both may appear equally clean without magnification. The premium for VVS reflects natural rarity rather than a guaranteed visible improvement.

Some buyers appreciate the rarity and prestige of very high clarity. Others prefer to choose an eye-clean diamond and place more of their budget toward cut or carat weight. Neither approach is inherently wrong.

The best choice depends on what you value.

Can an Inclusion Help Identify a Natural Diamond?

Yes. A diamond’s inclusion pattern can help professionals identify the stone.

The clarity plot on a grading report maps significant characteristics and acts like a reference diagram. When combined with the diamond’s measurements, laser inscription, and report number, it can help confirm that the stone matches its documentation.

Because every natural diamond has an individual pattern, its inclusions can function much like a fingerprint. That feature can be useful during appraisals, repairs, inspections, and future trade-ins.

However, identification should still rely on professional examination and complete documentation rather than a single visible characteristic.

Should You Buy a Flawless Natural Diamond?

A Flawless natural diamond may be appealing if you value extreme rarity, collectability, or the knowledge that no clarity characteristics are visible at 10× magnification.

However, most engagement ring buyers do not need a Flawless grade to achieve a visually perfect appearance.

Consider a higher clarity grade when:

  • Rarity is a major priority

  • You are choosing a large natural diamond

  • You prefer an emerald or Asscher cut

  • You are purchasing an important collector-quality stone

  • You want a particularly prestigious combination of grades

Consider a carefully selected VS or SI natural diamond when:

  • You want an eye-clean appearance

  • Visible beauty matters more than microscopic purity

  • You want to maximize size or cut within your budget

  • The inclusion is small, unobtrusive, and structurally harmless

  • An expert has examined the diamond in person

A natural diamond does not need to be Flawless to be extraordinary.

Why You Should Compare Natural Diamonds in Person

Online images and grading reports provide useful information, but they cannot fully demonstrate how an inclusion behaves in ordinary viewing conditions.

A magnified 360-degree video may make a tiny inclusion appear dramatic even though it is invisible on the hand. Conversely, photography may fail to reveal widespread clouds or transparency issues.

When comparing natural diamonds in person, ask to see them:

  • Without magnification

  • Under a 10× loupe

  • In bright showroom lighting

  • In softer ambient lighting

  • Face-up and from the side

  • Against different metal colors

  • Beside stones with similar clarity grades

This process helps separate a harmless identifying characteristic from an inclusion that affects beauty or durability.

Why Mervis for a Natural Diamond?

Mervis Diamond Importers has helped generations of Washington, DC–area couples select natural diamonds based on more than grading reports.

Every Mervis diamond is hand-selected by Zed Mervis for cut, polish, symmetry, sparkle, and overall visual performance. The company evaluates the complete stone rather than accepting it simply because its grades look attractive on paper.

As a member of the Natural Diamond Council, Mervis is proud to educate clients about the rarity, origin, and individual character of natural diamonds.

At a Mervis showroom, you can:

  • Compare natural diamonds side by side

  • Examine inclusions under magnification

  • Determine whether a diamond is eye-clean

  • Understand the clarity plot and grading report

  • Evaluate beauty in different lighting

  • Ask whether an inclusion affects durability

  • Balance clarity with cut, color, and carat weight

  • Select an appropriate setting

  • Receive guidance from GIA-trained experts

  • Access professional cleaning, inspection, and future service

Mervis has showrooms in Washington, DC; Tysons, Virginia; and Rockville, Maryland, serving natural diamond buyers throughout the DMV area.

The Mervis Perspective: Character Matters More Than Perfection

Inclusions are not automatically defects. They are natural characteristics that must be understood in context.

A small inclusion may make a natural diamond more affordable without changing how beautiful it looks. Another may provide a recognizable fingerprint that makes the diamond individually identifiable. Certain inclusions can affect transparency or durability, but these should be identified through expert evaluation rather than fear of every microscopic feature.

The right question is not simply, “Does this natural diamond have inclusions?”

Almost every natural diamond does.

The better questions are:

  • Can I see them?

  • Do they affect the sparkle?

  • Do they create a durability concern?

  • Is the diamond beautiful?

  • Does its rarity justify the price?

  • Is this the right balance for me?

A natural diamond’s value lies not in artificial sameness but in its authentic origin, individual beauty, and geological story. Its inclusions may be part of that story—ancient signatures carried from deep within the Earth into a piece of jewelry that can become part of your own history.

Schedule an appointment with Mervis Diamond Importers to compare hand-selected natural diamonds and understand their unique characteristics.

Frequently Asked Questions About Natural Diamond Inclusions

Are inclusions normal in natural diamonds?

Yes. Most natural diamonds contain internal characteristics created during their formation deep within the Earth. Diamonds with no inclusions visible at 10× magnification are exceptionally rare.

Are diamond inclusions visible to the naked eye?

Many are not. Natural diamonds in the VS and carefully selected SI clarity ranges often appear eye-clean, meaning their inclusions cannot be readily seen without magnification.

Do inclusions mean a natural diamond is low quality?

No. The effect depends on the inclusion’s size, type, number, position, and visibility. A small inclusion may have no noticeable impact on beauty or durability.

Can natural diamond inclusions affect sparkle?

Minor inclusions generally do not affect sparkle. Large or widespread inclusions may reduce transparency or interfere with light performance. Cut quality remains the most important factor in brilliance.

Can an inclusion cause a diamond to break?

Most inclusions do not create durability problems. However, large surface-reaching feathers, cavities, or inclusions near vulnerable edges and corners should be professionally evaluated.

What is the best clarity grade for a natural diamond?

There is no single best grade. VVS and VS diamonds offer high clarity, while carefully selected SI diamonds can provide excellent value when they are eye-clean and structurally sound.

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