What Are Inclusions In Diamonds?

When you hear about a diamond’s clarity, what you’re really hearing about are its inclusions and surface features. Inclusions are the internal characteristics that form naturally within a diamond during its growth process, whether deep underground over billions of years or inside a laboratory during controlled growth.

They are not flaws to be ashamed of—they are a normal part of nearly every diamond. What matters is understanding them, because inclusions directly influence clarity grade, value, and sometimes durability.

The Definition of Diamond Inclusions

Inclusions are internal features within a diamond’s crystal structure. They can be other minerals, breaks in the lattice, or growth patterns that occurred during formation.

Gemologists study inclusions under 10x magnification to determine a diamond’s clarity grade. The GIA (Gemological Institute of America) defines inclusions as internal characteristics, while external features are referred to as blemishes.

How Do Inclusions Form?

• In natural-mined diamonds: Inclusions form over billions of years as carbon crystallizes under extreme heat and pressure. Small amounts of other minerals, or irregularities in crystal growth, become locked inside.

• In lab-grown diamonds (HPHT or CVD): Inclusions can occur during the growth process. HPHT diamonds sometimes show metallic inclusions, while CVD diamonds may exhibit strain patterns or internal graining.

Both are genuine diamonds, and both are evaluated with the same clarity standards.

Types of Diamond Inclusions

Not all inclusions are the same. Some are harmless and microscopic, while others may affect appearance or durability.

1. Feathers: Small fractures inside the crystal, which may look like wisps or cracks. Large feathers near the girdle can make the stone more vulnerable to chipping.

2. Pinpoints: Very tiny crystals trapped inside, often white or black.

3. Clouds: Clusters of pinpoints that create a hazy or milky area.

4. Crystals or Mineral Inclusions: Small foreign crystals that appear as dark, transparent, or colored specks.

5. Needles: Long, slender crystals inside the diamond.

6. Internal Graining: Irregular growth lines that may appear as faint lines, angles, or curves inside the stone.

Professional insight: The location, size, and type of inclusion matter more than the mere presence.

How Inclusions Affect Diamond Clarity

Clarity is one of the 4Cs of diamonds (cut, color, clarity, carat). It refers to how free the diamond is from inclusions and blemishes.

The fewer and smaller the inclusions, the higher the clarity grade. The GIA clarity scale is:

Can You See Inclusions Without Magnification?

• In FL, IF, VVS, and VS grades, inclusions are invisible to the naked eye.

• In SI grades, some inclusions may be visible, but many stones are “eye-clean.”

• In I grades, inclusions are visible without magnification and may affect transparency and sparkle.

Do Inclusions Lower Value?

Yes, inclusions directly influence price. Diamonds with fewer or less visible inclusions are rarer and therefore more valuable.

However, clarity is only one factor of value. Cut quality has a greater impact on brilliance, meaning a well-cut SI diamond may look far more impressive than a poorly cut VS diamond.

Do Inclusions Weaken Diamonds?

Most inclusions do not reduce durability. But inclusions like large feathers, cavities, or surface-reaching crystals can weaken the stone and increase the risk of chipping.

This is why buying from trusted jewelers like The Diamond Guys matters—we help you choose stones where inclusions do not compromise long-term wear.

Natural vs. Lab-Grown Inclusions

• Natural-mined diamonds: Inclusions are created by nature, such as crystals, feathers, and mineral traces.

• Lab-grown diamonds: Inclusions result from growth conditions. HPHT diamonds may contain metallic inclusions, while CVD diamonds often show growth striations.

Both types are graded using the same clarity scale.

Conclusion: Inclusions Define a Diamond’s Identity

Inclusions are not flaws—they are natural features inside every diamond. They help gemologists grade clarity, determine value, and distinguish one stone from another.

By understanding inclusions, you’ll make informed decisions when choosing your diamond—whether it’s a natural-mined diamond, a lab-grown option, or a custom engagement ring.

Explore clarity grades and inclusions in person at The Diamond Guys showrooms in Scottsdale and Los Angeles. Our experts provide honest, clear guidance so you can choose with confidence.

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