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Diamond Inclusions
Inclusions exist in virtually all diamonds, whether natural or lab grown. These internal features affect a diamond's clarity grading, value, and appearance.
Diamond Imperfections Explained
Diamond inclusions are internal characteristics that form during crystal growth. In natural diamonds, these develop over millions of years underground. In lab diamonds, they form during the growth process. These tiny imperfections can be crystals of other minerals, small cracks, or areas where the diamond's crystal structure grew in a slightly different way. While the word "inclusion" might sound negative, it's simply the technical term gemologists use to describe these internal characteristics.
There's an important difference between inclusions and blemishes that's worth understanding:
- Inclusions are internal features that formed inside the diamond during its creation
- Blemishes are external marks that happened after the diamond formed, usually during cutting or wear
Both inclusions and blemishes affect a diamond's clarity grade, but they impact the stone in different ways.
Diamond Inclusion Scale
The diamond inclusion scale, developed by the Gemological Institute of America (GIA), provides a standardized way to grade diamond clarity. This scale runs from Flawless (no inclusions or blemishes visible under 10x magnification) to Included (inclusions visible to the naked eye).
Types of Diamond Inclusions
Diamond imperfections fall into two primary categories: internal inclusions (features trapped inside the diamond) and external blemishes (surface imperfections). Understanding these distinctions, along with the different inclusion patterns in natural and lab grown diamonds, provides critical context for evaluating a diamond's quality, appearance, and value.
Internal Inclusions
Internal inclusions occur during a diamond's formation process, when foreign materials become trapped within the crystal structure or when disruptions affect the diamond's growth pattern. These features exist within the diamond itself and cannot be removed without cutting away portions of the gem.
- Cavity: An angular opening that occurs as a feather breaks further.
- Cloud: A cluster of pinpoints that give a hazy appearance.
- Crystal: A mineral crystal within a diamond.
- Feather: A small breakage or crack that might appear white and feathery.
- Graining: Lines, angles, and curves that appear whitish, colored, or reflective.
- Needle: A thin, elongated crystal that looks like a rod at 10x.
- Knot: A white or transparent crystal that extends toward the diamond's surface.
- Pinpoint: A small crystal that looks like a tiny dot at 10x magnification
External Blemishes
Unlike inclusions, blemishes are confined to the diamond's surface and don't penetrate the interior structure. While generally less concerning than internal flaws, prominent blemishes can affect appearance and sometimes durability.
- Abrasion: A series of nicks that give the edges a white, fuzzy appearance.
- Chip: A shallow opening on a stone's surface that most often occurs at the girdle or culet.
- Natural: A portion of the rough diamond's original surface or skin that remains on a fashioned gem.
- Nick: A small notch on a facet junction, usually along the girdle edge or at the culet.
- Pit: A small opening that appears as a tiny white dot.
- Rough girdle: A granular girdle surface.
- Scratch: A thin white line along the diamond's surface.
Natural Diamond Inclusions
Inclusions in natural diamonds act as authenticity markers that help gemologists reliably distinguish natural diamonds from lab grown ones. Natural diamonds typically display distinctive growth lines or graining patterns that record changes in pressure, temperature, and carbon availability during their formation over millions of years. These characteristic internal features create unique zoning patterns that laboratory processes cannot replicate.
Lab Diamond Inclusions
Lab diamonds can have inclusions despite being created in controlled environments. These inclusions differ from natural diamond inclusions. While both lab and natural diamonds share identical chemical composition, lab diamonds develop distinctive inclusion patterns. These distinctive patterns often stem from variations during their accelerated formation process, such as inconsistencies in temperature, pressure, or foreign particles in the growth chamber. This difference between lab and natural inclusion patterns extends to terminology in grading reports. What gemologists call a "pinpoint" or "feather" in natural diamonds might be labeled a "growth remnant" in lab diamond documentation.
Visible Inclusions in Diamonds to Avoid
When evaluating diamonds, certain inclusions require special caution due to their potential impact on both durability and appearance. Surface-reaching inclusions like large feathers, deep cavities, and exposed crystal knots pose the greatest concern, especially when located near vulnerable points of fancy-cut diamonds. These structural imperfections can compromise the stone's integrity and may worsen with normal wear.
Inclusions that affect clarity and brilliance also warrant careful scrutiny. Large clouds creating a hazy appearance and prominent dark crystals visible to the naked eye can significantly diminish a diamond's beauty and value.
Here are specific inclusion types to be particularly cautious about:
- Large feathers at vulnerable points: These inclusions create significant risks when located near points or thin edges, especially in fancy cuts like princess or marquise shapes. A feather extending from girdle to surface can create a weakness that may lead to chipping.
- Deep cavities or significant knots: These surface-breaking inclusions create vulnerable points in the diamond's structure. Over time, they can trap dirt, expand with wear, and potentially compromise durability.
- Large or dense clouds: While common, extensive cloud formations can create a hazy, "sleepy" appearance that diminishes brilliance.
- Dark or prominent crystals: Most concerning when centrally located under the table facet or when visible to the naked eye. Dark crystals create noticeable contrast that impacts appearance and value.
Diamond Inclusion FAQ
What do diamond inclusions look like?
Diamond inclusions appear in various forms, each with distinctive visual characteristics. Pinpoints — the most common type — look like tiny white or black dots, often requiring magnification to see clearly. Feathers resemble delicate, transparent fracture lines that can catch light in certain angles. Clouds create hazy areas composed of numerous clustered pinpoints that can give portions of the diamond a slightly foggy appearance.
Do lab grown diamonds have imperfections?
Lab grown diamonds can have impurities, particularly in the form of trace elements or foreign particles introduced during their growth. For instance, metallic inclusions are common in HPHT diamonds, while uncrystallized carbon may appear in CVD diamonds. These impurities do not diminish the diamond's overall durability but may affect its clarity grade.
Are inclusions bad in a diamond?
Inclusions aren't inherently "bad"—they're characteristics that tell the diamond's formation story. Their impact depends entirely on visibility, location, and type. Most inclusions in VS2 and higher clarity grades remain invisible to the naked eye and don't affect a diamond's beauty or structural integrity.
The practical approach is evaluating whether inclusions impact:
- Appearance: Do they diminish the diamond's brilliance or create visible dark spots?
- Durability: Do they compromise structural integrity (particularly feathers near edges)?
- Value: Do they significantly affect the diamond's market value relative to similar stones?
What are the best inclusions to have in a diamond?
The most favorable inclusions are those with minimal visual and structural impact:
- Pinpoints: Tiny white dots typically invisible without magnification
- Small transparent crystals: Colorless mineral inclusions that don't interrupt light flow
- Wisps or faint graining: Subtle growth lines that don't create visible clouding
- Inclusions positioned under facets: Features hidden beneath the crown facets rather than under the table
- Twinning wisps: Growth features often found in higher clarity stones
Why do lab grown diamonds have inclusions?
The inclusions in lab grown diamonds are an organic byproduct of their growth process. Depending on the method of creation, the reasons for these inclusions can vary:
HPHT Method:
- This method mimics the high-pressure, high-temperature conditions under which natural diamonds form.
- Metallic inclusions, such as iron, nickel, or cobalt, may result from the metal catalysts used during the growth process.
- Irregularities in temperature or pressure can also lead to inclusions like tiny voids or irregular growth patterns.
CVD Method:
- Inclusions in lab diamonds grown through CVD primarily result from impurities in the carbon source or uneven growth on the diamond seed plate.
- Inclusions include black pinpoints, which are tiny spots of uncrystallized carbon, and graining patterns caused by uneven growth.
Understanding these inclusions helps gemologists assess the quality and authenticity of lab grown diamonds while providing insights into their formation. To learn more, read our guide on How Lab Diamonds Are Made.
What inclusions might be found in a lab grown diamond?
Lab grown diamonds can exhibit a variety of inclusions, many of which differ from those in natural diamonds:
- Metallic Inclusions: Found mainly in HPHT diamonds, these are small traces of the metal catalysts used in the process. Depending on the lab diamond’s clarity grade, these inclusions are often visible under magnification.
- Graining Patterns: Sometimes present in CVD diamonds, these appear as striations within the diamond, and are caused by uneven growth during its formation.
- Pinpoints: These appear as tiny black or white spots resulting from uncrystallized carbon or other impurities.
- Clouds: Groups of microscopic inclusions that can create a hazy or cloudy effect in the diamond.
- Graphite Inclusions: These are the result of remnants of the carbon source used in their creation.
Lab grown diamonds are thoroughly inspected for these inclusions, ensuring their clarity grade reflects their overall visual attributes.
How do inclusions affect diamond price?
Inclusions impact diamond value through their influence on clarity grade — one of the 4Cs (cut, color, clarity, carat) that determine pricing. Generally, as clarity improves, value increases exponentially, with prices jumping significantly between major clarity thresholds.
The value impact varies depending on:
- Clarity grade jump: A difference between VS1 and VVS2 typically affects price less than between SI2 and SI1, where the threshold of eye-visibility often occurs
- Diamond size: Inclusions have greater price impact in larger stones where they're more easily visible
- Diamond shape: Emerald and Asscher cuts with their large, open facets show inclusions more readily than brilliant cuts, affecting value accordingly
Can inclusions get worse over time?
Most inclusions remain stable indefinitely, but certain types can potentially worsen under specific circumstances:
- Feather inclusions that reach the surface may expand if the diamond experiences significant impact or extreme temperature changes
- Inclusions near thin girdles or points in fancy-shaped diamonds face higher risk of expanding if struck
- Strain-related inclusions might respond to force differently than surrounding material
Can inclusions be removed?
Most inclusions cannot be removed without fundamentally altering the diamond. However, certain approaches can address specific inclusion types:
- Laser drilling: For dark crystal inclusions, specialized lasers can create microscopic tunnels to reach the inclusion, which is then dissolved with acid. The resulting tunnel remains as a permanent feature.
- Fracture filling: For surface-reaching feathers, glass-like material can be injected to improve the diamond's appearance. This treatment requires disclosure and may need future retreatment.
- Re-cutting: Removing portions of the diamond through cutting and repolishing can eliminate surface-reaching inclusions at the cost of carat weight.
