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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 contain inclusions that differ from natural stones. While both share identical chemical composition, lab diamonds develop distinctive inclusion patterns due to their controlled, accelerated growth process.
This difference 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.
