Types of Diamond Inclusions

Close-up of Diamonds

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Diamond inclusions are characteristics that occur inside the gemstone. They are usually called flaws because their presence means the diamond cannot be graded as internally flawless. 

Not many of us can afford internally flawless diamonds, so inclusions are to be expected to some degree. These small flaws are like fingerprints, a characteristic that gives us all an individual signature. Getting to know your diamond inside and out makes the stone a more personal possession—and will help you describe and identify the gem if it is ever lost or stolen.

What Is Diamond Grading?

Once they're certified by such institutions as the Gemological Institute of America, they're given a grade between zero and 10; zero being the best grade and 10 being the worst. The order of the grading system starts with cut then color, clarity, and lastly, carat weight. Lower quality diamonds will rank closer to zero than they will to 10.

Some inclusions are nearly impossible to see with the naked eye, whereas other inclusions affect a diamond's clarity. These flaws make the diamond less brilliant because they interfere with light as it passes through the stone. Even worse are the types of inclusions that can make a diamond more vulnerable to shattering.

Remember, there are few perfect diamonds, and the ones that are perfect are quite expensive, so the diamonds we buy all have varying amounts of internal and external flaws. Most jewelers tell us not to worry about diamond inclusions if they do not affect the stone's strength or severely impact its appearance. You can actually save a lot of money on a diamond if you opt to buy one with more inclusions. Here are the different types of diamond inclusions to consider.

Crystals and Mineral Inclusions

Diamonds can have tiny crystals and minerals embedded in them. A diamond can even be embedded with other diamonds. Many of these crystals cannot be seen without magnification, but a large chunk or grouping of crystals that detracts from a diamond's appearance lowers its clarity grade and its value.

There are times that a small crystal can add character to a diamond. A diamond with a tiny garnet inside would be a conversation piece—and an excellent personal choice for someone whose birthstone is garnet.

Pinpoint Inclusions

Pinpoints are extremely small light or dark crystals in diamonds that can either appear by themselves or in clusters. Larger clusters of minute pinpoints can create a hazy area in the diamond called a cloud which will affect the diamond's clarity rating.

Laser Lines

Laser lines are not a natural diamond inclusion. These vapor-like trails are left behind when lasers are used to remove dark crystal inclusions from the diamond. The machine-made trails look like tiny strands of thread that begin at the diamond's surface and stretch inward, stopping at the point where the inclusion was removed.


Feathers are cracks within the diamond that resemble feathers. Small feathers do not usually affect a diamond's durability unless they reach the surface on the top of the stone, a location that's prone to accidental blows.


Diamond cleavage is a straight crack with no feathering. A cleavage has the potential to split the diamond apart along its length if it is hit at the correct angle.

Small cracks that are not visible when a diamond is viewed in a table-up (face up) position do not seriously affect clarity ratings.

Girdle Fringes or Bearding

Girdle fringes, or bearding, are hair-like lines that can occur around the girdle during the cutting process. Minimal bearding is usually not a problem, but extensive fringing is often polished away or removed by re-cutting the diamond.

Grain Lines or Growth Lines

Grain lines are created by irregular crystallization that takes place when a diamond is formed. Colorless grain lines do not usually affect diamond clarity unless they are present in large masses. White or colored grain lines can lower a diamond's clarity grade.

Inclusions can be intimidating, so don't depend on just a clarity grade to know whether or not a diamond's inclusion is interfering with a diamond's beauty. This is especially true if you are shopping for clarity grades rated SI or less. Always shop for diamonds from a dealer you trust and find someone who can answer your questions about the diamonds you are considering.

If you want to see some of these diamond inclusions firsthand, ask your jeweler to show you each diamond under magnification and explain its characteristics to you.

Not only do inclusions impact a diamond's clarity, but so do surface blemishes. Read more about surface blemishes on diamonds for more information about flaws that can affect diamond clarity and strength.