People sometimes mistake diamond inclusions for “flaws.” But, instead, they tell a story about the formation of the diamond and mark each as unique creations. Like snowflakes, no two diamonds are identical, and inclusions are what make them distinct from one another.

Types of Diamond Inclusions to Avoid | Diamond Feather Inclusion | K. Rosengart

What Are Diamond Inclusions?

An inclusion is a small imperfection that is created from extreme heat and pressure. Of course, diamonds with large inclusions have lower clarity grades and can carry a lower value than those with small inclusions - but diamond inclusions are only one of several clarity grading factors.

Exceedingly few diamonds are “perfect” - or have no inclusions. The presence of inclusions does not negate the value of the stone if it possesses other qualities, such as clarity, cut, and carat weight. In fact, inclusions can be quite a benefit as they help you identify your diamond, authenticate it, verify that it is natural, and even tell trained gemologists where it came from. 

Diamond Inclusion Types

As mentioned, inclusions tell a story. Experts can study an inclusion and determine how the diamond formed, what minerals it was exposed to, what the growth environment was like, and more. There are different types of diamond inclusions, including:

  • Pinpoint. This is a very small mineral crystal (and it could even be a diamond crystal within the larger diamond). As small as a speck of dust, it does not impact the visual clarity of the diamond. It’s difficult to see even with magnification. A diamond may have a group of pinpoints, which can be so small that they “blur” together into a hazy form, called a “cloud.”
  • Crystal. This is mineral in crystal form that is embedded in the diamond. A dark crystal has a medium to dark tone.
  • Needle. This inclusion is a long, rod-shaped crystal embedded in the stone.
  • Knot. A knot is a crystal that extends to the diamond’s outermost surface area. What is interesting about these is that they can take on shapes such as hearts or bees or be red, green, grey, or black. Most often, though, they are shades of white or colorless.
  • Feather. A diamond feather inclusion has a wispy appearance, much like a feather (hence the name). With a diamond feather inclusion, clarity is a concern. It is advisable not to purchase stones with feather inclusions with a clarity grade lower than VS. Thus, this is one of the major types of diamond inclusions to avoid.
  • Grain Line. This is a colorless, subtle line caused by a disruption in the diamond’s growth process.
  • Twinning Wisp. Also the result of disruptions, twinning wisp diamond inclusions are a series of small pinpoints or clouds.
  • Chip. This little irregular opening is usually situated on the edge of the girdle.

Diamond inclusions tell us a great deal about the formation of the diamond and its journey to the surface of the earth. While inclusions can impact clarity - and thus structural integrity and value - the vast majority of stones have them. Work with your jeweler to understand if the inclusion will cause any issues or is simply an interesting part of your diamond’s identity and story.

At K. Rosengart, our diamond cutting, sorting, and analyzing services ensure you receive properly graded diamonds with a relative lack of inclusions and blemishes.


Diamond Education Guide for Consumers | FREE PDF Download | K. Rosengart