Here’s a comprehensive list of common inclusion types found in a diamond. With the use of images and videos (photography credits – James Allen), I hope you get a better idea of how to identify them and understand the visual impact an inclusion may have on a finished diamond.
Bearding – Hair-like inclusions that form at the girdle area due to improper bruting processes. A heavily bearded girdle with a grey fuzzy appearance should be avoided.
Graining – Caused by irregular crystal growth. Internal graining can appear like whitish, colored or reflective lines. Depending on the severity, they can also appear like creases or give the diamond a hazy appearance.
Image credits: Vincent Cracco, © GIA
Cavity – This usually takes the form of a large or deep opening in the diamond’s surface. Cavities are usually created during the polishing process when an internal inclusion like a crystal falls out of its pocket. Read this article for more insights.
Crystals – Included minerals that exist within the body of the diamond. Depending on the type of minerals they are, they can be colorless (another diamond embedded with), black (carbon), reddish (garnets), greenish (peridots) and etc… Since colored crystal inclusions are much more obvious to the naked eye, they are generally undesirable.
Crystals can exist in different kinds of shapes and colors.
Cloud – A cloud inclusion is a very broad term used to classify a cluster of pinpoints/crystals found very close to each other. Depending on the nature of the cloud inclusion, it can sometimes pose an issue to the diamond’s appearance.
For example, when clouds get too big in size and density, they can cause the diamond to take up a hazy appearance and negatively affect its light transmission properties. If they are small and diffused, it generally isn’t a cause for concern.
This dense and visible white cloud sets the clarity grade in this SI1 emerald cut.
Varying intensities and coloration of cloud inclusions.
Feather – A small crack or fracture within the diamond. Depending on your viewing angle, a feather can look transparent and almost invisible or it can catch on light and display a whitish appearance.
Severe feathers can cause durability issues (especially if they are surface reaching or near the girdle area) or have unsightly coloration to them; both of which should be avoided.
On left: Due to the size and location of the feather, there is additional risks of chipping the diamond.
On right: A brownish coloration causes the feather to be very obvious to the naked eye.
Needle – A long thin needle-shaped (tiny-rod) inclusion that is usually white or transparent in color. If they appear in clusters, it might affect cause a detrimental effect on the diamond’s clarity.
Super obvious needle that runs across the middle of the stone.
Small, transparent and elongated needle under the pear’s table facet.
Pinpoints – These are very small white or black crystals that are embedded inside a diamond.
Can You See Faint White Pinpoint?
Twinning Wisps – This inclusion is a result of growth defects in a diamond’s crystal structure. During a diamond’s formation process, it may stop growing due to unfavorable conditions and twinning wisps are form when growth restarts (say for example thousands of years later) in a different direction.
In essence, twinning wisps are a mish-mash of different inclusions such as pinpoints, crystals, feathers and clouds that resembles a somewhat twirly plane.
Faint twinning wisp that can hardly be made out to the unaided eyes.
This video shows a heavily twinned heart cut with an I1 clarity.
Chip – A small opening on the surface of a diamond often found near the edges or facet junctions. This inclusion is typically man-made in the sense that it is damage caused by wear and tear or accidental knocks.
Indented Natural – A “flaw” which dips below the polished diamond’s surface. An indented natural is a part of the rough diamond that was left untouched during the polishing process and is usually found at the girdle.
Indented natural indicated by red arrows. Source: GIA
So far, what I had shown you is a list of common inclusions found in a diamond. However, there are several clarity characteristics like etched channels or manufacturing remnants that are uncommonly seen and I have included the links here for the sake of completeness.
Moving on, did you know many shoppers actually make critical mistakes by selecting diamonds based solely on information from a grading report? The fact is, there are many hidden clarity related details that lab reports NEVER reveal to you. On the next page, I’ll show you why and how you can overcome the pitfalls of buying blind…