Internal Diamond Clarity

Inclusions - A Diamond's Internal Clarity Characteristics

This is a detailed technical page. Please see our diamond clarity page if you need a more general overview. Also you can see our Guide to Buying Engagement Rings if you want to know about our diamond quality policy.

Your diamond's individual characteristics determine its clarity grade. These features can be marked on your diamond certificate. The characteristics may be on the diamond's external surfaces or internal, in the diamond crystal itself.

Diamond Clarity

The term 'inclusions' describes any clarity imperfections that penetrate into or are wholly embedded within a diamond. Inclusions occur naturally and provide evidence that the gemstone is a natural diamond. There are a number of different internal clarity characteristics with a variety of impacts on the performance of a diamond. The key terms are as follows - it may be interesting for you to read on and find out what they mean:


Fine hairline fractures travelling into the stone from the girdle.

Carbon Spots

These are included in crystals that have a dark appearance rather than a white or transparent appearance under a microscope.


A hazy area in a diamond, usually made up of a grouping of tiny pinpoints. Too small to be distinguishable from one another, even under magnification, the result is that under a microscope they often look like a soft transparent cloud within the diamond. Clouds can scatter light and diminish transparency, but in most cases this sort of inclusion does not significantly affect a diamond's clarity grade.


A mineral crystal formation contained within a diamond, usually colourless. However, sometimes coloured crystals or other minute gemstone crystals, such as a garnet crystal, form inside the diamond. (See also 'pinpoint' below)


These are small, usually natural, cleavages running along the internal grain of a diamond. In some cases the feather both begins and ends within the diamond's surface - in other cases, the feather begins inside the diamond and extends out to the surface. When viewed under magnification, some feathers are transparent and others have a light, white appearance to them.


Similar to feathers except that they do not follow the grain and are usually irregular or curved.


Also known as 'feathers', as above.

Internal Graining

This is a visible structural phenomenon caused by differences in crystal orientation or irregularities in the crystal structure. Internal graining can have a considerable affect on a diamond's grading.

Laser-Drill Holes

A fine tube-like hole made by a laser, which will appear as a frosted or colourless needle in the stone when viewed through the pavilion. Laser drilling is a man-made attempt to raise a diamond's clarity by creating a space in which to inject acid to dissolve dark internal crystals.


Occurring singly or in groups, pinpoints are extremely small included crystals.

Twinning Wisp

A cloudy area usually found in association with a twin plane. Caused by crystal distorton, it will appear as a flat cloud and is often characterised by trails that wander on one plane.

You can learn more from our diamond clarity page, or read about external clarity characteristics and clarity grading.

Let's Go Shopping for an Engagement Ring

Diamond Engagement Rings Hopefully we've covered all the important things you need to know about engagement rings. If you still have any questions, there's plenty of information in the rest of our Guide to Buying Engagement Rings, or you can always contact us and we'll be happy to help.

If you are ready, let's go shopping.

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