Last Updated on 24th March 2025

Feather inclusions in a diamond are among the most common inclusions to be found.

In some cases feathers can neither be seen by the naked eye nor do they pose a risk to the durability of the diamond. In other cases however, a feather can not only be a serious appearance concern but it could also potentially pose a durability risk.

(Pictures are courtesy of James Allen)

That is reason enough to have a close look at diamond feather inclusions.

Let’s do it in an orderly manner.

What are diamond feather inclusions?

The term “feather” in a grading report is a general term that refers to cracks, fractures or breaks in a diamond. It does not mean however that there is a real feather hidden in the diamond. That’s  in fact what most newbies think. Although sometimes there can also be a real feather included in the diamond but it is rather rare.

The term feather was coined because feather inclusions have a white and somewhat feathery appearance to them. In a grading report on a grading plot they are usually indicated as a red feather. Both GIA and AGS use the same signs in their plotting diagrams for a feather:

As you can see the plotting diagram is divided in two parts. For one thing in the upper half of the diamond and the lower half of the diamond. Both areas are divided through the girdle.

Sometimes it even happens that a feather located in the upper half of of the diamond breaks through the girdle area into the lower half of the diamond. In such a case it would look something like this:

(Picture is courtesy of AGS)

In such a case the same inclusion type has to be located at the exact same spot when you turn the diamond around.

Now, that you know the basics about feathers let’s have a look at the really relevant questions like eye cleanliness and diamond durability.

In which clarity grades are feathers visible to the naked eye?

In my post about diamond clarity I have described the main rule for getting the biggest bang for your buck: Choose a clarity grade beween VS2 and SI2.

Now, a VS2 clarity diamond graded by GIA and AGS will virtually always be eye clean. There are only very rare cases in which a VS2 diamond will not be eye clean. Thus, it is even wiser to choose an eye clean diamond with the SI1 or SI2 clarity range to get an even bigger bang for your buck. You should stay away from I1 though because I have never seen one that is eye clean.

Luckily, feather inclusions are the most difficult to make out with your naked eye because of their white appearance and often slim form.

The diamond below for instance is a SI1 diamond that is not eye clean. There are some feathers and twinning wisps included in the diamond as you can see from the plotting diagram.

The feathers temselves are not visible to the naked eye but the twinnings wisps are (still very difficult to make out for the naked eye). Twinning wisps are a series of pinpoints, clouds or crystals that formed in a diamond’s growth phase. A twinning wisp is therefore different in nature than a feather which is a mere break in the diamond.

As a conclusion it does have to be said that feathers rarely pose an appearance issue within a diamond. More often it is crystals, twinning wisps and crystals that impact the diamond’s appearance in an unfavourable way.

Fair enough, most people do not necessarily differentiate between different inclusion types because to them an inclusion is just an inclusion. Due to the slim and whitish nature of most feather inclusions they are clearly not among the chief factors in deteriorating a diamond’s look.

By the way, the best place to identify visible feather inclusions within a diamond is James Allen. No other diamond vendor will let you view ALL of their diamonds in high definition 360° videos in up to 40x definition!

Go and check out James Allen’s amazing diamond display technology now! You will even be able to inspect the diamond more closely than in a brick and mortar store!

In which cases do feathers pose a durability risk?

Alright, but what about durability issues then?

Feather inclusions are often discussed as durability issues, especially when the feather is situated directly near the girdle area or reaches the surface of the stone.

I have already discussed the feather durability issue for VS2 diamonds in another post. To put it short: In VS2 diamonds feathers are not a real durability issue because they are way too small.

If you have a look at the VS2 diamond below from Whiteflash’s A CUT ABOVE signature line you will see see lots of tiny feather inclusions both in the upper diamond and lower diamond half:

As you can see most of these feathers are reaching the surface. However none of these inclusions are breaking through the surface otherwise they would be shown as a cavity on the grading report.

Furthermore, none of these feathers is reaching through the girdle from the upper half to the lower half. If you rotate the diamond as indicated in the AGS demonstration above you will find that no inclusion from the upper half is directly opposite on the lower half.

Now, a larger inclusion reaching the surface and being located both in the upper and lower half of the diamond could potentially form a cleavage plane within the diamond. This could potentially weaken the diamond. A VS2 feather inclusion however is not big enough to exert such an effect.

You have to be aware that the diamond itself is going through a very rough polishing process in which the diamond even turns red because it gets heated up so much. Therefore smaller inclusions like VS2 feather inclusions will never really pose a serious durability risk.

Basically, diamond chipping mostly occurrs with I1 diamonds or worse. Although diamond chipping in and of itself is already a very rare event. It even hardly ever happens with SI1 or SI2 diamonds.

What might be more risky in SI1 and SI2 diamonds are crystal inclusions or cavities directly at the girdle area. Feathers would only slightly heighten the risk of diamond chipping if they are really big, reaching the surface and moreover being located both at the upper and lower diamond half (reaching through the girdle).

If you need any help with a particular inclusion and are unsure whether there might be a durability issue involved don’t hesitate to contact me. I will be more than happy to help you out! Just drop me a comment or write me a mail!