Diamond Inclusion Types in a clarity plot and which to avoid

Diamond inclusions are among the major factors influencing the appearance of a diamond! Nobody wants to have a diamond with visible inclusions. And nobody would like to have a diamond with inclusions that pose a durability risk!

In my post about diamond clarity I have referred to diamond clarity in general. In this post we will go deeper into each single inclusion type that you might stumble upon in your grading report!

So, what diamond inclusion types do exist and which pose a serious concern?

Complete list of diamond inclusion types in GIA a plotting diagram

I have compiled a comprehensive list of the most common diamond inclusion types and clarity characteristics with examples and explanations.

General rules for reading a diamond clarity plot

What you have to bear in mind when reading a clarity plot is the fact that the first inclusion on the grading plot is the grade-setting inclusion. The grade-setting inclusion is the one that is mainly responsible for the clarity grade.

Furthermore, internal flaws are indicated in red color and external flaws are marked as green color.

GIA and AGS usually only issue clarity plots for diamonds above one carat. So don’t be surprised if a diamond under one carat does not have a clarity plot in its grading report.

Looking at a diamond clarity plot is a great way to obtain more accurate information about a diamond’s inclusions. However, it is never enough to only look at the grading report or clarity plot of a diamond. This is why you should never buy a diamond blinly. Just have a look at the two clarity plots below:

Clarity plot of a diamond with crystal inclusions  Another clarity plot of a diamond with crystal inclusions

Both diamonds  are SI2 diamonds that have Crystal inclusions under the table. As far as the the crystal inclusions under the table are concerned they look pretty similar. But let’s have a look what both diamonds really look like:

 SI2 diamond with a large black crystal inclusion  SI2 diamond with a large white crystal inclusion

As you can see the Diamond on the left has a pretty ugly and easily visible stark black Crystal inclusion. The diamond on the right only has a white crystal inclusion however which would be much more difficult to detect in the real diamond. Admittedly in this case both diamonds would not be eye clean but the right choice would still be a much better choice than the left diamond.

Furthermore, if you look at the clarity plot and the actual diamond of the left example you will come to realize that it is only the one black crystal inclusion under the table that will be visible to the naked eye. This even though there are so many other tiny crystals and clouds in the diamond.

Go and checkout James Allen as this is the only online vendor that will let you view all of its diamonds in high definition 360° videos in up to 40x magnification!

Let’s go for it and have a close look at the most common diamond inclusion types that you can find on a grading plot.

Laser drill hole as a diamond clarity characteristic

Why would there be a laser drill hole in a diamond? Who would do something like that and why?

The reason is quite simple. Laser drilling is a great method  to enhance the clarity of a diamond artificially. Usually a laser will drill a microscopic tunnel into a diamond to remove an internal black inclusion.

A “laser drill hole” will be indicated on a clarity plot by a red point surrounded by a green circle:

Laser Drill hole diamond inclusion type on a clarity plot

If however the drilling hole in the surface can not be made out easily instead of the “Laser Drill Hole” mark you will find a comment in the comments section saying “Internal laser drilling is present”.

There is a great misunderstanding as to GIA not grading artificially enhanced diamonds. Because in fact GIA does grade laser drilled diamonds and this is why the “Laser Drill Hole” sign exists.

Now, GIA does not grade clarity-enhanced diamonds with enhancements that are not permanent in its nature. An example for that would be fillings of laser drilled holes that could be removed again. A laser drilled hole as such is permanent in its nature however and will thus be graded by GIA.

Any laser drilling of the diamond must be disclosed by the seller as a laser drilling severely affects the price of the diamond.

Enlarged you can imagine a laser drill hole to look something like this:

Laser Drill Hole in a diamond


The picture above is highly enlarged and most laser drill tunels are not visible by the naked eye.

Whether you want to buy a diamond with a laser drill hole is up to you. At any rate, a diamond with a laser drill hole should be a little cheaper because of the artificial visual enhancement.

The diamond crystal inclusion

A crystal inclusion refers to mineral deposits and other diamonds that are trapped within a larger diamond. Crystals are among the very common inclusions and they have the appearance of bubbles.

The crystal inclusion is shown as a simple red circle in a diamond clarity plot:

Crystal diamond inclusion type on a clarity plot

A crystal can come in various shapes and colors which is dependent on the specific mineral that is trapped within the diamond.

A diamond that is trapped within a diamond forms a white crystal inclusion:

SI2 diamond with a large white crystal inclusion SI2 diamond with white crystal inclusion

Black crystal inclusions usually consist of carbon or graphite:

SI1 damond with black crystal inclusion under the crown facets SI2 diamond with a large black crystal inclusion

Reddish crystal inclusions are usually garnets:

Included garnet crystals in a diamond

Rarely you can also see greenish inclusions in a diamond which are Peridots.

The main rule  for crystal inclusions is to only choose white crystal inclusions. If they are not too big there are good chances that the crystal will not be visible to the naked eye.

Furthermore, white crystal inclusions under the crown facets are more difficult to detect than say a white crystal inclusion directly under the middle of the table. Obviously, this pertains to crystal inclusions in SI1 or SI2 diamonds. In VS2 diamonds and above graded by GIA and AGS you will not have to worry about any visibility issues.

Dark crystals however can usually be perceived by the naked eye. Particularly if it is the grade-setting inclusion in a SI1 or SI2 diamond. You should definitely avoid such diamonds.

Crystal inclusions in an eye clean diamond are usually too small to pose a serious durability risk to the diamond. Typically, inclusions that do pose a durability issue cover a larger area of the diamond and thus create a cleavage plane within the stone. Larger feathers near the girdle area or cavities would be good examples for inclusions that could potentially pose a durability risk.

If you have any question about a particular inclusion in a diamond I will be more than happy to help you out. Just leave me a comment or write me a mail!


Needle inclusion as a diamond clarity characteristic







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