SI1 Diamonds – Do They Offer Better Value For Money?

Believe it or not, the bulk of diamonds in the market actually fall within the slightly included and included ranges. As the name itself suggests, slightly included (SI) diamonds have small imperfections and microscopic flaws in them.

Although the inclusions could be seen with ease using a 10X magnification loupe, SI1 diamonds will usually appear flawless to the naked eye of a casual observer. In fact, SI1 graded diamonds are great for people on a budget as they don’t have to compromise on cut quality to get a larger stone.

You could put a VS1 or VVS1 diamond beside an SI1 diamond and probably not tell the difference between the stones unless you examine them with a loupe.

In the SI clarity grade, you would usually expect to see inclusion types like clouds, carbon spots, pin points, twinning wisps or feathers (to name a few). What you really need to know is that even if two diamonds share the same exact GIA grading of SI1, they can look vastly different in real life.

collage of different si1 diamondsClick to view enlarged image…

Some diamonds may look totally eye clean and yet, some others might have flaws that would be noticeable immediately. Ultimately, the location, size and color of the inclusions play an important role in the face up appearance.

When buying diamonds in the SI clarity ranges, it is extremely important that you stay away from diamonds with eye-visible inclusions. To help you determine this, I’ve created a handy technique that you can easily use to weed out diamonds that aren’t eyeclean.

Examples of Diamonds You Should Look For…

Inclusions that are well distributed in the diamond.

– 0.72 Carat J SI1 Round Cut
– 1.01 Carat I SI1 Cushion Cut

eye clean si1 diamonds

I’m going to be totally honest with you here. The lower price tags on these two options do come with a certain trade-off. While these are great choices for eye-clean diamonds, both these stones have feathers found on the girdle edges.

The presence of the feathers at these locations makes them more susceptible to damage if an external force is applied in the right direction.

Inclusions That Can Be Hidden By Prongs (Prongable)

1.00 Carat K Color SI1 Excellent Cut Round Diamond

grade making feather inclusion

This is the kind of slightly included diamonds I would recommend. The feather is embedded within the body and also localized at a certain area. While the feather is colored and might be visible to the naked eye, it can be totally covered up by a prong during the setting process.

What Do You Need to Avoid And Take Note Of?

Big inclusions under the table facet of the diamond.

1.02 Carat D Colored Ideal Cut Round Diamond

big black crystal in middle of diamond

The size and location of the crystal inclusion makes this diamond a poor choice. Besides being visually obvious, the crystal is also reflected into multiple images around the crown facets. By viewing the magnified photograph carefully, you should be able to pick out the faint reflections at the 3 o’clock and 5 o’clock arrow heads.

Now, if you were to take a look at its accompanying grading report, that is the only inclusion noted in the plot. If it weren’t for this tiny crystal, the diamond would probably achieve an Internally Flawless (IF) grading instead.

I strongly encourage that you view and examine diamonds to get a good idea of how an SI1 diamond would look like prior to shopping. James Allen is a great place for you to do your research with their intuitive videos.

What About Any Additional Comments Found In The Reports?

Here are some other things you need to pay attention to. Very often, you will see comments in the GIA/AGS report stating “additional clouds are not shown” or “additional twinning wisps not show”.

Sometimes, these statements are non-critical issues and won’t impact the appearance of the diamond. At other times, they can cause diamonds to look hazy! Without physically seeing the diamond, you can’t really gauge whether this would be an issue.

1.54 Carat G SI1 Diamond – Emerald Cut

si1 g diamond - additional twinning wisps, surface graining not shown comment

Don’t rejoice too early if you think you found yourself a fantastic stone. The comments in this G SI1 diamond’s grading report is cause for concern. In such cases, it is best to have a gemologist inspect such diamonds or check the stone yourself.

1.00 Carat F SI1 Diamond – Round Cut

si1 f diamond

In this example above, the additional twinning wisps have caused the diamond to become cloudy in its appearance. If you click on the image, it’s pretty easy to see this from the video listing. Obviously, this is a diamond you definitely want to avoid.

Clean Looking Plots Are BAD And Signify Problems

If you see a grading report of an SI1 diamond similar to what is shown below, it is an immediate RED FLAG.

suspicious looking plots

All 3 plots are suspicious looking by typical SI1 clarity standards. Avoid!

Where are all the inclusions? Why does the clarity plot looks like it is depicting a VS1 or VVS2 diamond instead? Instead, you will see statements like “Clarity grade is based on xxxxxxxx that is not shown” or “xxxxxxxxx not shown” in the comment section of the report.

Chances are, the diamond is going to look hazy or cloudy due to numerous un-plotted inclusions. You can see one such example in the video below where the diamond’s brilliance is adversely impacted.


How to Shop For SI1 Clarity Diamonds The Right Way

The trick to buying great looking SI1 diamonds is to seek out those with inclusions that are well-spread out. If I am personally shopping for myself, I tend to look out for inclusions that blend well into the diamond’s body and I would stay away from inclusions found near the center of the diamond.

Keep in mind that you should NEVER buy a diamond in the slightly included ranges without eyeballing it. If an online vendor doesn’t offer you photographs or videos to inspect the stone, work with one who does. The rule is simple: No photographs/videos, no talk. You don’t want to end up with an appalling looking diamond to remind you of the bad decisions you made.

If you are specifically shopping for an SI1 clarity diamond, James Allen is the best place to start your search. Not only do they provide magnified photographs and videos, they also have a huge selection for consumers with different budget ranges.

To put your mind at ease, they also offer physical reviews performed by their in-house gemologists for free. What happens here is that they can call in your shortlisted diamonds from their suppliers to check for clarity related problems and the diamond’s optical performance.

At the end of the review, they will give you a report and synopsis to follow up on their findings. This will then enable you to make further decisions on buying the diamond based on tangible data.

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One Comment

  1. Matt-
    December 4, 2015 at 9:54 pm

    Hi Paul,

    Thank you for all of the time and effort that you put into this website! I am on the search for an engagement ring for my girlfriend and your site has been so helpful!

    Keep up the great work!!


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