What is an SI3 Diamond, and am I Getting Scammed?

What is an SI3 Diamond and am I getting Scammed?

If you scour the internet you will see many articles saying that the SI3 grade is a scam  they go on to say it is just a way for jewelers to make more money, and these diamond are just really I1’s.

I tend to believe those people that wrote those articles know little about the business and how things are priced. They may understand the diamond grading system, but have little knowledge of how diamonds are purchased at a wholesale level.


GIA Grading

First of all, GIA came up with a diamond grading system that grouped diamonds in to categories based on the amount of inclusions and where they are located in the diamond.  If you take a look at their clarity scale on one of their certificates you will see there is a “range” for each category.  Also, you will see the further down the scale the larger the “range” for each of those categories.

gia clarity grading ranges
gia ranges for clarity grading





smaller rang for VS


larger range for SI








VS Clarity

What that means to a dealer is the  a flawless diamond is flawless. There is not a “good” flawless and “bad” flawless graded stone.  The range for VVS is very small. As we get into the VS range the range is wider. That means you can have a borderline VS2. It could be both border line up to a VS1, or border line down to an SI1.

SI1 Scale

Now, take a look at the SI scale.  You will see there is a pretty big “range.”  This means to a dealer, we cannot buy an SI2 without looking at the diamond.  In dealer to dealer buying it is common to say “how is the SI1” or “how is the SI2” because we know there is a big range in the SI category.

If you take the grading scale literally, it basically says SI graded diamonds are eye clean, and I1 diamonds are not.  Again, if you understand the grading system this may be black and white.  If you are a dealer you understand that this depends on the size of the diamond, type of inclusion and where it is located in the diamond.

For example if I have a 5ct diamond with a black carbon inclusion on the table, it may be visible to the naked eye. If the same inclusion, scaled to the smaller size of a 1ct, it will not be visible to the naked eye.

Understanding I1

Below you will see some plots of diamonds all graded I1. You will see that some inclusions will be very obvious to the naked eye. Some, where the inclusions are smaller and scattered will not be obvious to the naked eye.  

I1 grading
industry standards for I1 grading

Let me pose a question… If all these diamonds were all priced the same would you prefer to take diamond 1 or 2, or would you be just as happy with diamond 3 or 4 where the inclusion are very noticeable to the naked eye??

The reality is, having everything else equal, no one would choose the diamond with the obvious eye visible inclusions. When a dealer inspects a parcel of I1 graded diamonds we separate those stones into 2 piles.  One eye clean and one not eye clean. We charge a premium for the eye clean diamonds and a discount for the not eye clean diamonds.  It is those eye clean I1’s that we categorize as SI3.

As dealers, and you as a consumer, would pay more for those eye clean stones we cannot consider them all the same grade. This is how the SI3 category is used.

Now you are knowledgable and will be able to decide if you want to buy an SI3 diamond. In our business these are a very common diamond purchases, because of the value. They are less expensive then SI2’s, but still eye clean.

Have questions about SI3 diamond? Well any  quality, feel free to speak with one of our diamond experts. Houston Diamond Outlet buys from sight holders on a daily basis. We also understand what goes into grading and  valuing a diamond. We would love help you choose the diamond that is best for you.

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