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SI2 diamonds can be risky investments, so it takes guts and a great deal of knowledge to find the best diamonds of this clarity grade. However, even though there’s risk, there’s also huge opportunity for finding something of incredible value. But before we get to that, what does ‘SI1’ even mean? 

The term ‘SI2’ refers to the clarity grade of a diamond. Clarity is the term used to describe how free from inclusions or internal blemishes a diamond is. When diamonds are formed over millenia, they naturally pick up these inclusions, which can be unmistakable and unsightly—such as within this 1.04 ct diamond—or they can be much harder to spot, like this 0.908 ct diamond.

Now, most diamonds, even higher gradings such as VVS1 and VS1 have inclusions. In higher grades, these inclusions will be invisible to the naked eye, but in SI2 diamonds, the inclusions will be far more obvious. However, SI2 can too develop without visible inclusions. 

SI2 will naturally be cheaper than diamonds that are ranked Flawless, which makes it harder to find eye-clean diamonds. Overall, the industry generally accepts and estimates that around 70% of SI2 diamonds will contain visible inclusions and therefore not be eye-clean. But don’t be put off—that still leaves a good 30% to search through. 

Here’s everything you need to know about SI2 diamonds. 

  • Why Choose an SI2 Diamond?
  • What is SI2 Grading?
  • What To Look For in SI2 Diamonds
  • SI1 Diamonds vs. SI2 Diamonds

Why Choose an SI2 Diamond?

The initial benefit of an SI2 diamond is the price. They’re far cheaper than higher-graded diamonds, offering you the ability to potentially save thousands of dollars rather than pay the sometimes eye-watering prices that can come with diamonds.

While price is a key point for consideration, you must be able to find SI1 diamonds that are eye-clean, meaning that the inclusions are not noticeable by the naked eye. This is what guarantees that you’re getting a great deal. But under this context, what does an SI1 grade even mean?

What is SI2 Grading?

Clarity grading is the method of sorting diamonds through the number of inclusions they contain. A diamond with many obvious inclusions will rank low and a diamond with few inclusions will rank high—it’s that simple. Today, diamonds are ranked by independent, accredited, and reputable bodies such as the Gemological Institute of America (GIA) or the American Gem Society (AGS). The grading scale you’re most likely to come across is constructed like this:

si2 clarity diamond

Clarity is something determined by a gemologist. They will inspect a diamond, searching for the type, size, and location of any internal blemishes. You will usually find that the bigger the diamond, the bigger or more numerous the inclusions will be. 

What To Look For in SI2 Diamonds?

There are numerous things to look out for when searching for any diamond, but the main considerations should be based around what are known as the Four Cs: Cut, Clarity, Carat, and Color. 

So what should you look for?


The first thing a buyer like you needs to do is search for a diamond that is ‘eye-clean’, meaning that any inclusions that are present can’t be seen by the naked eye. In this case, inclusions can only be seen under 10x magnification, which is how qualified jewelers will inspect their diamonds. 

As we’re already focused on a specific clarity grade, we will explore the other Cs you should be considering. 


Cut is highly important when it comes to the light performance of a diamond, as a poor cut diamond won’t dazzle as well. Essentially, cut dictates how light enters and refracts within a diamond. Cut can actually make the final difference between a good diamond and a superb diamond, even allowing lower clarity diamonds to shine better than high clarity ones. 

Ideal cut diamonds are the highest rank to look for in many diamond circles, but Excellent cuts can also provide a great deal of high-quality light performance. 


It’s not uncommon for some diamonds to have a slight yellow tinge to their bodies. This is obviously not something that a diamond purist will want to invest in, and so color grading will also affect the price and overall quality of the diamond.

We would recommend looking for an SI2 diamond that sits within the F to D color range, such as this 0.70 ct D SI2 Round Cut Loose Diamond. Or this 1.00 F SI2 Carat Round Diamond from James Allen.


Carat is the term used to denote the specific weight of a diamond. Now, this isn’t something you really need to focus on if you’ve already found a good quality SI2 diamond. However, remember that the larger the diamond, the more chance that the inclusions will be obvious. Also make note that the bigger the diamond, the more expensive it will be. 

SI1 Diamonds vs. SI2 Diamonds

SI1 and SI2 both sit in the Slight Included category. However, as you can tell, SI1 diamonds are ranked slightly higher. This is because SI2 tend to have more noticeable inclusions than their counterparts, and SI1 has a higher percentage of potentially eye-clean diamonds. 

That being said, finding a good quality SI2 will still be able to save you hundreds of dollars over the price you would usually pay for an SI1. 

At the end of the day, choosing and SI1 or and SI2 is very much up to personal preference, budget, and the kinds of diamonds you’re able to find. 

SI2 Diamonds: Our Final Thoughts

Evidently, SI2 diamonds are not the best on the market. If you’re looking to invest in one, make sure you do your research and search for the right qualities. Additionally, always go for an eye-clean diamond, and ensure that the stone you’re buying is certified by either the AGS or GIA respectively, as these are two of the most reliable diamond labs in the world. 

Overall, I would recommend choosing an SI1 diamond over an SI2, it’s very difficult to find anything eye clean and the inclusions will be significantly worse than an SI1. Choose diamonds from a retailer such as Whiteflash, who are known for their incredibly high-quality diamonds and their fantastic reputation. You can actually search for SI1 diamonds by clicking on this link. However, Blue Nile and James Allen often have great selections of diamonds that you should consider.

Richard Jenkins, The Diamond Guru

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