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SI1 Clarity: The Best Value – Only Sometimes

When buying a diamond, you’ll need to consider its Clarity—one of the 4 C’s of diamonds. Clarity refers to the blemishes and inclusions a diamond has. Most diamonds on the market are included, meaning there are small blemishes or imperfections in the stone. Some of these flaws are visible, while others are microscopic.

In evaluating diamonds, you want to find an eye-clean stone without overpaying. As an example, both VS1 and SI1 diamonds can be eye-clean, but the VS1 diamond will be much more expensive. To demonstrate, this 0.9 Carat I color VS1 diamond from Blue Nile costs $3,917, while this 0.9 Carat I color SI1 diamond also from Blue Nile costs $3,142. With the other characteristics of the diamonds being identical, the SI1 diamond is 20% cheaper. Both diamonds are eye-clean, but if you choose the VS1 diamond, you’ll pay ~$700 more.

As shown in the example, an SI1 diamond can save you a good chunk of your budget. But choosing an SI1 diamond isn’t always a good move. Depending on the Carat weight, shape, and particular imperfections in the diamond, an SI1 might not always be eye-clean. In some cases, VS2 clarity is the least expensive, eye-clean option.

In this post, we’ll break down how to know when to choose an SI1. We’ll also include buying tips so you know exactly what to look for. For individual questions about diamond clarity, reach out to our experts.

What does diamond clarity SI1 mean?

SI1 clarity diamonds are Slightly Included to the 1st degree, meaning inclusions can be found with a standard jeweler’s loupe at 10x magnification. With most diamond shapes, SI1 clarity inclusions are almost always eye-clean, meaning you can’t see the imperfections with the naked eye.

In some diamonds, however, you might be able to notice flaws without magnification. The size, color and location of the inclusions play into how noticeable they are. That’s why you need to review each diamond closely. In SI1 diamonds, watch for inclusions like clouds, feathers and crystals. Looking at the diamond up-close with HD imagery, like on James Allen’s site, you’ll be able to tell if the diamond is eye-clean.

Diamond clarity grades – a quick overview

The GIA—the most respected lab grading entity—ranks diamonds on a Clarity scale from best to worst.

The scale is as follows: Flawless (FL), Internally Flawless (IF), Very Very Small Inclusions 1 (VVS1), Very Very Small Inclusions 2 (VVS2), Very Small Inclusions 1 (VS1), Very Small Inclusions 2 (VS2), Small Inclusions 1 (SI1), Small Inclusions 2 (SI2), Inclusions 1 (I1), Inclusions 2 (I2).

While it may seem like buying a flawless diamond would be the best choice, it isn’t necessary. Because imperfections above the SI2 grade are hard to see, you’re essentially overpaying by choosing a better Clarity grade. And sometimes the price difference is significant.

Clarity grades are determined by the size and harshness of an inclusion in relation to the size of a diamond. The grade itself does not tell you whether the inclusions will be noticeable to the naked eye. For example, this 1/2 carat SI1 diamond from Blue Nile has a couple of small grey inclusions visible under the magnification in the image. But if that diamond were on someone’s finger, you would not see that inclusion. On the flip side, take a look at this 3 carat SI1 diamond from Blue Nile. The inclusion is similar to the one in the half-carat diamond (in composition and in its size in relationship to the size of the diamond) but it would be readily visible to the naked eye.

This is important to take into account when reading about clarity grades. This should not scare you off of SI1 grade diamonds. Here is an absolutely stunning 3 carat diamond with an SI1 clarity grade from Blue Nile. You just need to understand that the clarity scale is not black and white.

SI1 Diamond vs VS2 – Example

Let’s put two diamonds next to each other for comparison. Take this eye-clean 0.8 Carat G color SI1 Marquise diamond from James Allen. It costs $2,100. This 0.8 Carat eye-clean F color VS2 Marquise diamond is also eye-clean, but costs $2,560. The color grade is higher, but everything else is the same, and it costs over 20% more. And if you’re looking at SI1 diamonds vs VVS diamonds, the price difference will be even more significant.

With two eye-clean diamonds side-by-side, no matter their clarity grade, you won’t be able to tell the difference unless you’re looking at the diamond under magnification (which isn’t something you’re likely to do with an engagement ring).

Looking at the two diamonds below, can you tell which one is the VS2 and which one is the SI1?

vs2 marquise diamond for SI1 diamond article
SI1 marquise diamond

(The top diamond is the VS2, and the bottom is the SI1.)

This is why a grading report with a clarity grade isn’t enough to make a judgment on whether you should buy the diamond. Take advantage of vendors like James Allen that provide 360° HD imagery.

Clarity Plots on SI1 Diamonds

When you receive a GIA certificate with your diamond, it’ll probably come with a clarity plot (especially if it’s over 1 carat). A clarity plot is a mapping of all of the imperfections in the diamond, including the surface blemishes and internal inclusions. It will show you where and what type of inclusions are present. Because SI1 diamonds are slightly included, the map should have inclusions on it. If the clarity plot of an SI1 diamond doesn’t show anything, there is usually a hidden flaw that affects the clarity grade – there must be a reason why a diamond gets an SI1 grade (e.g. check the comments for “Clarity based on clouds that aren’t shown.” or similar.)

With the clarity plot, notice the locations and type of inclusions. For example, you’ll want to see if the inclusions are near the edge of the stone. If you’re putting the diamond in a pronged setting, it’s likely the inclusions will be covered. If there’s a large inclusion in the center of the table, then the diamond probably isn’t the best purchase.

When SI1 diamonds are the best value

SI1 diamonds will give you the best value for your money in a few scenarios. Here’s a breakdown of the shapes that will usually be eye-clean at the SI1 clarity grade.

Round Cut, Princess Cut diamonds: An SI1 or VS2 clarity grade will typically give you an eye-clean diamond. For large diamonds, we recommend a VS1 or VS2 grade, because the larger the diamond, the easier it is to see inclusions.

Oval Cut, Cushion Cut, Radiant Cut, Marquise and Pear Shapes: These diamonds hide inclusions better than other shapes, so choose an SI1 or even an SI2 diamond to get the best value.

Heart Shaped Diamonds: Opt for an SI1 or VS2 clarity grade, because heart shape diamonds hide inclusions better than Round Cuts, but not as well as shapes like the Cushion Cut or Oval.

Not Asscher Cuts, Emerald Cuts and Baguettes: Step cut diamonds show imperfections easier. Go with a VS2 in these diamond shapes for the best value.

Eye-Cleanliness is Paramount

While this article addresses the technical grading and value of SI1 clarity diamonds, that is not what we recommend focusing on when purchasing a diamond. In our opinion, a consumer’s goal should be to find the cheapest (in regards to clarity; other factors matter as well) “eye-clean” diamond you can find. We use “eye-clean” to describe diamonds that may have inclusions if you look at them with a magnifying glass (or microscope or loupe), but the typical person can’t see the inclusion with their naked eye.

We have recently developed Ringo, a patented artificial intelligence model, that can examine videos of diamonds and determine if they are eye-clean. Ringo will also filter for other parameters like making sure the diamond is well-cut, doesn’t have fluorescence issues and will match the style setting you choose.

    Ringo Approved Eye Clean Diamonds

  • James Allen

    Carat Weight 0.70

    Color I

    Clarity VS1

    Check Price
  • James Allen

    Carat Weight 0.72

    Color I

    Clarity SI1

    Check Price
  • James Allen

    Carat Weight 0.70

    Color I

    Clarity SI1

    Check Price
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If you want to select a diamond specifically for your personal needs (budget, shape and setting style), check it out here

These diamonds look identical in a ring.
Real Diamond Pros will know how to save almost 20%
So Which is it?
The SI1 clarity at $8,600
or the VS1 color at $10,500
Choose the diamond you like better and see if you are a Pro!

Buying Tips for SI1 diamonds

When you shop for diamonds, you’ll have hundreds or thousands of SI1 diamonds to look at. How do you know which SI1 diamond to choose? Follow the expert tips below.

  1. Check to make sure the diamond is eye-clean: This is the most important part of evaluating the clarity of any diamond. Look at the diamond closely using high-tech online imagery. Do you see any imperfections in the stone? If not, it’s eye-clean. If you notice imperfections, it depends on the location and size of them. If a vendor doesn’t have sufficient photos, choose a site that does, like Blue Nile or James Allen.
  2. Look at the clarity plot: Diamonds that are 1 carat or larger should come with a clarity plot on their lab report. You can see exactly where the inclusions are and what type they are.
  3. Notice where the inclusions are: A trick to buying beautiful SI1 diamonds is to find one with inclusions that are spread out. Look out for inclusions that blend into the rest of the diamond or will be covered by the ring setting or prongs.
  4. Aim for faint imperfections: The most obvious inclusions will be dark crystals underneath the table. They look like dust specks that you can’t get rid of. Cloud inclusions, like a cluster of tiny dots, can make the diamond look hazy (hence the cloud name). A feather is a small crack that can impact light reflection, but not if it’s near the bottom of the diamond’s culet (not too close, though). Tiny or faint blemishes won’t be nearly as noticeable as dark ones.
  5. Know your shape: Some diamond shapes hide inclusions well, but not all. The above section “When SI1 diamonds are the best value” gives you a guide on each diamond shape.
  6. Get a reliable certificate: The GIA and AGS are the most reliable lab entities in the industry. You can trust an SI1 diamond from one of these labs because they grade consistently. An SI1 diamond from the EGL or IGI, for instance, won’t mean as much. Because these labs grade inconsistently, an SI1 diamond might actually be an SI2 or an I1 diamond.

Is an SI1 diamond good?

An SI1 diamond can be the best value, depending on the carat weight, shape of the diamond, and the location and type of inclusions. Reviewing a diamond up-close will help you determine if the diamond is eye-clean. If an SI1 diamond is eye-clean, it’s a great purchase because you get a diamond that won’t have any visible imperfections and you aren’t paying for the higher price of a better clarity grade.

Are SI1 diamonds eye-clean?

In many diamond shapes, an SI1 diamond will often be eye-clean. Round Cut diamonds under 1 Carat tend to be eye-clean with an SI1 clarity grade. The same goes for Cushion Cuts, Princess Cuts, Oval Cuts, Radiant Cuts, Marquise and Pear Shapes. For Emerald Cuts, Asscher Cuts, Baguettes and Heart Shaped diamonds, you’ll probably need to go with a VS2 grade to get an eye-clean stone.

What’s better: VS2 or SI1?

In most cases, if you can find an SI1 diamond that’s eye-clean, it will give you better value over a VS2. While VS2 means very slightly included and SI one means slightly included, they’re both often eye-clean—meaning there won’t be any noticeable blemishes and inclusions.

VS2 is technically a better grade, but that doesn’t mean it’s a better diamond. For instance, this 1.0 Carat J color VS2 pear diamond from James Allen doesn’t show any inclusions or blemishes (bowtie aside). It costs $2,210. This SI1 diamond is eye-clean too and costs $2,030.


If you’re getting a beautiful eye-clean stone, it doesn’t matter which you buy, so wouldn’t you want to go for the less expensive one? You can save your money and put it toward a larger diamond or a nicer setting.

How much is a 1 Carat SI1 diamond worth?

A 1 Carat SI1 diamond’s price is based on several factors including its shape, cut quality and color grade. Well-cut 1 carat round diamonds with SI1 clarity and a G-I color can range from $4,000-$5,500. For other diamond shapes, check out James Allen or Blue Nile for estimates.

Final thoughts on SI1 diamonds

An SI1 diamond can give you the best value if you take time to look for an eye-clean stone. Rather than paying for a higher clarity grade, you’re getting an eye-clean diamond for much less. With an eye-clean SI1, no one—except a professional jeweler with a loupe—will be able to tell the difference.

We recommend going with a vendor with HD imagery so you can get a close look at the diamond. James Allen and Blue Nile are the best online vendors to provide all angles of the diamond.

Because finding an eye-clean diamond at the SI1 level can be challenging, feel free to reach out to our experts. We’ll help you find a diamond at the best price.

About the author
Michael Fried
Mike learned the diamond business from the ground-up at Leo Schachter Diamonds - one of the world's top diamond manufacturers. He has been recognized as a diamond industry expert by Time, PeopleMoney, The Daily Mirror, NerdWallet, The Times Herald, Yahoo Finance Australia, The Art of Charm, The Washington Diplomat, The Next Web, and more.
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