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 costs $3,917, while this 0.9 Carat I color SI1 diamond 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.
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.
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.
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. 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 one 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?
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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