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Diamonds are assigned a clarity grade based on the presence of inclusions, which are blemishes within their facets.
SI (slightly included) and VS (very slightly included) are two grades on the clarity scale. These categories are broken down into SI1, SI2, VS1, and VS2.
The main difference between SI and VS diamonds is SI diamonds have larger inclusions that affect their appearance, durability, and brilliance. VS diamonds have inclusions that are more easily visible with magnification but often not noticeable to the naked eye, which is why they’re a popular choice for engagement ring diamonds.
When I was shopping for an engagement ring for my now-wife, eye-cleanliness was a priority. For that reason, I chose a VS1 diamond without visible inclusions.
We’ll compare SI versus VS diamonds, including an overview of each clarity grade, the three differences, and how to decide which is right for you.
What are SI Diamonds?
SI diamonds are assigned that clarity grade because the inclusions are easy to identify, and there are often many types found inside their facets.
When gemologists are determining a diamond’s clarity, they’ll use a jewelers loupe with 10x magnification to scan back and forth over the diamond. For diamonds toward the top of the scale, like VS1 or VVS1, they may not notice flaws with a quick glance.
This isn’t the case with SI diamonds. Some of the inclusions they’ll find include:
- Twinning wisps
- Etch channels
They’ll often be scattered across the diamond’s table and pavilion.
For example, this one-carat diamond from Blue Nile earned an SI1 clarity grade. The GIA report notes six types of inclusions in its facets, including surface graining.
The top-down and bottom-up view on the clarity characteristics plot confirm inclusions are visible at almost every angle.
The high-resolution image confirms the information on this SI2 diamond’s report. Inclusions are visible in multiple places.
To further distinguish the extent of inclusions, the GIA scale divides the SI category into SI1 and SI2.
SI1 and SI2 Clarity
SI1 is the higher clarity grade within the SI diamond category.
It’s often the minimum clarity grade buyers choose for an engagement ring diamond because small SI1 diamonds can appear eye-clean.
As an example, there aren’t any inclusions visible in this image of a 0.75-carat diamond from James Allen. We suspect it’s eye-clean, but the only way to tell is to view it in person.
SI2 is one position below SI1 and one above the included category, abbreviated “I”.
Even small SI2 diamonds often have visible inclusions, so they aren’t a popular choice for engagement rings. It’s often the lowest clarity grade available from diamond retailers.
You’ll typically find a high number of inclusions, and many are large. If the report notes only one or two flaws, know they’re likely significant in their size and impact.
What are VS Diamonds?
VS diamonds are toward the middle of the GIA clarity scale. They’re one position below very, very slightly included (VVS) and above SI.
Diamonds are assigned this clarity grade because inclusions are often easy to spot at 10x magnification but generally invisible to the naked eye.
VS diamonds also feature the same kinds of inclusions found in other clarity grades. There may be a white twinning wisp near its crown, several pinpoints on its table, or a small etch channel.
As an example, this 0.76-carat diamond has clouds, needles, and pinpoints.
These are some of the same inclusions as the SI diamonds above, but they’re smaller and in less prominent positions.
VS diamonds are often used in engagement rings. In fact, if you’re choosing a diamond heavier than one carat, you could start your search in this category.
Similar to the SI category, VS clarity is also broken down into VS1 and VS2.
VS1 and VS2 Clarity
VS1 is one clarity grade higher than VS2 and one below VVS2.
It’s the clarity grade I chose because I wanted a diamond that was eye-clean at a strong value. VS1 diamonds often meet this criteria.
When a gemologist is assessing a VS1 diamond, they may have to scan back and forth a few times before identifying all the inclusions.
Small ones like pinpoints or faint black spots aren’t always immediately noticeable in these diamonds.
The image below of a VS1 diamond engagement ring is a helpful example.
It has common types of inclusions but appears eye-clean.
The inclusions in a VS2 diamond are slightly more frequent or impactful than ones in VS1 diamonds.
They aren’t as difficult to identify with a jewelers loupe and are sometimes located in each area of the diamond, from its table and crown to the pavilion.
VS2 is often the right starting point for fancy shapes like emerald and princess cuts because they don’t disguise inclusions as well as round cuts.
What are the Differences Between SI and VS Diamonds?
If you’re comparing the qualities of SI versus VS diamonds, you should understand the distinctions between these types of diamonds.
It’s an important consideration, whether you’re searching for the center diamond on an engagement ring or smaller diamonds to enhance another piece of jewelry.
Here are the three differences between SI and VS diamonds.
1. SI Diamonds Often Have a Higher Amount of Inclusions
In most cases, SI diamonds have more inclusions than ones that earn a VS grade.
The total number of inclusions is only one consideration in designating clarity, but if the inclusions are a similar size and type, the total number could sway the final grade higher or lower.
The VS2 diamond has the following inclusions:
- Indented natural
The SI2 diamond has eight, including all the ones present in the VS diamond, plus:
- Twinning wisps
A higher amount of inclusions has a negative impact on the diamond. It’s rare to find one with more than six types that earns above an SI grade.
But there are exceptions to this general rule. We’ve seen diamonds earn a SI2 grade because of a single crystal that affected every aspect of its appeal.
2. VS Diamonds are More Likely to be Eye-Clean
Most buyers aren’t concerned about the exact number and type of inclusions present in their diamond. Instead, they focus on how it appears to the naked eye.
After all, no one besides the gemologist will view it under magnification, so how the inclusions look under a jewelers loupe often doesn’t impact the decision.
That’s why buyers often start their search with VS diamonds. They have a higher likelihood of appearing eye-clean if they’re less than two carats.
The inclusions present within their facets are often small, white, or transparent. Large black spots or dark crystals often result in an SI1 or SI2 grade.
This diamond engagement ring features a 1.5-carat VS1 diamond.
Its inclusions aren’t visible in the high-quality photos despite its high carat weight.
Choosing an eye-clean VS diamond over a VVS or flawless diamond results in significant cost savings. I created the same engagement ring as the one above but with a VVS1 diamond, and the cost is almost 40 percent higher.
So my recommendation is to prioritize eye-cleanliness instead of an exact clarity grade. You can start by examining SI diamonds, but you’ll often find yourself moving up to VS clarity grades.
3. SI Diamonds are Less Expensive
The reason buyers choose diamonds on the low end of the clarity scale is they’re less expensive. But I caution buyers all the time to not sacrifice eye-cleanliness to save on price.
There’s higher demand for ones with fewer flaws because of the way inclusions affect every aspect of the diamond.
The cost also increases because diamonds with minimal imperfections are rare.
To best understand the differences in price between VS and SI diamonds, we compared prices of 173 round-cut diamonds from James Allen.
They all have the following qualities:
- Carat weight: 0.9
- Color: F
- Cut: Very good
Diamonds with SI2 clarity sold for an average of $3,711, with a range of $2,880-$4,630.
For SI1 clarity, the average price was $4,662, and the range was $4,110-$5,240.
For VS2 clarity, the average was $5,689. They were priced between $4,900-$7,190.
VS1 clarity diamonds with those qualities average $6,118 and range from $4,930-$7,030.
This data demonstrates SI diamonds are less expensive than ones graded VS.
Each step up the clarity scale increases the price by between 15 and 25 percent.
So by finding an eye-clean diamond with a lower clarity grade, you can put that savings toward improvements in other qualities like its carat weight, color, or cut grade.
Should You Choose an SI or VS Diamond?
Choosing between an SI versus VS diamond involves understanding how inclusions determine its price and performance, whether it’s for an engagement ring or another piece of jewelry.
Here are some tips to help you decide.
You should consider an SI diamond if:
- You’re choosing a diamond that’s less than one carat
- You view it in-person or through high-resolution images before you buy it, so you can learn whether its inclusions are noticeable
You should opt for a VS diamond if:
- You want an eye-clean diamond that avoids the premium prices for higher clarity grades
- You’re choosing a fancy cut, where the facets don’t hide inclusions in the same way as round cuts
My recommendation is to choose a VS2 or VS1 diamond but to start your search at SI1. If you find an eye-clean SI1 diamond, you’ve found exceptional value.
By comparing SI versus VS diamonds at in-person and online vendors, you’ll find the perfect ring for you.
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