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I vs. SI Clarity Diamonds: How are They Different?

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I vs SI Diamond Clarity

Clarity is a foundational consideration in any diamond purchase. It refers to the extent of inclusions, or flaws, found in a diamond and how they affect its appearance, durability, and brilliance.

Organizations that certify the quality of diamonds assign a clarity grade, where flawless is the highest and I3 is the lowest.

If you’re comparing I (included) versus SI (slightly included) diamonds, it’s important to understand how these grades impact its overall quality.

Let’s examine I and SI diamond clarity, including the specific grades within each category and how they compare in areas such as inclusions, prices, and popularity.

What is I Clarity Diamond?

I clarity diamonds have a significant number of inclusions that affect the diamond’s appearance and light performance. Its grade is a result of the inclusions being easily visible with a jeweler’s loupe at 10x magnification, but they’re almost always visible to the naked eye.

I1 Clarity Diamond

The imperfections are often ones that have more influence on the diamond’s quality. Inclusions such as pinpoints, needles, and internal graining rarely negatively affect a diamond. 

Twinning wisps, dark crystals, and cavities are more noticeable and likely to diminish brilliance.

The latter are the ones found in I clarity diamonds, where the former group is more often in VVS (very, very slightly included) diamonds. It’s a combination of problems where not only are there more inclusions present, but they’re more impactful as well.

The included category is broken into three subcategories: I1, I2, and I3.

I1: I1 is the highest grade in the included category. It’s uncommon to find an eye-clean I1 diamond, but if it’s under 0.5 carats, the inclusions may be small enough to avoid detection by the naked eye. This is why I1 diamonds are used for side stones, accents, or to line a pave band.

I2: The inclusions in an I2 clarity diamond are easily visible without magnification. They’re filled with a few large inclusions or many smaller ones, resulting in minimal glimmer and the potential to chip or break. The types of inclusions include clusters of dark crystals, black spots, or widespread graining, which is why they aren’t used as the center stone in engagement rings.

I3: I3 is the lowest clarity grade a diamond can receive. The inclusions are highly visible, and it may even look like a salt and pepper diamond. If you’re at all concerned about its appearance to the naked eye and durability, you should avoid I3 diamonds any larger than half of a carat. It’s vulnerable to breaking and will have obvious inclusions to anyone viewing it.

Even though I clarity diamonds score lowest on clarity, they can be right for some situations. You can save money by using them as part of the setting and investing those savings into a higher carat or clarity for the center diamond.

What is SI Diamond Clarity?

SI diamond clarity is between VS (very slightly included) and I. The small inclusions are visible at 10x magnification. To the naked eye, some SI diamonds are clean while others have noticeable inclusions. The determining factor is the size of the diamond and type of inclusions.

SI Diamond Clarity

Commons inclusions present in SI diamonds are:

The SI category can be broken down into SI1 and S12.

SI1: In most cases, you can’t see the inclusions in an SI1 diamond without magnification. This is dependent on the size of the diamond and its inclusions, but SI1 is considered the lowest clarity grade that still passes as eye-clean. Before you buy an SI1 diamond, examine it in-person or through high-resolution photos online.

SI1 Clarity Diamond

SI2: It’s possible to find an SI2 diamond without visible inclusions. This presents the opportunity to find tremendous value because the SI2 grade significantly lowers the price. When inclusions are visible, they’ll be darker compared to SI1. If you can’t find an eye-clean, SI2 diamond, search for one where the inclusions are near the edge so they can be covered by the setting.

Diamonds with SI clarity are used for both the center diamond in engagement rings and as accents. 

It’s more popular to see SI1 diamonds in the middle than SI2 because of their cleanliness to the naked eye and better light performance.

How Do I and SI Diamonds Differ?

Even though I and SI are next to each other on the GIA clarity scale, there’s a difference in their overall quality and what you should expect to pay for each. Let’s compare I versus SI diamonds across inclusions, cost, and the variety of options available for each.

I Diamonds Have More Inclusions

I and SI are designations of inclusions, so the primary difference between the two are the number, type, and visibility of these imperfections. 

Inclusions detract from the value because they diminish its appearance, brilliance, and durability, so each grade a diamond moves down the clarity scale often impacts all three.

If you placed two diamonds next to each other, one an S1 and the other an I3, you’d easily distinguish them because the inclusions in the I3 diamond would be more noticeable. It may have a feather visible through the crown, a black spot on a facet, or an indented natural that dips below the polished surface.

Indented Natural

The SI1 diamond, on the other hand, may have visible inclusions but could also appear eye-clean. 

The inclusions would be smaller and in less prominent positions on the diamond compared to the included one.

The differences are less obvious if the grades are only one apart. For example, it could be difficult to identify an S1 versus S12 diamond or an I1 versus I2. 

Though you can find reliable grading through organizations such as the GIA or AGS, there’s some degree of subjectivity in every designation because even trained gemologists may differ on whether a certain inclusion warrants one grade or the other.

I Diamonds are Less Expensive

All else being equal, diamonds with I clarity grades are less expensive than SI diamonds. The price of a diamond increases as its quality moves up the grading scale, so the SI grade results in a more expensive diamond.

The best way to compare the prices of I versus SI diamonds is to identify diamonds where other qualities are the same, except for its clarity grade.

For example, let’s compare the prices for diamonds from James Allen with the following qualities:

  • Carat: 1.00
  • Cut: Very Good
  • Color: G

For included diamonds, the average price is $3,210. The range is $2,120-$4,440.

Average Price of I Diamonds

For SI diamonds, including both SI1 and SI2, the average price is $3,910. The range is $2,300-$5,570.

The average difference in price between those I and SI diamonds is 18 percent. The difference between the SI diamond with the highest price, and the I diamond with the lowest price is $3,450 — a savings of 61 percent.

This demonstrates how significant of an impact the clarity grade has on the overall price, even when everything else about the diamond is almost exactly alike.

These prices play out across most diamond retailers. As another example, the average price for a diamond with the following characteristics from Brilliance is $2,627:

  • Carat: 1.00
  • Cut: Very good
  • Color: H
  • Clarity: Included

The average price for a diamond with those traits, except an SI clarity, is $3,978. That’s an increase of 51 percent.

Average Price of SI Diamonds

This shows the cost savings associated with lower clarity diamonds. It allows you to instead put that money toward other parts of the piece, whether the shank or additional diamonds.

I Diamonds are Less Popular at Retailers

If you’re searching the most popular diamond retailers online or in-person, you’re more likely to find a variety of options available for SI diamonds. You can filter by carat, color, and cut, and you’ll be presented with dozens or hundreds for each grade or weight.

The same cannot be said about I diamonds. In fact, many of the most popular retailers don’t sell diamonds below I1, and some avoid selling included diamonds at all.

For example, James Allen sells loose diamonds at each clarity grade down to I1 but doesn’t include I2 or I3 diamonds. They would sell for a low price, and many retailers want to avoid selling diamonds loaded with inclusions.

Blue Nile, another leading online retailer, doesn’t sell I diamonds. Instead, the lowest clarity you can buy is SI2. Brian Gavin is the same, where their inventory stops at SI2.

Clarity Scale

As a prospective diamond buyer, you want the maximum amount of options so you can prioritize the qualities that are most important to you. Choosing a SI diamond versus an included one gives you these choices.

Do I and SI Diamonds Have any Similarities?

Even though there are many differences in comparing I versus SI diamonds, the categories do have similarities. 

SI1 Clarity Diamond

The first similarity is the inclusions affect their brilliance. The most impactful trait of a diamond in regard to brilliance is its cut, but blemishes do prevent light from entering and exiting at the right angles. 

You can expect diminished brilliance as a result of inclusions for both I and SI diamonds, though it will be more pronounced at the lower end of included ones.

Additionally, there can be concerns about chipping. Chip inclusions can be present in SI diamonds, and any small chip leaves the diamond susceptible to future ones. They’re even more prevalent in I diamonds. 

In fact, a diamond that’s otherwise clean may be downgraded to an I because of a large chip. That inclusion is more impactful than several small ones, so it could warrant a drastic drop in clarity.

The other commonality is the visible inclusions. Clarity grades above SI are almost always eye-clean, but many SI diamonds aren’t. It’s a rare instance in which included diamonds have no visible inclusions. 

Is an I or SI Diamond Right For You?

I vs SI Clarity Infographic

If you’re searching for an engagement ring’s center diamond, you shouldn’t choose one with an I clarity grade. The center diamond is the most prominent part of the ring, so you don’t want visible inclusions.

Instead, you should opt for one graded SI1 or above. If it’s an SI1, view it in-person under strong lighting or in a quality photo online. There are many that are eye-clean, but you won’t know for sure based on its grade.

If you’re looking for diamonds to complement the main one as accents or pave, I diamonds are sufficient. 

They’re often too small to see any of the inclusions, and their lack of brilliance won’t cause the piece to appear dull. You can save money on these smaller diamonds and increase the quality or size of the center one.

By exploring all the options available with I and SI diamonds, you can find the one that’s the right fit for you.

Devon Tyler

Devon Tyler

Devon Tyler is the founder of TeachJewelry.com.

He earned an Applied Jewelry Professional Diploma from the Gemological Institute of America and now brings you essential information about diamonds, settings, and more.

Devon has consulted with leading jewelry brands, and his work has been cited in Diamond Nexus and other industry publications.

He's also a member of the International Gem Society.

Devon enjoys discussing jewelry with readers, so contact him with any questions at tyler.devon@teachjewelry.com.

Learn More About Devon

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