The Difference Between Diamond Clarity Grades: VS1, SI1, and Beyond

When purchasing a diamond, clarity is one of the most significant factors affecting the stone’s beauty, value, and overall appeal. 

Clarity refers to the presence of imperfections, known as inclusions (internal flaws) and blemishes (surface imperfections), within the diamond. These characteristics form naturally during a diamond’s creation process deep within the earth.

While some inclusions are microscopic and do not affect the diamond’s beauty, others can reduce its brilliance by interfering with light reflection. 

As a result, clarity grading plays a crucial role in determining a diamond’s price, desirability, and overall quality.

For most buyers, understanding clarity grades, particularly VS1 (Very Slightly Included 1) and SI1 (Slightly Included 1) is essential in making an informed decision. 

Should you opt for a higher-clarity, or is a lower-clarity gemstone and diamond for  better value? This guide explores the differences between VS1, SI1, and other clarity grades, helping you choose the best clarity grade for your budget and aesthetic preference.

What Is Diamond Clarity?

Diamond clarity is a critical factor in evaluating a diamond’s quality, as it refers to the presence (or absence) of imperfections within the gemstone. 

These imperfections are categorized as either inclusions (internal flaws) or blemishes (surface flaws) and can affect the way light travels through the diamond, influencing its brilliance, sparkle, and overall beauty.

What Are Inclusions?

Inclusions are internal characteristics formed during the diamond's natural creation process deep within the Earth. 

These imperfections develop due to extreme heat and pressure, as well as the presence of other minerals or structural irregularities within the crystal.

Types of Inclusions in Diamonds

1. Crystals or Mineral Inclusions

• Tiny crystals of other minerals, such as garnet, spinel, or even another diamond, can sometimes become trapped inside the diamond as it forms.
• These can appear as black, white, or colored specks within the stone.

2. Clouds

• A cluster of microscopic inclusions grouped together, creating a cloudy or hazy area within the diamond.
• Can reduce the diamond’s brilliance if concentrated in one area.

3. Feathers

• Small, feather-like cracks inside the diamond, are often caused by natural formation stress.
• Can impact durability if located near the surface, but is generally harmless if small.

4. Needles

• Thin, needle-shaped crystal inclusions that can be white or transparent.
• Usually invisible to the naked eye and don’t significantly affect the diamond’s appearance.

5. Pinpoints

• Tiny, dot-like inclusions are scattered inside the diamond.
• A single pinpoint is often insignificant, but a cluster of them can form a cloud.

6. Knots

• A crystal inclusion that reaches the diamond’s surface.
• Can sometimes be felt when touching the diamond.

7. Twinning Wisps

• Irregular, ribbon-like formations are caused by crystal distortion during the diamond’s growth.
• Can contain a mix of pinpoint inclusions, clouds, and feathers.

8. Internal Graining

• Structural irregularities inside the diamond appear as faint lines or streaks.
• May affect transparency if they are dense.

What Are Blemishes?

Blemishes are surface imperfections that occur either naturally or during the cutting, polishing, or wearing of the diamond. 

While inclusions are internal flaws, blemishes are external and can sometimes be polished away or minimized.

Types of Blemishes in Diamonds

1. Scratches

• Thin lines or marks on the surface caused by improper handling or wear.
• Can often be polished out by a professional jeweler.

2. Nicks

• Small chips or tiny breaks on the edges or facets of the diamond.
• Can occur due to rough handling or accidental impact.

3. Polish Marks

• Lines or streaks left behind from the polishing process.
• Usually only visible under magnification and do not affect the diamond’s beauty.

4. Pits

• Small holes or depressions on the diamond’s surface.
• Can sometimes be seen without magnification if large enough.

5. Chips

• Small missing pieces on the diamond’s edges or corners.
• Caused by accidental knocks or rough handling.

6. Abraded Facets

• Worn or slightly rough edges on the diamond’s facets.
• Common in older diamonds or stones that have not been well cared for.

7. Naturals

• Small, unpolished areas are left intentionally on the diamond’s surface to preserve weight.
• Typically found along the girdle (the edge of the diamond).

8. Extra Facets

• Additional, unplanned facets are added to correct imperfections or polish away blemishes.
• Usually placed in inconspicuous areas but can sometimes affect symmetry.

How Clarity Affects a Diamond's Appearance & Pricing

While all diamonds have some level of inclusions and blemishes, not all flaws are visible or impact the diamond's brilliance. Here’s how they can influence a diamond’s look:

Transparency & Sparkle:

If inclusions or blemishes block light from passing through the diamond, they can diminish its brilliance and fire (the flashes of color are seen in a diamond).

Eye-Cleanliness:

Some inclusions are only visible under 10x magnification and are not noticeable to the naked eye. Diamonds that appear flawless without magnification are called eye-clean.

Durability:

Large feathers, chips, or fractures near the edges or points of a diamond can weaken its structure, making it more prone to breaking.

Price: 

The rarer the clarity, the higher the price. A Flawless (FL) or Internally Flawless (IF) diamond is significantly more expensive than a VS1 or SI1 diamond.

How Diamond Clarity Is Graded

The Gemological Institute of America (GIA) developed a universally recognized clarity grading scale, which categorizes diamonds based on their level of inclusions and blemishes.

The GIA Diamond Clarity Scale

VS1, SI1, and Their Place on the Clarity Scale

VS1 and SI1 diamonds fall into the middle range of the clarity scale, balancing clarity, beauty, and affordability.

VS1 Diamonds: Near-Flawless Appearance

VS1 (Very Slightly Included 1) diamonds are considered high-quality, with only tiny inclusions that are difficult to detect, even under 10x magnification. 

These inclusions are typically so small that they have no visible impact on the diamond’s brilliance or sparkle. 

Because of their minimal imperfections, VS1 diamonds are almost always eye-clean, meaning the inclusions cannot be seen without magnification. 

This makes them an excellent choice for buyers who want a visually flawless diamond without paying the premium price of Flawless (FL) or Very Very Slightly Included (VVS) diamonds. 

Since the inclusions in VS1 diamonds are often located in inconspicuous areas, such as along the edges or under the facets and they do not affect the overall appearance of the stone.

SI1 Diamonds: A Balance Between Clarity and Value

SI1 (Slightly Included 1) diamonds contain slightly more noticeable inclusions than VS1 diamonds, but they are still considered eye-clean in many cases. 

The inclusions in SI1 diamonds may be larger or more numerous, but their visibility depends on the diamond's cut, shape, and setting. 

A well-cut SI1 diamond can appear identical to a higher-clarity stone because its brilliance and sparkle can help mask small inclusions. 

This makes SI1 diamonds an excellent choice for budget-conscious buyers who want a diamond that looks clean to the naked eye but costs significantly less than VS1 or higher-clarity grades. 

However, it is important to inspect SI1 diamonds carefully, as some may have inclusions that are visible without magnification, especially in larger stones or step-cut shapes like emerald or Asscher cuts, which have open facets that expose internal flaws more easily.

In summary, VS1 diamonds are virtually flawless to the naked eye, making them ideal for those who prioritize clarity. 

SI1 diamonds, on the other hand, provide exceptional value, as they often appear just as clean as VS1 diamonds when chosen wisely. 

If budget allows, VS1 offers peace of mind regarding clarity, while SI1 can be a smart choice for those who want the best balance between price and appearance.

Both clarity grades are popular among buyers who want a balance between quality and cost.

VS1 vs. SI1: Which One Should You Choose

If you’re on a budget, SI1 is an excellent choice. If clarity is a top priority, VS1 may be worth the extra cost.

Can You See the Difference Between VS1 and SI1 Diamonds?

One of the biggest questions buyers have when comparing VS1 and SI1 diamonds is whether the difference in clarity is noticeable. 

The answer depends on several factors, including diamond size, cut quality, and the type and location of inclusions.

In most cases, particularly in round brilliant diamonds and other well-cut shapes, the difference between VS1 and SI1 diamonds is virtually invisible to the naked eye. 

However, under magnification, the inclusions in an SI1 diamond may become more apparent.

Why Do VS1 and SI1 Diamonds Look Similar to the Naked Eye?

The primary reason VS1 and SI1 diamonds often appear identical without magnification is due to how the human eye perceives clarity. 

Most people cannot distinguish between inclusions in diamonds unless they are obvious or positioned in a highly visible area. 

The brilliance and fire of a well-cut diamond also help to mask minor imperfections, making inclusions in an SI1 diamond harder to detect.

Additionally, diamond size affects how visible inclusions are. In smaller diamonds (under 1.0 carat), an SI1 diamond will often appear flawless to the naked eye, as the inclusions are too small to be seen.

Because the inclusions are too tiny to be noticed, an SI1 diamond will often appear flawless to the naked eye.

However, in larger diamonds (above 2.0 carats), inclusions in an SI1 diamond may become more noticeable because they are proportionally larger relative to the stone.

When Is the Difference More Noticeable?

While many SI1 diamonds look identical to VS1 diamonds in everyday viewing conditions, certain situations can make the difference more apparent:

1. Step-Cut Diamonds (Emerald & Asscher Cuts)

Unlike brilliant-cut diamonds, which have many facets that reflect light in different directions (hiding inclusions), step-cut diamonds have large, open facets.

This means inclusions in an SI1 emerald or Asscher-cut diamond are more likely to be visible than in a VS1 diamond of the same shape.

2. Larger Carat Weights

Inclusions are easier to spot in diamonds over 2.0 carats because they scale in size with the diamond.

A VS1 diamond in a larger size will still appear very clean, while an SI1 diamond might show slight imperfections if viewed closely.

3. Types & Locations of Inclusions

If an SI1 diamond has a dark-colored inclusion (black or brown) in the center, it may be more noticeable than a light or white inclusion.

If an inclusion is near the edges (girdle), it may be hidden by the prongs of the setting, making it nearly undetectable.

What About Other Clarity Grades? (VVS1, VS2, I1, etc.)

When considering a diamond, VS1 and SI1 aren’t the only clarity options available. The Gemological Institute of America (GIA) provides a grading scale that includes other clarity grades, each offering different levels of clarity, price, and visual appeal. Understanding how these grades compare can help you make an informed decision.

How Do VVS (Very Very Slightly Included) Diamonds Compare?

VVS1 and VVS2 diamonds are categorized as Very Very Slightly Included and have extremely minimal inclusions that are difficult to detect, even under 10x magnification. These diamonds are:

• Virtually flawless to the naked eye and only an expert with a microscope can spot imperfections.
• Pricier than VS1 or SI1 diamonds, as their rarity increases their value.
  Ideal for collectors or those seeking investment-grade diamonds.

VVS1 vs. VVS2:

• VVS1 diamonds have even fewer and smaller inclusions than VVS2, but the difference is nearly impossible to distinguish without expert tools.

For most buyers, paying for a VVS diamond is unnecessary unless you want a near-flawless diamond for investment or sentimental reasons. VS1 and even SI1 diamonds can look just as clean to the naked eye at a much lower price.

When Should You Consider I1 or Lower Grades?

I1, I2, and I3 diamonds fall into the Included category, meaning their inclusions are easily visible to the naked eye and may affect the stone’s durability. These diamonds are the most budget-friendly but come with trade-offs:

• Inclusions may affect transparency and sparkle.
  Large or dark inclusions can reduce brilliance.
  Potential durability risks if inclusions create internal fractures.

When should you consider an I1 diamond?

• If you’re on a tight budget and don’t mind visible inclusions.
• If the diamond is set in a way that hides inclusions (such as a bezel setting).
• If you prioritize size over clarity, as I1 diamonds allow you to buy a bigger stone at a lower price.

For the best balance of beauty and affordability, SI1 and VS2 diamonds are usually the better choices over I1 or lower grades.

The Best Clarity for Different Diamond Shapes

Not all diamond shapes display inclusions the same way. The cut and facet arrangement play a significant role in how visible clarity imperfections appear. Some diamond shapes hide inclusions better, while others expose flaws more easily.

Why Certain Cuts Hide Inclusions Better

Brilliant-cut diamonds, like round, cushion, and oval cuts, have numerous small facets that reflect light in multiple directions. This makes them excellent at hiding inclusions, as the sparkle and brilliance mask imperfections.

Step-cut diamonds, like emerald and Asscher cuts, have large, open facets that create a “hall of mirrors” effect. These diamonds emphasize clarity, making even small inclusions more noticeable.

Best Clarity Choices by Diamond Shape

Here are the best clarity choices based on their cut type:

Best Clarity for Round Brilliant-Cut Diamonds

• Ideal clarity range: SI1–VS2
• Why? The high brilliance and faceting pattern of round diamonds help mask inclusions, making SI1 a great value choice.

Best Clarity for Emerald-Cut Diamonds

• Ideal clarity range: VS1–VVS2
• Why? The large step-cut facets of emerald-cut diamonds make inclusions easier to see, so a higher clarity grade is preferred.

Best Clarity for Princess-Cut Diamonds

• Ideal clarity range: SI1–VS2
• Why? The sharp, angular corners of princess-cut diamonds can hide inclusions well, but larger inclusions near the edges should be avoided, as they can impact durability.

Best Clarity for Oval, Cushion, and Radiant-Cut Diamonds

• Ideal clarity range: SI1–VS2
• Why? These shapes have brilliant faceting patterns, helping to hide inclusions effectively.

If you are choosing a brilliant-cut diamond, you can opt for lower clarity grades like SI1 without noticeable imperfections. However, if selecting a step-cut diamond, it’s best to choose VS1 or higher for a cleaner look.

Should You Prioritize Clarity Over Cut or Color?

When purchasing a diamond, clarity is important, but it’s not the most important factor. The cut quality of a diamond has the greatest impact on its sparkle and brilliance. A well-cut diamond will appear more radiant and beautiful, even if it has a lower clarity grade.

Here’s a ranking of the 4Cs by importance:

Cut: The most important factor; determines how well the diamond reflects light.

Color: Matters more in larger diamonds; slight color differences can impact value.

Clarity: Important, but many diamonds with lower clarity still look flawless to the eye.

Carat: Determines size, but a smaller, well-cut diamond can appear bigger than a larger poorly cut one.

When Should Clarity Be a Top Priority?

• If choosing a step-cut diamond (emerald, Asscher), clarity is more important, as inclusions are easier to see.
• If selecting a large diamond (2.0+ carats), clarity should be prioritized, as inclusions are more visible in bigger stones.
• If inclusions affect durability, such as cracks or fractures, clarity should be a consideration.

When Can Clarity Be Less Important?

• If choosing a round or brilliant-cut diamond, you can go lower on clarity because the sparkle hides imperfections.
• If on a budget, opting for an SI1 diamond instead of a VS1 allows for more size or a better cut quality.
• If the inclusions are near the edges, they can be hidden by the setting, reducing the need for high clarity.

Tips for Buying a Diamond Based on Clarity

Buying a diamond with the right clarity grade requires balancing appearance, value, and personal preference. Here are some expert tips to help you choose the best clarity for your budget:

How to Choose the Best Clarity for Your Budget

1. If the inclusions aren’t visible to the naked eye, paying for higher clarity isn’t necessary.
2. Make sure you view diamonds in person or request magnified images as this helps ensure inclusions are not in noticeable locations.
3. A well-cut SI1 diamond will often look better than a poorly cut VS1 diamond.
4. Clarity-enhancing settings such as Halo, bezel, or prong settings can help mask inclusions.

How to Spot a Good Deal Without Overpaying

Prioritize "Eye-Clean" Diamonds in the SI1 or VS2 Range

For the best balance of quality and price, focus on diamonds with SI1 or VS2 clarity grades that are "eye-clean." 

These grades represent diamonds with slight inclusions (SI1) or very slight inclusions (VS2). The key here is "eye-clean," meaning that the inclusions are not visible to the naked eye when you look at the diamond normally. 

Diamonds in these clarity ranges offer exceptional value because they deliver a beautiful, inclusion-free appearance to the unaided eye while being more affordably priced than the higher, internally flawless grades.

Strategically Consider Inclusion Placement Near the Edges

When examining a diamond's clarity, check if any inclusions are located near the edges, also known as the girdle. 

Inclusions positioned closer to the girdle are often less noticeable when viewing the diamond from the top and can even be cleverly hidden once the diamond is set in a ring or other diamond jewelry. Choosing a diamond with inclusions in these less prominent areas is a smart way to maximize visible beauty while being more mindful of your budget.

Be Mindful of Inclusions That Could Impact Durability

While seeking value, it's crucial to avoid inclusions that could potentially compromise the diamond's durability over time. 

Be cautious of inclusions like feathers, cracks, or black inclusions, especially if they are located near the edges or corners of the diamond. 

These types of inclusions, in vulnerable locations, could potentially increase the risk of chipping or breakage with everyday wear. When in doubt, always consult with a trusted jeweler at Leon Diamond who can assess the stability of any diamond you are considering.

Always Insist on Certification from Reputable Labs

To ensure you are getting an accurate assessment of a diamond's clarity grade and overall quality, always purchase diamonds that come with a certification from a reputable gemological laboratory, such as GIA (Gemological Institute of America) or AGS (American Gem Society). 

These labs are known for their stringent and consistent grading standards. A GIA or AGS certification provides you with confidence and assurance that the clarity grade assigned to your diamond is accurate and reliable, protecting your investment and ensuring you receive the quality you expect.

Discover Your Perfect Diamond Today

Ultimately, understanding the nuances between VS1 and SI1 diamonds empowers you to make a truly informed and confident choice. While VS1 diamonds offer exquisite, near-flawless perfection, SI1 diamonds present an exceptional sweet spot of beauty and value. The ideal choice truly depends on your individual priorities, budget, and how much premium you place on absolute clarity.

Ready to explore diamonds and find the perfect clarity grade for your dream jewelry? Visit Leon Diamond today to browse our extensive collection of VS1 and SI1 diamonds. 

Our expert gemologists are here to guide you, answer your questions, and help you select a diamond that perfectly balances beauty, value, and your unique preferences.