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Diamond Clarity Guide: Grades, Inclusions and What Actually Matters
Of all the 4Cs, clarity is the one most buyers overspend on. Unlike cut, which directly determines how brilliant a diamond looks, or colour, which affects the visible warmth of a stone, clarity is largely about characteristics that exist below the surface, characteristics that, in most clarity grades, you will never see with the naked eye.
This is where the concept of an eye-clean diamond becomes so important. A diamond does not need to be flawless to be beautiful. It simply needs to be free of inclusions visible to the unaided eye. Understanding that distinction is worth hundreds sometimes thousands of pounds.
In this guide, you will learn exactly what diamond clarity means, how the grading scale works, which grades represent genuine value, and how to use clarity strategically to get a more beautiful diamond for your budget.
What Is Diamond Clarity?
Diamond clarity refers to the absence of internal characteristics (called inclusions) and surface characteristics (called blemishes). Almost all diamonds contain some degree of natural imperfection traces of the extreme heat, pressure, and geological turbulence that created them over billions of years. These characteristics are part of what makes each diamond unique.
Clarity grading assesses these characteristics under 10x magnification and assigns a grade based on the number, size, position, nature, and relief (visibility) of any inclusions or blemishes present. The higher the clarity grade, the fewer and less visible the characteristics.
Types of Inclusions and Blemishes
Understanding what graders are actually looking for helps you interpret a clarity grade with confidence. Inclusions are internal; blemishes are on the surface.
Common Inclusions (Internal)
| Inclusion Type | What It Is |
|---|---|
| Crystal | A mineral crystal trapped inside the diamond during formation. Can appear as a white, black, or coloured dot |
| Feather | A small fracture or crack within the diamond. Usually white and wispy in appearance. Large feathers can affect durability |
| Cloud | A cluster of very small pinpoints too tiny to distinguish individually. Can create a hazy appearance in larger concentrations |
| Pinpoint | A tiny crystal inclusion that appears as a small dot under magnification. Very common and usually harmless |
| Needle | A long, thin crystal inclusion. Usually white or transparent and less visible face-up |
| Twinning Wisp | A series of inclusions formed at the boundary between two crystal growth directions. Can appear as a ribbon of inclusions |
| Cavity | A surface opening into the interior of the diamond. Can trap dirt over time if large |
| Knot | A crystal inclusion that extends to the surface. Visible as a raised area on a facet |
The Diamond Clarity Grading Scale
GIA (Gemological Institute of America) developed the clarity grading scale that is now used universally across the industry. It has eleven grades across six categories, assessed under 10x magnification by a trained grader:
| Grade | Category | Eye Clean? | What It Means |
|---|---|---|---|
| FL | Flawless | Yes completely | No inclusions or blemishes under 10x magnification |
| IF | Internally Flawless | Yes completely | No inclusions; minor surface blemishes only |
| VVS1 | Very Very Slightly Included | Yes | Inclusions extremely difficult to see under 10x |
| VVS2 | Very Very Slightly Included | Yes | Inclusions very difficult to see under 10x |
| VS1 | Very Slightly Included | Yes | Inclusions difficult to see under 10x; invisible to naked eye |
| VS2 | Very Slightly Included | Yes (almost always) | Inclusions somewhat easy to see under 10x; rarely visible to naked eye |
| SI1 | Slightly Included | Usually | Inclusions easy to see under 10x; visible to naked eye in some stones |
| SI2 | Slightly Included | Sometimes | Inclusions very easy to see under 10x; often visible to naked eye |
| I1 | Included | No | Inclusions obvious under 10x and visible to naked eye; may affect brilliance |
| I2 | Included | No | Inclusions clearly visible to naked eye; affect brilliance and durability |
| I3 | Included | No | Inclusions very obvious; significantly affect appearance and structural integrity |
What Each Clarity Grade Looks Like in Practice
FL and IF — Flawless and Internally Flawless
Flawless and Internally Flawless diamonds are exceptionally rare and command a significant price premium. Under 10x magnification, a trained grader can find nothing to fault. To the naked eye, they are indistinguishable from a VS1 or even a well-chosen SI1.
FL and IF diamonds are purchased primarily by collectors and investors, or by buyers for whom owning the finest grade available is a matter of principle. If your goal is a beautiful engagement ring that looks stunning on the hand, you are paying a very substantial premium for characteristics that will never be seen in normal wear.
VVS1 and VVS2 — Very Very Slightly Included
VVS diamonds contain inclusions so minute that even experienced graders find them challenging to locate under 10x magnification. They are completely eye-clean and, in practical terms, visually identical to Flawless diamonds when worn.
VVS grades are a meaningful step down in price from FL/IF and still represent excellent quality. They appeal to buyers who want near-perfection on paper without paying the Flawless premium. That said, the difference between VVS and VS is also invisible to the naked eye so even VVS carries a premium that does not translate into visible beauty.
VS1 and VS2 — Very Slightly Included
VS clarity is the sweet spot for most engagement ring buyers in the UK. Inclusions are present but difficult to locate even under magnification, and they are essentially never visible to the naked eye in VS1 or VS2 stones. VS diamonds look flawless in everyday wear while representing significantly better value than VVS or above.
VS1 sits slightly above VS2 inclusions in VS1 are harder to find and typically smaller. In practical terms, both grades produce diamonds that are indistinguishable from each other to the naked eye. VS2 is typically the better value choice: the same visible appearance for less money.
SI1 and SI2 — Slightly Included
SI clarity grades are where the decision becomes more nuanced. Inclusions in SI diamonds are easy to find under magnification but whether they are visible to the naked eye depends entirely on the specific stone: the nature, position, and size of the inclusions.
SI1: Many SI1 diamonds are eye-clean inclusions are present under the loupe but not visible without one. A well-chosen SI1 from a reputable source, viewed in person or via high-resolution video, can offer outstanding value. This is where knowing what to look for pays off.
SI2: SI2 is more variable. Some SI2 diamonds are eye-clean; many are not. Inclusions that affect the face-up appearance of the stone are more common at this grade. We recommend always viewing an SI2 diamond face-up before purchasing, and seeking a grader’s second opinion if buying online.
The key variable in SI grades is inclusion position. An inclusion in the corner or near the girdle of a diamond is far less visible than one directly under the table (the central flat facet). A black crystal inclusion under the table of an SI1 is very different from a white feather near the girdle of another SI1.
I1, I2 and I3 — Included
Included diamonds contain inclusions visible to the naked eye. At I1, inclusions are clearly present if you look for them but may not dramatically impact the appearance of the stone in casual viewing. At I2 and I3, inclusions are obvious and can affect both the brilliance and structural integrity of the diamond.
We do not recommend I-grade diamonds for engagement ring centre stones. The visual impact of visible inclusions is significant, and in I2 and I3 stones, the long-term durability of the diamond can be a concern if feathers or fractures are present.
The Eye-Clean Concept: The Most Important Clarity Rule
Eye-clean is the most useful concept in diamond clarity buying, and it is not a technical term you will find on any certificate. It simply means: the diamond has no inclusions visible to the naked eye in normal viewing conditions.
A diamond does not need to be Flawless to be eye-clean. Most VS1, VS2, and many SI1 diamonds are completely eye-clean. The practical implication is straightforward: if two diamonds look identical in normal wear one graded VS1 and one graded SI1 the SI1 represents significantly better value.
Factors That Affect Eye-Cleanliness
Position of inclusions: Inclusions under the table (centre of the stone) are more visible than those near the girdle or pavilion. Edge and corner inclusions are often masked by the setting prongs
Nature of inclusions: White or transparent inclusions are far less visible than dark or black crystals. A white feather is much harder to spot than a black crystal of the same size
Size and number: A single pinpoint differs vastly from a cluster of crystals or a large feather, even within the same clarity grade
Diamond shape: Brilliant-cut shapes (round, oval, cushion, pear) scatter light in ways that mask inclusions. Step-cut shapes (emerald, Asscher) are more transparent and reveal inclusions more readily
Carat weight: Inclusions become more visible as carat weight increases, because the facets are larger. An SI1 that is eye-clean at 0.80 ct may not be eye-clean at 1.50 ct in the same position
How Clarity Affects Diamond Prices
Clarity has a meaningful impact on diamond prices, particularly at the higher end of the scale. Here is a general sense of how clarity grades affect cost within the same carat and colour parameters:
Clarity Recommendations by Diamond Shape
| Shape | Minimum Recommended | Notes |
|---|---|---|
| Round Brilliant | SI1 (eye-clean) | Brilliant facets scatter light and mask inclusions well. A well-chosen SI1 is often indistinguishable from VS2 |
| Oval | SI1 (eye-clean) | Similar to round; brilliant faceting masks inclusions. Always verify eye-clean status |
| Cushion | SI1 (eye-clean) | Large open facets can show inclusions more than round; review face-up carefully at SI1 |
| Emerald | VS2 minimum | Step-cut facets are transparent; inclusions are far more visible. Recommend VS1 or higher for larger stones |
| Princess | VS2 minimum | Corners can concentrate inclusions; check that inclusions near corners are not structural |
| Pear | SI1 (eye-clean) | Brilliant faceting helps mask inclusions; check the tip and shoulders carefully |
| Marquise | SI1 (eye-clean) | Brilliant faceting helps; check both tips and the centre for bowtie-adjacent inclusions |
| Asscher | VS1 minimum | Highly transparent step-cut; inclusions are very visible. VS1 or VVS2 recommended |
| Radiant | SI1 (eye-clean) | Brilliant faceting makes it forgiving; similar approach to oval and cushion |
| Heart | VS2 minimum | The open table area and distinct silhouette make inclusions near the centre more visible |
Smart Clarity Buying Strategies
Strategy 1: Start At VS2 And Work Down
Rather than beginning with the highest clarity grade and compromising, start at VS2 the grade where diamonds are reliably eye-clean and only move to SI1 if you are able to verify the specific stone is eye-clean. This approach means you never overpay for invisible characteristics, but you also never risk a stone with visible inclusions.
Strategy 2: Always Verify Eye-Clean Status For SI Grades
Never purchase an SI1 or SI2 diamond purely on the basis of the grade on the certificate. The clarity grade tells you that inclusions exist and roughly how visible they are under magnification it does not tell you whether those inclusions are visible face-up in normal wear. Always ask your jeweller directly, or request a face-up video of the stone in daylight conditions.
Strategy 3: Use Inclusion Position To Your Advantage
The same clarity grade covers a wide range of inclusion positions. An SI1 with a small white inclusion near the girdle which will be partly covered by a prong in the setting is a very different stone from an SI1 with a dark crystal directly under the table. When evaluating SI diamonds, ask where the inclusions are located and how they will interact with the setting.
Strategy 4: Save On Clarity, Invest In Cut
Clarity is where buyers most commonly overspend relative to the visible return. If you are choosing between a VVS1 with a Very Good cut and a VS2 with an Excellent cut, the VS2 Excellent cut will almost always look more beautiful. The extra brilliance from the superior cut far outweighs the marginal clarity difference both of which are invisible to the naked eye.
The money saved by stepping from VVS to VS2 can fund a meaningful improvement in cut quality, a larger carat weight, or a more distinctive setting design.
Strategy 5: Consider Lab-Grown Diamonds For Higher Clarity At Lower Cost
Lab-grown diamonds are produced under controlled conditions that typically result in fewer and less severe inclusions than natural diamonds. As a result, lab-grown diamonds often come with higher clarity grades at significantly lower prices. A lab-grown VS1 or VVS2 diamond can cost 50 to 70 per cent less than its natural equivalent, making higher clarity grades genuinely accessible without a significant budget stretch.
How Carat Weight Changes Your Clarity Decision
This is an important nuance that many guides overlook: the same clarity grade looks different at different carat weights. As carat weight increases, the facets of the diamond grow larger, and inclusions become more visible both under magnification and, in some cases, to the naked eye.
| Carat Weight | SI1 Likely Eye-Clean? | Our Clarity Recommendation |
|---|---|---|
| Under 0.70 ct | Very likely | SI1 is often an excellent value at this size |
| 0.70 – 1.00 ct | Usually verify first | SI1 with verification, or VS2 for certainty |
| 1.00 – 1.50 ct | Sometimes verify carefully | VS2 recommended; SI1 only if verified eye-clean |
| 1.50 ct and above | Less reliably | VS2 minimum; VS1 preferred for step cuts |
| 2.00 ct and above | Rarely for SI grades | VS1 recommended; VS2 acceptable in brilliant cuts only |
In short: the larger the diamond, the more conservative you should be with clarity. An SI1 that is perfectly eye-clean at 0.85 ct may have its inclusions become more apparent in a 1.80 ct stone of the same grade.
Find Your Eye-Clean Diamond
The smartest clarity decision is not the highest grade it is the grade where your diamond looks flawless in the real world. For most buyers, that is VS2 or a carefully chosen SI1, and the saving over VVS or Flawless grades is substantial.
At Rings of UK, every diamond in our collection has been assessed for eye-cleanliness as well as certification grade. Our team in Hatton Garden can walk you through face-up comparisons, inclusion positions, and which specific stones represent the best balance of clarity and value for your budget.
Frequently Asked Questions About Diamond Clarity
What clarity grade should I buy for an engagement ring?
For most buyers, VS2 is the recommendation that balances quality and value most effectively. VS2 diamonds are reliably eye-clean, well-regarded on paper, and meaningfully less expensive than VVS grades above. If budget allows more flexibility, VS1 is an excellent choice. If budget is tighter, a verified eye-clean SI1 in a brilliant-cut shape can be outstanding value. Avoid I-grade diamonds for centre stones.
What does eye-clean mean and why does it matter?
Eye-clean means a diamond has no inclusions visible to the naked eye under normal viewing conditions at arm’s length in everyday light. It matters because clarity grading is done under 10x magnification, which reveals characteristics that are completely invisible in wear. An eye-clean SI1 looks identical to a VS1 or VVS2 on the hand, but can cost significantly less. Buying eye-clean rather than chasing a grade number is how savvy buyers get more for their budget.
Is VS1 or VS2 better?
Both VS1 and VS2 are excellent clarity grades with inclusions that are not visible to the naked eye. VS1 inclusions are slightly harder to find under magnification and tend to be smaller or fewer. In practical terms what you see wearing the ring VS1 and VS2 are indistinguishable. VS2 offers the same visible quality for less money, which is why it is our most commonly recommended clarity grade.
Can you see SI1 inclusions with the naked eye?
It depends on the specific stone. Many SI1 diamonds are completely eye-clean inclusions are easy to find under a loupe but invisible without one. Others have inclusions in positions or of a nature that makes them visible face-up. This variability is why you should never buy an SI1 without verifying its eye-clean status for the specific stone, either in person, via face-up video, or through a direct conversation with a knowledgeable jeweller.
Does clarity affect sparkle?
In the VS2 to SI1 range, clarity has no meaningful effect on sparkle. Cut quality is the primary determinant of brilliance. However, at I1 and below, large or numerous inclusions can interrupt the path of light through the diamond, reducing its light return and therefore its sparkle. This is one of the reasons I-grade diamonds are not recommended for engagement ring centre stones.
Why do emerald cut diamonds need higher clarity?
Emerald cuts are step-cut stones their facets are arranged in parallel rows that act like mirrors, giving you a transparent view into the interior of the diamond. Unlike brilliant-cut shapes that scatter light and mask inclusions, the emerald cut puts the inside of the stone on full display. An inclusion that would be invisible in a round SI1 can be clearly apparent in an emerald SI1. For emerald cuts, VS2 is the minimum recommended grade, with VS1 preferred for stones over 1.25 ct.
Do lab-grown diamonds have better clarity?
Lab-grown diamonds are produced under controlled conditions and frequently achieve higher clarity grades than comparable natural diamonds. VVS and VS clarity grades are more common in lab-grown stones at a given price point, making higher clarity more accessible for buyers on a set budget. All lab-grown diamonds at Rings of UK are certified by GIA or IGI and graded on the same clarity scale as natural diamonds.
What is the difference between an inclusion and a blemish?
An inclusion is an internal characteristic a crystal, feather, cloud, or pinpoint within the body of the diamond. A blemish is a surface characteristic a scratch, pit, or abrasion on the outer surface of the stone. Both are assessed in the clarity grade, but inclusions typically have more impact on the grade because they are inside the stone and cannot be polished away. Most blemishes on a well-maintained diamond are minor and do not affect its beauty.
Should I buy a higher clarity grade for a larger diamond?
Yes. As carat weight increases, the facets of the diamond grow larger and inclusions can become more visible. An SI1 that is perfectly eye-clean at 0.80 ct may show its inclusions more readily at 1.50 ct. For diamonds above 1.25 ct, we recommend starting at VS2 and only considering SI1 if you have been able to verify the specific stone is eye-clean face-up. For step-cut shapes above 1.50 ct, VS1 is a more comfortable choice.
