Diamond Clarity Grades Explained: A UK Buyer's Guide

Diamond clarity describes how clean a diamond looks under 10x magnification. The official scale runs from Flawless (FL) at the top to Included (I3) at the bottom, with VVS1, VVS2, VS1, VS2, SI1 and SI2 sitting in the middle range that almost every UK engagement ring buyer will actually consider. For most rings, the right answer is the lowest clarity grade where the diamond still looks completely clean to the naked eye — often VS2 or a well-chosen SI1 — because that is where appearance and value meet.

This guide explains what each grade really means, what you will and will not see in the stone, and how to choose clarity confidently for a bespoke diamond engagement ring.

What "clarity" actually means

Every natural diamond formed under heat and pressure deep in the earth, and almost all of them carry tiny internal features called inclusions (inside the stone) and external features called blemishes (on the surface). Lab-grown diamonds carry their own version of these too.

Clarity grading judges:

• how many of these features are present
• how large they are
• where they sit in the stone
• how visible they are under 10x magnification
• how much they affect brilliance

Independent laboratories — most notably the GIA and IGI — grade clarity to a published, internationally recognised standard. A clarity grade on a real lab certificate is the only version worth trusting.

The diamond clarity scale, in plain English

The full GIA/IGI scale has eleven grades. In a UK engagement ring context, only the middle band really matters.

FL — Flawless. No inclusions or blemishes visible at 10x. Extremely rare. Priced as a collector grade.

IF — Internally Flawless. No internal inclusions; only minor surface marks. Visually indistinguishable from FL once set.

VVS1 / VVS2 — Very, Very Slightly Included. Inclusions are tiny and very difficult to see even under 10x. Completely eye-clean. A safe, premium choice with a price step up from VS.

VS1 / VS2 — Very Slightly Included. Inclusions are minor and usually not visible to the naked eye. This is the sweet-spot range for most engagement rings. VS1 is reliably clean; VS2 can be just as clean visually but is the grade where the buyer benefits most from a careful stone selection.

SI1 / SI2 — Slightly Included. Inclusions are noticeable under 10x and sometimes visible to the naked eye depending on the stone. A well-chosen SI1 — especially in a round brilliant — can look indistinguishable from a VS2 at a lower price. SI2 is more of a gamble and should never be bought sight-unseen.

I1 / I2 / I3 — Included. Inclusions are obvious to the naked eye and can affect durability and sparkle. Not recommended for an engagement ring you intend to keep for life.

The grade you actually want: "eye-clean"

The phrase you will hear most often from a good jeweller is eye-clean. This is not a formal grade; it is a practical test. An eye-clean diamond is one where, held at a normal viewing distance under normal light, you cannot see any inclusions with the naked eye.

For an engagement ring, eye-clean is almost always the real target. Once a diamond is eye-clean, paying for a higher clarity grade rarely changes how the ring looks — it changes the certificate.

That is why, for a typical solitaire or halo engagement ring, the smart range is:

• VS1 — reliably eye-clean across all shapes
• VS2 — eye-clean in most stones, especially when chosen carefully
• SI1 — eye-clean in many stones, especially in brilliant cuts where facets help hide inclusions

A bespoke jeweller's job is to pick the specific stone within the grade that gives you a clean face-up appearance for the lowest sensible spend.

How clarity interacts with shape

Different diamond shapes hide or reveal inclusions differently. This matters more than most buyers realise.

Round brilliant. The most forgiving shape. Its 57–58 facets break up light and disguise small inclusions, which is why SI1 round brilliants can still look perfectly clean.

Oval, pear, marquise, heart, cushion. Still brilliant-cut and reasonably forgiving, but elongated shapes show centre-of-stone inclusions more easily.

Emerald and Asscher (step cuts). The least forgiving. Long, open facets act like a window into the stone, so even small inclusions can be visible. For a step cut, push clarity to at least VS2 and ideally VS1.

Princess, radiant. Mixed-cut; usually forgiving but check for inclusions near the corners, which are also the most vulnerable points.

If you are considering an emerald cut, our companion piece — Emerald Cut Diamond Engagement Rings: a UK Buyer's Guide — explains why clarity matters so much in step cuts.

Why this matters for buyers

Clarity drives a meaningful share of a diamond's price. Moving up one grade — say from SI1 to VS2, or from VS2 to VS1 — can add 10% to 25% to the diamond cost, depending on shape and size. Across the full scale, the difference between an SI1 and a VVS1 in the same colour, cut and carat can be 60% or more.

That is a lot of money to spend on something that, if both stones are eye-clean, will look the same on her finger.

A practical UK buyer's mindset:

• Set a clarity floor, not a clarity target. Decide the minimum grade you are comfortable with (often VS2 or SI1), then optimise the rest of the diamond.
• Prioritise cut over clarity. Cut quality drives how the diamond sparkles. A poorly-cut VVS1 can look duller than a beautifully-cut VS2.
• Use the budget you save to go up in carat or cut quality — both of which you will see, every day.

This is the same logic we walk buyers through in our guide to how much to spend on an engagement ring in the UK.

How Diamond Hub approaches clarity

Clarity is one of the most rewarding parts of a bespoke consultation, because it is where buyers usually save the most money without giving anything up visually.

When you commission a ring through our bespoke engagement ring service, the process around clarity looks like this:

1. We start from your shape, carat range and metal — the variables you will actually see.
2. We then identify the lowest clarity grade that reliably looks eye-clean in that combination.
3. We hand-select specific stones within that grade, looking at the position and type of any inclusions on the certificate plot.
4. We rule out any stones where the inclusion sits in a visible position, near the table, or anywhere structurally weak.
5. We present a shortlist of stones, with their full lab reports, so you can compare like-for-like.

The result: a ring that looks clean and brilliant face-up, with a certificate that backs it up, at a price that reflects real visual quality rather than a number on paper.

You can see this approach across our engagement ring collection, where most of our hero stones sit in the VS1–SI1 range and have been individually selected for face-up appearance.

What to consider before choosing clarity

A short, practical checklist before you commit:

• What shape have you chosen? Step cuts need higher clarity; brilliant cuts can go lower.
• What carat are you aiming for? Larger stones (over 1.5ct) show inclusions more easily, so push clarity up a step.
• Is the diamond certified by GIA or IGI? A grade is only as reliable as the lab behind it.
• Have you seen the certificate plot? A small inclusion on the edge under a claw is invisible; the same inclusion under the table is not.
• Is the diamond confirmed eye-clean by the jeweller? Ask the question directly.
• Are you comparing like-for-like? Two SI1 diamonds can look very different. Always compare specific stones, not just grades.

If you are also still deciding between certified lab-grown and natural stones, our lab-grown vs natural diamonds UK buyer's guide covers how clarity behaves in each.

FAQ

What is the best clarity for an engagement ring? For most engagement rings, VS1, VS2 or a carefully chosen SI1 offers the best balance. All three are usually eye-clean, and the saving versus VVS grades can be reinvested in cut quality or carat weight.

What does "eye-clean" mean? Eye-clean means the diamond shows no visible inclusions to the naked eye at normal viewing distance. It is the practical standard most UK buyers should aim for, regardless of formal grade.

Is SI1 clarity good enough for an engagement ring? Often yes, especially in a round brilliant or other brilliant-cut shape. A hand-selected SI1 can look identical to a VS2 in the finger. SI1 is riskier in step cuts like emerald or Asscher.

What is the difference between VS1 and VS2? Both are "Very Slightly Included." VS1 inclusions are smaller and harder to see under 10x; VS2 inclusions are slightly larger but still typically invisible to the naked eye. VS1 is the safer choice if you want a guaranteed clean look without paying for VVS.

Do lab-grown diamonds have clarity grades? Yes. Lab-grown diamonds are graded on the same clarity scale as natural diamonds by labs such as IGI and GIA, and they carry the same range of inclusions.

Will inclusions affect how durable the diamond is? Usually no. Most inclusions are cosmetic. The exception is when a large inclusion sits near the girdle or at a stress point — a good bespoke jeweller will flag this and rule the stone out.

Should I buy a diamond without seeing it first? Not without expert verification. Two stones with the same clarity grade can look very different. Either view the stone in person, or buy through a jeweller who hand-inspects each stone on your behalf and shows you the certificate.

A confident clarity choice, every time

Clarity rewards buyers who understand it. Once you know that eye-clean is the real target, that shape changes the answer, and that the certificate alone does not tell the whole story, you can spend confidently in the grade range that gives you the best ring for your budget.

If you would like a specific stone hand-selected for clean face-up appearance — and a ring built around it — our team can guide you through every choice. Start a conversation through our bespoke engagement ring service or browse the current engagement ring collection for inspiration.