Diamond Clarity Guide: direct answer
Clarity describes the internal features and surface characteristics of a diamond — how many there are, how large, where they sit, and how readily they are seen. It is graded at 10x magnification, which is the single most important fact about it: the entire scale is defined by what a trained grader sees through a loupe, not by what you see on a hand.
That gives buyers a straightforward rule. The threshold that matters is eye-clean — no inclusions visible to the unaided eye at normal viewing distance. Above that point you are paying for grades nobody can see without equipment. Clarity is therefore usually the easiest characteristic to economise on, and the money is far better spent on cut.
The complication is that eye-clean is not a grade. It depends on the stone’s size, its shape, and crucially where the inclusions sit — which is why the plotted diagram on the report matters more than the letter.
What this term or grading factor means
Internal features are called inclusions; surface features are called blemishes. Most inclusions are natural crystals, feathers or clouds formed while the diamond grew, and they are effectively the stone’s fingerprint — no two are identical.
| Grade | Meaning at 10x | Practical appearance |
| FL / IF | Flawless or internally flawless | Eye-clean; rare and priced at the top |
| VVS1 / VVS2 | Very very slightly included; difficult even for a grader to find | Eye-clean in every practical case |
| VS1 / VS2 | Very slightly included; minor and not easily seen at 10x | Eye-clean; the usual value sweet spot |
| SI1 / SI2 | Slightly included; noticeable at 10x | Often eye-clean, but must be checked individually |
| I1 / I2 / I3 | Included; obvious at 10x | Usually visible to the eye; may affect durability |
The band where judgement is genuinely required is SI. An SI1 stone with a small inclusion near the girdle can be perfectly eye-clean and excellent value; an SI1 with a dark crystal directly under the table can be visible and is not worth buying. Same grade, entirely different stones.
How it is assessed or identified: 4Cs, certification, design suitability, price factors and the buyer’s next decision
Clarity is assessed by trained graders under 10x magnification in controlled lighting, following the method set out in GIA’s grading methodology. The grade reflects five things: the size of the inclusions, their number, their position, their nature, and how visible they are against the stone.
Position is the factor buyers can actually exploit. A report includes a plotted diagram mapping where each inclusion sits, and that diagram is the most useful thing on the page.
- Under the table — the flat top facet. The worst position, directly in the line of sight.
- Near the girdle or under a crown facet — much less visible, and often coverable by a prong when the stone is set.
- In the pavilion — can reflect through the stone and appear multiplied, so worth asking about.
This is why buying a loose stone and building the mount around it is genuinely valuable: a setter working from the plot can position a prong over a specific inclusion, so you buy a lower grade and see no difference. See loose diamonds South Africa. As with every characteristic, laboratories differ in strictness — check which one issued the report and verify the number on its own database. See diamond certificate explained.
What buyers should look for
Ask one question of every stone: is it eye-clean at normal viewing distance? Then verify it yourself rather than taking the answer on trust. Where the threshold falls depends on three things.
- Size. Larger stones have larger tables and show inclusions more readily. A grade that is comfortably eye-clean at one carat may not be at three, so raise the threshold as the stone grows.
- Shape and faceting. Brilliant-faceted shapes — round, oval, cushion, pear — break up light and genuinely disguise small inclusions. Step cuts such as emerald and Asscher have large open facets like windows into the stone, and hide nothing. A step cut needs a higher clarity grade than a round of the same size, and this is one of the most consequential facts in diamond buying. See diamond shapes.
- The nature of the inclusion. A white or transparent crystal is far less noticeable than a dark one. A feather near the surface is worth asking about for durability reasons, not just appearance.
One durability note: most inclusions have no effect on how well a diamond survives wear. The exception is a large feather reaching the surface, particularly near the girdle, which can create a weak point. Ask specifically about this on heavily included stones.
How it affects appearance, quality or price
Clarity affects price substantially and appearance comparatively little, which is exactly why it is the best place to save. The premium at the top of the scale is real money for differences invisible without a loupe.
The strategy that follows is straightforward: find the lowest grade that is genuinely eye-clean for that specific stone in that specific shape at that specific size, buy it, and put the difference into cut. Cut is what produces brightness and sparkle, and it is the only characteristic visible from across a room. A VS or well-chosen SI stone with an excellent cut will consistently outperform a flawless stone cut poorly, and cost considerably less.
Two related notes. Clarity treatments exist — fracture filling and laser drilling can improve apparent clarity, and both must be disclosed on the report. A treated stone should not be priced as an untreated one. And in multi-stone designs such as eternity bands and halos, clarity is close to irrelevant at those stone sizes; consistency of colour matters far more.
Common misunderstandings and mistakes
- “Flawless is the goal.” It is the most expensive option and looks identical to several grades below it on a hand. Very few buyers get value from it.
- “Inclusions are flaws or damage.” They are natural features formed as the crystal grew, and they are what makes each stone individual. They are not defects.
- “SI means poor quality.” Many SI stones are entirely eye-clean and represent the best value on the scale. It depends on the individual stone, which is why you look at the plot.
- “The grade tells me how it looks.” It tells you what a grader saw at 10x. Two stones of the same grade can look completely different depending on inclusion position.
- “Clarity affects sparkle.” Cut affects sparkle. Clarity affects sparkle only in heavily included stones where inclusions genuinely impede light.
- “I should choose a grade before choosing a shape.” The other way round — the shape determines what grade you need.
What to do next before buying
Choose the shape first, since it sets the clarity requirement. Then ask for the plotted diagram of any stone you are considering and look at where the inclusions sit, not just the letter on the report. View the stone face-up at arm’s length in normal light before anyone shows it to you under a loupe — that is the test that matters. And if the mount has not been made yet, ask whether a prong can be positioned over an inclusion, because that turns a cheaper grade into a free saving.
Continue with the other characteristics at diamond colour guide and diamond cut guide, or see all four at diamond 4Cs explained. For the whole process, the diamond buying guide.
Continue to the relevant buying guide or book expert guidance
Tell us the shape and size you want and we will show you eye-clean stones at the lowest grade that genuinely works for them, with the plotted diagrams, so you can see exactly what you are not paying for.