Diamond Clarity Explained: What the Grades Actually Mean
Diamond clarity is one of the 4Cs, but it's also the one that buyers most frequently over-invest in relative to what it contributes to a diamond's appearance. Understanding what the clarity grades actually measure — and what they don't — helps enormously in making a purchase that delivers real value rather than paying for characteristics invisible to the naked eye.
What Clarity Measures
Clarity refers to the presence of inclusions (internal characteristics, such as tiny crystals, feathers, or clouds) and blemishes (surface characteristics) in a diamond. These develop naturally during a diamond's formation under extreme heat and pressure deep within the earth, and virtually every diamond has at least some. The clarity grade reflects both the number and type of these characteristics and their visibility — primarily as assessed under 10x magnification by a trained grader.
The GIA Clarity Scale
The GIA (Gemological Institute of America) clarity scale runs from Flawless at the top to Included at the bottom, with several grades in between. Flawless (FL) and Internally Flawless (IF) diamonds have no inclusions or blemishes visible under 10x magnification — they are genuinely rare and command significant premiums. Very Very Slightly Included (VVS1 and VVS2) have inclusions so minute they are extremely difficult to see even under 10x magnification. Very Slightly Included (VS1 and VS2) have minor inclusions difficult to see under magnification. Slightly Included (SI1 and SI2) have noticeable inclusions under 10x magnification, though often not visible to the naked eye. Included (I1, I2, I3) have inclusions that affect transparency and brilliance, visible to the naked eye in at least some cases.
The Eye-Clean Concept
"Eye-clean" is one of the most useful practical ideas in diamond buying: a diamond is eye-clean if its inclusions are not visible to the naked eye under normal viewing conditions (that is, without magnification). An eye-clean diamond, regardless of what its laboratory grade says, appears clean and clear to the person looking at it — and for a ring worn on the hand rather than examined under a loupe, that is what actually matters.
Most VS1 and VS2 diamonds are eye-clean. A significant proportion of SI1 diamonds are eye-clean. Some SI2 diamonds are eye-clean, though it depends heavily on the nature and position of the inclusions. Whether an SI2 stone is eye-clean is something that genuinely has to be assessed stone by stone — the grade alone doesn't confirm it.
Where Most Buyers Find the Best Value
The VS1 to SI1 range is where most knowledgeable buyers find the best balance of quality and value. A VS1 or VS2 diamond will almost certainly be eye-clean, with inclusions well below the threshold of what can be seen without magnification, at a meaningfully lower price than VVS or Flawless grades that offer no visible improvement. SI1 diamonds often represent even better value, particularly when assessed individually to confirm eye-cleanliness.
Jumping to VVS or Flawless to "get the best" is generally a misallocation of budget unless the diamond is very large (above 3 carats or so, where inclusions can be easier to spot) or the buyer has a specific reason to prioritise these grades. The price premium for FL over VS2, in terms of visible appearance in a mounted ring, is rarely justified.
How Shape Affects Clarity Visibility
Diamond shape affects how visible inclusions are. Step cuts — emerald and Asscher cuts, with their large, open facets and parallel facet arrangement — show inclusions more readily than brilliant cuts. A VS1 or VS2 grade is generally recommended for step cut diamonds, where an SI1 might be eye-clean in a round brilliant. Brilliant cuts, with their many small facets creating a lot of light scattering and movement, are more forgiving of inclusions.
The Position of Inclusions Matters
Not all inclusions at the same clarity grade are equal. An inclusion under a prong or at the edge of the stone is effectively hidden; an inclusion in the centre of the table (the large flat facet on top) is the most visible position possible. Two SI1 diamonds can look very different depending on where and what type their inclusions are — another reason why assessing individual stones rather than relying on grade alone gives better results.
If you'd like guidance on finding an eye-clean stone at the right value point for your budget and chosen shape, book a consultation and we'll walk you through the options.