On diamond clarity: what inclusions are, which matter, and which are irrelevant

Diamond clarity describes the presence of internal characteristics — inclusions — and surface characteristics — blemishes — within or on the stone. The GIA clarity scale runs from FL (Flawless) through IF, VVS1, VVS2, VS1, VS2, SI1, SI2, I1, I2, I3. Understanding which of these grades actually matter for a ring worn on a hand requires setting aside the academic scale and asking a more practical question: at what point does an inclusion affect the stone’s beauty under normal conditions?

Eye-clean: the correct standard

The standard I apply when sourcing stones for clients is eye-clean: is this inclusion visible to the naked eye, from a normal viewing distance of approximately 25–30cm, without magnification?

This is the only standard that matters for an engagement ring. You are not going to be inspecting your partner’s ring under a loupe every morning. Neither is anyone else. An inclusion that requires a 10x magnifying glass to find does not affect the beauty of the ring in daily life. An inclusion that is visible without magnification does.

Most VS1 and VS2 diamonds are reliably eye-clean. Many SI1 diamonds are eye-clean, particularly in round brilliants where the cutting style’s numerous small facets scatter light effectively and mask inclusions. SI1 in an emerald cut is a different matter — the step-cut’s large, mirror-like facets expose inclusions clearly — and I would not use an SI1 emerald cut in a Rauno Oidram ring regardless of price.

What different clarity grades mean in practice

FL and IF (Flawless / Internally Flawless): genuinely remarkable stones, commanding significant premiums. No practical difference from VVS1 in a set ring. The premium reflects rarity and collector interest, not visible quality improvement.

VVS1 and VVS2 (Very Very Slightly Included): inclusions visible only under 10x magnification to a trained eye. Reliably clean in any setting style. The step down from FL in price without visual compromise.

VS1 and VS2 (Very Slightly Included): inclusions visible under 10x magnification. Almost always eye-clean. The target range for most of my commissions — good value against the VVS range without any visual compromise.

SI1 (Slightly Included, grade 1): inclusions visible under magnification, sometimes visible to a careful naked eye. Evaluate each stone individually. In rounds and ovals, often eye-clean. In emerald cuts and Asscherts, often not. I assess every SI1 stone I propose before recommending it.

SI2 and below: generally not suitable for a principal stone in a ring at this level. The inclusions are reliably visible, and the price difference does not compensate for the visible quality compromise.

The shape-clarity interaction

Different shapes tolerate different clarity ranges because of how they handle light. Brilliant cuts — round, oval, cushion, pear — use numerous small facets that scatter light and minimise the visibility of inclusions. Step cuts — emerald, Asscher, baguette — use large, open facets that act like mirrors, exposing anything within the stone to view.

As a result, I source step-cut stones in VS1 or higher as a matter of course. For brilliant cuts, VS2 and SI1 can both work depending on inclusion type and position. An inclusion in the corner of the stone, below where a claw will sit, is effectively invisible in the finished ring. An inclusion dead-centre in the table is visible regardless of clarity grade.

What I do not recommend spending money on

FL and IF diamonds are beautiful objects. They are also, for a ring that will be worn daily, a premium spent on a distinction that is only relevant in a laboratory. I have sourced FL stones for clients who specifically wanted them. I have also told clients that the VS1 alternative at 40% less represents identical value in daily life. The choice is theirs; the information is mine to provide.

For how clarity interacts with cut in different stone shapes, see How to choose a stone shape that flatters the hand it will live on. For full diamond quality guidance, read On diamond cut and On diamond colour.