VS2 and SI1 are neighbours on the clarity scale, but they sit on either side of a useful line: almost every VS2 is clean to the naked eye, while an SI1 has to be judged stone by stone. It is the comparison where a careful buyer can save the most without seeing any difference, and where a hurried one can end up with a visible mark. We show both grades on real stones from our certified loose diamonds in Beirut and our 1 carat diamonds, each graded by GIA or HRD and filmed in 360°.
What the two grades mean
At 10× magnification, VS2 inclusions are minor and take some effort to find, while SI1 inclusions are noticeable to a trained grader. GIA and HRD both use these two grades and judge them the same way. Neither grade tells you whether you will see anything without a loupe: that depends on what the inclusions are and where they sit.
| VS2 | SI1 | |
|---|---|---|
| Full name | Very slightly included, second grade | Slightly included, first grade |
| At 10× | Minor inclusions, found with some effort | Inclusions noticeable to a trained grader |
| Typical features | Small crystals, pinpoints, fine feathers, light clouds | Larger crystals or feathers, clusters, clouds |
| To the naked eye | Clean in almost every brilliant shape | Often clean, especially under about one carat |
| What to check | A quick look at the video | The plot, the comments line and the video, closely |
Two SI1 stones can look nothing alike. A white feather near the girdle can be invisible, while a dark crystal under the table catches the eye at once. Clouds deserve a second look too: a heavy one can soften the brilliance without any single spot showing, and a GIA comments line such as “clouds are not shown” means some of them are missing from the plot. Our colour and clarity chart places both grades on the full scale, and our guide on how to read a GIA report shows where the plot and comments sit.
See the difference on real stones
Here is one stone of each grade from our Beirut stock with its 360° video and full grades; they may differ in size or colour, so watch how hard the inclusions are to find as each stone turns.
When to choose VS2
Choose VS2 when you want eye-clean to be as close to a certainty as the scale allows.
- You are choosing from a distance. Buying from abroad or as a surprise, a grade that needs little interpretation is worth a great deal.
- The stone is large or a step cut. Above about 1.5 carats, or in an emerald or asscher cut, an SI1 is much less likely to stay hidden.
- You would rather not study plots. VS2 leaves a comfortable margin, so the video confirms the choice rather than decides it.
When to choose SI1
Choose SI1 when you are willing to judge the actual stone, because that is where the value lies. In a well-cut round, oval or cushion under about one carat, a good SI1 looks identical to a VS2 on the hand, and the saving can go into a better cut, a whiter colour or a little more size. A good SI1 passes three tests:
- Its inclusions are white or transparent, not black.
- They sit towards the edge, ideally where a prong will cover them, rather than under the table.
- The stone looks bright and crisp on video, with no haze from clouds.
If an SI1 fails any of the three, step up to VS2 rather than hoping it will not show.
How shape, size and setting change the answer
Shape
Brilliant cuts hide; step cuts reveal. An SI1 can be a fine choice in a round brilliant, oval, cushion, radiant or princess cut, but in an emerald cut we would stay at VS2 or above.
Size
Size works against SI1. A half-carat SI1 is very often eye-clean; at two carats the same grade usually means larger features under a wider table. Above about 1.5 carats, treat an eye-clean SI1 as a find to confirm on video, not an assumption.
Setting
Prongs at the edge can hide a girdle inclusion, a bezel covers the rim entirely and a halo pulls the eye outward. A slim solitaire shows more of the stone than any other setting. Our guide to eye-clean diamonds explains how inclusion type and position decide what anyone sees.
How we would choose
If you want certainty, buy VS2. If you want value and are ready to look closely, a carefully chosen SI1 is the smartest grade on the scale. For the step above, see our comparison of VS1 and VS2 clarity. Tell us on WhatsApp which way you lean and we will send the certificate and 360° video of each stone that fits, with a plain note on where its inclusions sit.
Common questions
Is SI1 clarity good enough for an engagement ring?
Often, yes, but stone by stone. An SI1 with small, light inclusions near the edge can be perfectly eye-clean in a brilliant cut, especially under about one carat. One with a dark inclusion under the table is not. The certificate gives the grade; the 360° video of the actual stone tells you which kind you are looking at.
Can you see the difference between VS2 and SI1?
Not in a good SI1 seen at a normal distance. The difference shows under a loupe, or in an SI1 whose inclusions are dark, central or large for the stone. In step cuts and stones above about 1.5 carats the gap widens, which is why we suggest VS2 there.
Does SI1 clarity affect sparkle?
Usually not. Most SI1 inclusions are too small to change how light moves through the stone. The exception is a heavy cloud, which can make a diamond look slightly soft or hazy. That shows on a good video, so look for crisp contrast between light and dark facets as the stone turns.
Is an SI1 eye-clean in a 1 carat diamond?
Often, in a well-cut round or oval, but not always. At one carat a round measures about 6.4 millimetres across, large enough for a central crystal to catch a sharp eye. Read the plot, check where the inclusions sit and confirm on video before you choose an SI1 at this size.
What is the difference between SI1 and SI2?
SI2 inclusions are easier to find at 10× and more often visible to a sharp eye, especially in larger stones or from the side. Some SI2 diamonds are still eye-clean, but they have to be found one at a time, so an SI2 should only be bought after a close look at the actual stone.