Lab Grown Diamonds
Clarity Grades: What VS and SI Actually Look Like
The grade is set under magnification. What matters to you is where the inclusion sits, not what letter it earns.
Written by the Mapple Gems workshop, Surat Β· Updated 10 September 2026
Short answer
Clarity is graded at 10Γ magnification, so a grade describes what a loupe sees rather than what you will. VS1βVS2 is eye-clean in essentially every case; SI1 is usually eye-clean and often the best value in the scale; SI2 depends entirely on the stone. The variable that matters more than the grade is position β an inclusion under the table is far more visible than the same one near the girdle. Ask for the plot diagram, not just the letter.
Clarity is where the largest amount of money is spent on something invisible. The scale is real and well constructed, but it answers a question about magnified viewing, and buyers use it to answer a question about ordinary viewing.
The scale, in plain terms
| Grade | Under 10Γ | To the eye |
|---|---|---|
| FL / IF | Nothing internal visible | Clean β and so is everything below |
| VVS1 / VVS2 | Extremely hard for a grader to find | Clean |
| VS1 / VS2 | Minor, found with some effort | Clean |
| SI1 | Noticeable under a loupe | Usually clean β check position |
| SI2 | Easily seen under a loupe | Depends on the stone |
| I1 and below | Obvious | Visible; may affect durability |
Note where the money goes. The visual difference between IF and VS2 is nil at normal viewing, and the price difference is considerable.
Position beats grade, and the plot diagram is where you find it. Every full report includes a plot: a diagram of the stone with its inclusions mapped. Almost nobody looks at it, and it contains the information the letter cannot carry. An inclusion directly beneath the table β the large flat top facet β sits in the stoneβs clearest window with nothing to disguise it, so an SI1 there can be findable. The identical inclusion near the girdle is hidden by the setting, or masked by the busy flashing at the stoneβs edge, and is invisible. This is why two SI1 stones at the same price can be completely different purchases, and why asking for the plot is more useful than paying for a grade above it.
Size and shape change the answer
- Under 1Β ct: SI1 is comfortably eye-clean in a brilliant, and often SI2. Less material means a smaller, busier window for an inclusion to hide in.
- 1β3Β ct: VS2βSI1 is the sensible band.
- Above 3Β ct: move to VS1βVS2. A bigger stone gives the same inclusion a proportionally larger, calmer area to be seen in.
- Step cuts at any size: hold VS2 as a floor. Emerald and Asscher cuts have large open facets and no scatter to hide behind β they are the most revealing shapes there are.
What lab grown inclusions actually are
Different from mined stones, and worth knowing because it tells you something about origin.
HPHT stones can contain small metallic flux inclusions β traces of the metal catalyst used in growth. These are typically dark and, in rare larger cases, slightly magnetic. CVD stones tend toward non-metallic, graphitic inclusions and sometimes faint growth striations.
Neither is a quality problem at normal grades, and both are how laboratories identify how a stone was grown. What matters practically is the same as always: size, position, and whether it is visible without magnification.
Where clarity affects durability
Almost never, but there is one case worth naming. A large inclusion that reaches the surface at the girdle, or a feather running toward an edge, can be a structural weak point β a place where a sharp knock could start a chip.
This is essentially confined to I1 and below and is visible on the plot diagram. At VS and SI grades it is not a consideration. If a report shows a significant feather near the girdle on a stone you are considering, ask about it specifically.
How to buy clarity well
- Decide eye-clean is the goal, not maximal. Above eye-clean you are buying a line on a report.
- Ask for the plot diagram and look at where the inclusions sit relative to the table.
- Ask for video, rotating, in ordinary light. If you cannot find it in video, you will not find it on a hand.
- Take SI1 seriously as a value grade β with a good plot it is frequently the best purchase on the scale.
- Put the saving into cut, which is the only C that changes how a stone looks in ordinary light.
Keep reading
Frequently asked questions
What clarity grade is eye-clean?
VS1βVS2 in essentially every case, and SI1 usually β often making SI1 the best value on the scale. SI2 depends on the individual stone. Clarity is graded at 10Γ magnification, so the grade describes what a loupe sees rather than what you will at normal viewing distance.
Why can two SI1 diamonds look completely different?
Because position matters more than grade. An inclusion directly beneath the table sits in the stoneβs clearest window with nothing to disguise it, while the identical inclusion near the girdle is masked by the busy flashing at the edge or hidden by the setting. Ask for the plot diagram, which maps exactly where they sit.
Do emerald cuts need higher clarity?
Yes β hold VS2 as a floor at any size. Step cuts such as emerald and Asscher have large open facets and no scattered sparkle to hide behind, which makes them the most revealing shapes for inclusions. Brilliant cuts break light up constantly and disguise far more.
Can an inclusion affect a diamondβs durability?
Rarely, and essentially only at I1 and below β a large inclusion reaching the surface at the girdle, or a feather running toward an edge, can be a structural weak point. At VS and SI grades it is not a consideration. Anything of that kind appears on the plot diagram, so ask about it specifically if you see one.
Ask for the plot, not the letter.
It is on the report already, almost nobody opens it, and it is what decides whether a grade is a bargain or a compromise.
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