SI1 vs SI2 Diamond Clarity: Is SI Worth It?

SI1 is usually eye-clean. SI2 often isn't. Buy SI1 in a brilliant cut after checking the video, and treat SI2 as a stone you inspect before committing. But check the price first, on lab-grown, the saving that made SI clarity worth the risk has largely disappeared.

What does SI clarity mean?

SI stands for "slightly included." It sits below VS and above I on the clarity scale, and it means a grader found inclusions that are noticeable at 10x magnification.

Noticeable to a grader at 10x is not the same as visible to you. That's the whole question with an SI clarity diamond, and the grade on its own doesn't answer it.

One thing specific to lab-grown worth knowing up front: since October 1, 2025, GIA no longer assigns clarity grades to lab-grown diamonds. Its lab reports read Premium or Standard, and Standard requires VS clarity, so a stone at SI level gets no GIA assessment at all. In practice, an SI clarity diamond that's lab-grown will be IGI-graded. That isn't a downgrade; IGI grades the full scale and handles most of the world's supply.

SI1 vs SI2 side by side

The difference isn't a fixed amount of inclusion. It's a threshold a grader crosses, which is why two stones both graded SI2 can look completely different. Grading an SI clarity diamond is a judgment call, not a measurement.

What matters more than the number is where the inclusion sits. A feather near the girdle hides under a prong. A dark crystal under the table sits in the middle of your view, and no grade tells you which one you're getting.

Is SI clarity eye-clean by shape

Shape changes the answer more than the grade does.

• Round, oval, cushion, radiant, pear, marquise: Dense brilliant faceting scatters light and breaks up the view. SI1 is usually eye-clean here, and SI2 sometimes is.

• Princess: Brilliant faceting, but the corners show more. SI1 is workable, SI2 less so.

• Emerald, asscher: Step cuts with a wide open table and nothing to hide behind. Skip SI entirely. VS2 is the floor, and VS1 is better.

Size matters too while looking for clarity in lab grown diamonds. The larger the stone, the bigger the table and the more room an inclusion has to show. An SI clarity diamond that's invisible at 1 carat can be obvious at 3.

Our diamond clarity guide has the grade-by-grade breakdown, and the full clarity comparison covers how SI sits against VVS and VS.

When SI gets you a bigger diamond, and when it doesn't

This is where the standard advice has gone out of date.

The logic used to be simple, start with choosing an SI clarity diamond, save 15–25%, spend it on carat weight. That held when clarity was scarce. On lab-grown it frequently doesn't, because supply already clusters high on the scale.

Two pairs from our own stock, each matched on shape, carat and color:

Read the first pair: three clarity grades higher for just $11 more. In the second pair, the higher-clarity diamond actually costs $66 less.

So the honest answer to whether an SI clarity diamond is worth it: check the price before you accept the compromise. Where SI genuinely costs less, it's a sound way to buy more lab grown diamonds for the money. Where it doesn't, you're taking on inclusion risk for nothing.

Compare the two stones you're actually choosing between, not the two grades. The same applies when weighing a lab grown vs natural diamond, where the clarity premium behaves differently again.

It’s time to filter our lab grown diamond rings and loose stones by clarity and view every certificate before you buy. New here? See whether lab grown diamonds real, or browse our diamond jewelry.

FAQs about SI1 vs SI2 Diamond Clarity

Is SI2 eye-clean? 

Sometimes, not reliably. It depends entirely on where the inclusions sit and how busy the faceting is. Never buy SI2 without viewing the video, you can also call us in case of any doubt.

Is SI clarity good for lab-grown diamonds? 

It can be, but check the price first. Lab-grown supply sits high on the clarity scale, so SI often costs about the same as VS.

SI1 or VS2, which should I buy? 

Whichever is cheaper for the same shape, carat and color. If the gap is small, take VS2; the certainty is worth more than the savings.

Can a GIA report show SI clarity on a lab diamond? 

No. Since October 2025, GIA lab reports show Premium or Standard only, and Standard requires VS. SI stones get no assessment.

Does SI clarity affect sparkle? 

Barely. Cut controls sparkle. Clarity only dulls a stone when inclusions are large or cloudy enough to block light, which mostly means the I grades.

What inclusions should I avoid in an SI stone? 

Dark crystals under the table, clouds that soften the whole stone, and feathers reaching the surface. Pinpoints and girdle-edge feathers are fine.