How to Find an Eye-Clean SI1 Lab Grown Diamond: 5 Tips From Diamond Experts

An eye-clean SI1 lab grown diamond is worth buying, but only if you pick the right stone. SI1 simply means inclusions are noticeable under 10x magnification; it says nothing about whether you can see them with your naked eye, and that distinction is the whole game. Roughly 70 to 85 percent of SI1 lab grown diamonds are eye-clean, depending on the shape and carat weight. The other 15 to 30 percent are not, and a certificate alone will not tell you which camp a specific stone falls into. These five tips will.

What does the IGI certificate’s Comments field actually tell you?

Read the Comments field before anything else on the report. It is the most commonly skipped section, yet it carries the most disqualifying information for SI1 buyers.

The phrase to watch for is “clarity grade based on clouds not shown.” When that line appears on an SI1 report, walk away. It means the stone’s grade is driven by a diffuse network of pinpoint inclusions spread through the body, too numerous for the gemologist to map individually. Those clouds tend to make the diamond look milky or hazy under normal light, even though no single inclusion shows up prominently on the plot diagram. The certificate looks almost clean. The diamond does not.

A separate phrase, “additional clouds not shown,” is far less alarming. It usually means tiny, scattered pinpoints that were too tedious to plot individually but are not driving the grade. That comment is generally fine at SI1.

For IGI-certified lab grown diamonds specifically, the Comments field also discloses the growth method (CVD or HPHT) and any post-growth color treatments. A stone that was color-treated after growth can carry resale implications worth knowing before you buy.

How do you read the IGI inclusion plot for SI1?

The inclusion plot on an IGI report is a top-down and bottom-up diagram of the stone with symbols marking the type and location of every mapped characteristic. Two things matter most: what kind of inclusion and where it sits.

On location: inclusions near the girdle edge are far safer than inclusions under the table facet. The table is the large flat top of the diamond, and anything sitting directly below it is the first thing your eye lands on when you look at the stone face-up. A small feather or crystal tucked near the edge can be invisible in a finished ring, sometimes hidden by a prong entirely.

On type: transparent or white inclusions are generally less visible than dark ones of the same size. IGI grades by size and number, not by color of the inclusion. So a small black carbon crystal under the table can be more eye-damaging than a larger white feather near the pavilion edge. Prefer stones where the primary inclusion listed is a pinpoint, feather, or transparent crystal sitting off-center.

For CVD lab grown diamonds specifically, watch for striations (also called internal graining): faint parallel lines caused by growth interruptions during the CVD process. Striations in SI1 CVD stones can appear as shadowy lines under direct light or when the stone is tilted. If the plot shows graining running through the table area, ask for a video before committing.

Does diamond shape change whether an SI1 is eye-clean?

Shape is probably the most underestimated variable in the SI1 decision. Brilliant-cut shapes scatter light across dozens of small facets, and that scintillation breaks up the eye’s ability to settle on an inclusion. Round brilliant, oval, cushion, pear, and radiant cuts all perform well at SI1 because the sparkle does the hiding for you.

Step cuts work the opposite way. Emerald and Asscher cuts have long, open parallel facets that act like windows into the stone rather than mirrors bouncing light in every direction. An inclusion that a round brilliant would mask completely can be clearly visible in an emerald cut of the same SI1 grade. If you are set on a step cut, consider moving up to VS2 rather than hunting for a rare eye-clean SI1.

The practical guide by shape:

• Round, oval, cushion, pear, radiant: SI1 is often eye-clean, especially under 1.5 carats.
• Emerald, Asscher, baguette: VS2 is the safer starting point.
• Princess, marquise: SI1 tends to work, but check the plot carefully for central inclusions.

Does carat weight affect how visible SI1 inclusions are?

Yes, and the effect is larger than most buyers expect. The same inclusion that registers as a barely-visible pinpoint in a 0.90-carat stone can become a noticeable flaw in a 2.00-carat version of the same clarity grade. Larger diamonds have bigger facets, which act as magnifying surfaces that make internal characteristics easier to resolve with the naked eye.

A practical threshold: for round brilliants under 1.5 carats, a well-selected SI1 is frequently eye-clean. Above 2 carats in any shape, the odds shift enough that VS2 becomes the more reliable choice if eye-cleanliness matters to you.

This is especially relevant for lab grown diamond buyers in 2026, because the price gap between lab and natural stones means buyers can often afford significantly larger carat weights than they could with mined diamonds. A bigger stone is a beautiful outcome, but it also means clarity selection requires more care, not less.

How do you verify eye-cleanliness before you buy online?

A certificate tells you what a gemologist saw at 10x magnification under controlled lighting. It does not tell you what you will see at arm’s length in an office or restaurant. Bridging that gap requires one more step.

Request a high-resolution video of the specific stone, ideally in face-up position under normal lighting rather than the intense spotlights used in most product photography. Many vendors, including Ouros Jewels, work with IGI-certified stones and can provide stone-specific images or videos before purchase. A stone that looks clean in a well-lit video at normal zoom is a strong candidate for being eye-clean in real life.

When viewing images, simulate normal viewing conditions: zoom out to roughly the size the stone would appear on a finger. Inclusions that look alarming at 40x on screen often vanish entirely at real-world scale. Conversely, a dark crystal under the table that is visible even at normal zoom is a red flag regardless of how the certificate reads.

If you are buying IGI Certified Round Lab Grown Diamond Stud Earrings or a loose diamond for a custom piece, the same rules apply: check the plot, confirm inclusion location, and ask for a video. The round brilliant shape in earrings is one of the most forgiving formats for SI1 clarity because face-up viewing at a distance hides minor inclusions even more effectively than in a ring.

SI1 Lab Grown Diamond: Worth It When You Pick Correctly

An eye-clean SI1 lab grown diamond is worth buying. The grade is not a risk; a poorly selected stone within that grade is. The decision comes down to one factor above all others: inclusion location. A small, transparent inclusion near the girdle in a round brilliant under 1.5 carats is almost always invisible to the naked eye. A dark crystal under the table of an emerald cut is almost always not.

Check the IGI Comments field first, read the inclusion plot for position and type, match the clarity grade to the shape, factor in carat weight, and verify with video. Do those five things and SI1 becomes one of the best value decisions in lab grown diamond buying. Eye-clean SI1 stones can save 15 to 25 percent compared to VS2 stones that look identical once set.

Frequently Asked Questions

Is an SI1 lab grown diamond always eye-clean?

No. Roughly 70 to 85 percent of SI1 lab grown diamonds are eye-clean depending on shape and carat weight, but the grade alone does not guarantee it. Each stone needs individual review: check the IGI inclusion plot for central inclusions, read the Comments field for cloud warnings, and request a face-up video before buying.

What is the biggest red flag on an SI1 IGI certificate?

The phrase “clarity grade based on clouds not shown” in the Comments section. It signals that the stone’s grade is driven by a diffuse cloud network not fully mapped on the plot. These diamonds frequently appear milky or hazy to the naked eye despite looking clean on paper, and no amount of cut quality will fix that.

Can I get an eye-clean SI1 in an emerald-cut lab grown diamond?

It is possible but much harder than in a brilliant cut. Emerald cuts have long, open facets that reveal inclusions a round brilliant would hide. For an emerald-cut lab grown diamond, most experts recommend starting at VS2 rather than SI1, unless you can view the specific stone and confirm no inclusions are visible face-up under normal light.

How much can I save by choosing SI1 over VS2 in a lab grown diamond?

Eye-clean SI1 lab grown diamonds typically cost 15 to 25 percent less than comparable VS2 stones of the same carat weight, color, and cut grade. On a 1.5-carat stone, that difference can represent several hundred dollars, money that can go toward a better cut grade, a larger stone, or a more detailed setting.

Does IGI grade lab grown diamonds differently for SI1 clarity than GIA?

IGI and GIA use the same 10x magnification standard and the same clarity scale. In recent years IGI has become noticeably stricter and more consistent than its earlier reputation suggested. For lab grown diamonds specifically, IGI has developed additional protocols to account for growth-method-specific inclusions like CVD striations and HPHT metallic flux, making its reports particularly detailed for lab stone buyers.