What Is the Best Clarity for a Lab-Grown Diamond?

The Clarity Scale, Explained

Clarity measures how many inclusions (internal characteristics) and blemishes (surface characteristics) a diamond has, and how easily a trained grader can see them under 10x magnification. IGI and GIA both grade lab-grown diamonds on the same 11-point scale used for mined stones, running from Flawless down through Internally Flawless, Very Very Slightly Included, Very Slightly Included, Slightly Included, and finally Included.

Inclusions form during crystal growth. In a mined diamond that happens underground over millions of years; in a lab-grown diamond it happens inside a growth chamber over a matter of weeks. Either way, the resulting internal characteristics look the same to a grader, because a lab-grown diamond is chemically, physically, and optically identical to a mined one  the clarity scale doesn't distinguish between the two origins, only the diamond in front of the grader.

Graders are actually looking for specific characteristics with names of their own: feathers (small internal fractures), pinpoints (tiny mineral crystals), clouds (clusters of pinpoints that can soften brilliance if dense enough), needles, and internal graining, alongside surface blemishes like naturals, extra facets, or polish lines left from cutting. The number, size, relief (how much they stand out against the surrounding diamond), and position of these characteristics all factor into the final grade not just how many there are.

Position matters more than most buyers expect. An inclusion sitting directly under the table (the flat top facet) is far more visible than the same inclusion tucked near the girdle edge, where the mounting and side facets naturally hide it. This is part of why two diamonds with the same clarity grade can still look different in person, and why an IGI plotting diagram which maps exactly where each characteristic sits is worth a look before buying, not just the letter grade on its own.

Clarity Grades Compared

Here's how each grade actually behaves once the diamond is set in a ring, rather than sitting under a jeweler's loupe:

In practice, the gap that matters most is between SI2 and VS2. That's usually where "might see something without trying" turns into "won't see anything without a loupe," which is the line most buyers actually care about. The gap between VS1 and FL, by contrast, is almost entirely a paper distinction — both look identically clean to the eye, and the price difference between them buys documentation, not appearance.

Not all inclusions affect visibility equally, either. A white or colorless inclusion of a given size is generally less noticeable than a dark or black inclusion of the same size, since dark inclusions absorb light instead of blending into the surrounding brilliance. This is why two SI1 diamonds can look different in person even though they carry the identical grade on paper.

Best Clarity by Diamond Shape

Clarity doesn't work in isolation. The way a shape's facets are cut changes how much light bounces around inside the stone, which either hides or exposes whatever sits below the surface:

• Round brilliant: 58 facets scatter light in a pattern that hides small inclusions well, which is part of why round is considered the most forgiving shape. SI1 often looks eye-clean, and even some SI2 stones pass at a glance.
• Cushion and princess: Similarly forgiving thanks to their brilliant-style faceting, though princess cuts can show inclusions near the pointed corners more readily. VS2-SI1 is usually enough to stay eye-clean.
• Oval, pear, and marquise: The elongated "bowtie" shadow across the center of these cuts can draw the eye straight to any inclusion sitting there, since the bowtie area already has the least light return in the stone. Aim for VS1-VS2 to keep that zone clean.
• Emerald and asscher (step cuts): Large, open, parallel facets act like a hall of mirrors, magnifying whatever sits inside the stone rather than scattering it. VS1 or higher is the safer floor for these shapes, many buyers of step cuts choose VVS specifically because of this effect.

As a rule of thumb: the more a cutting style relies on scattering light in many directions (brilliant cuts), the more forgiving it is of lower clarity. The more it relies on large, flat, mirror-like facets (step cuts), the higher the clarity needs to climb to stay eye-clean.

IGI Grading for Lab-Grown Diamonds

The International Gemological Institute (IGI) is the most widely used lab for grading lab-grown diamonds worldwide, alongside GIA. Both examine the same four characteristics cut, color, clarity, and carat weight and issue a certificate documenting the grade, along with a report number that can be verified independently.

An IGI report includes a plotted clarity diagram showing the type, size, and position of any inclusions, so you're not relying on a marketing description of "eye clean." The report number can be looked up directly on IGI's own verification tool, which confirms the certificate matches a real, graded stone rather than a generic or reused document. Every ring sold as certified should come with this documentation, not just a grade printed on the product page.

IGI and GIA are both internationally recognized and both trustworthy, though IGI has become the dominant lab specifically for lab-grown diamonds due to faster turnaround and wider global reach, while GIA's grading has a reputation for being marginally more conservative on borderline grades. In practice, buyers shouldn't need to choose between the two most reputable lab-grown jewelry, JewelCoves included, is sold with IGI certification as standard, and the grading criteria themselves don't change based on which lab issues the report.

Clarity and the Other 3 Cs

Clarity is one lever out of four. Cut has the biggest impact on how a diamond actually sparkles, followed by color, then clarity, with carat weight last for visual impact though obviously first for sheer size. A well-cut SI1 diamond will often out-sparkle a poorly-cut VVS2, because cut quality determines how efficiently light enters and exits the stone in the first place; clarity only determines whether anything is in the way once it gets there.

Because lab-grown diamonds typically cost 60-85% less than a mined diamond of the same specifications, most buyers don't have to trade clarity for carat, or color for cut, the way they would shopping for a mined stone on the same budget. It's usually possible to raise more than one of the 4Cs at once rather than picking a single priority and sacrificing the rest.

Consider two similarly priced 1.5-carat round diamonds: one graded I1 clarity with an excellent cut, and one graded VS2 with only a good cut. On paper, the VS2 stone looks like the clear win. In person, the I1 stone's visible dark inclusions can still dull its face-up brilliance more than the modest cut difference costs the VS2 stone which is exactly why "lowest clarity that's still eye-clean, then spend the rest on cut" tends to outperform "maximize clarity first" as a buying strategy.

Common Clarity Myths

A few assumptions about clarity are worth correcting before you shop:

Frequently Asked Questions

Final Thoughts

The best clarity for a lab-grown diamond isn't the highest one available, it's the lowest one that still looks flawless to the naked eye in your chosen shape. For most cuts, that lands on VS1 or VS2. For round and cushion shapes, SI1 can get you there for less. Either way, the certificate is what confirms it, not the listing copy, so check the plotting diagram before you check the price tag.