As a diamond crystallizes, it traps tiny internal features called inclusions. This happens whether the diamond is grown in a lab over a few weeks or formed naturally over billions of years - the underlying physics is the same. Some inclusions are mineral crystals, some are gas pockets, some are stress fractures.

A clarity grade tells you how big, how many, where, and how visible those features are. It does not tell you whether you’ll see them in a ring.

The single phrase you need is eye-clean - a stone whose inclusions are noted on the certificate, can be seen by a gemologist under 10× magnification, but are invisible when you look at the ring on a hand.

Clarity is graded on an 11-grade scale, from Flawless (FL) at the top to Included (I3) at the bottom. Here is what each tier means, and when it makes sense to choose it.

FL - Flawless: No inclusions or blemishes under 10× magnification. The rarest grade, and priced to match - usually chosen for collecting rather than for how it looks on the hand.

IF - Internally Flawless: No inclusions inside the diamond; only tiny surface marks a gemologist can find at 10×. Looks identical to Flawless once it is set in a ring.

VVS1 / VVS2 - Very, Very Slightly Included: Inclusions so small they are hard for a gemologist to find even under magnification. A good choice if you want the reassurance of a near-perfect grade.

VS1 / VS2 - Very Slightly Included: Minor inclusions, difficult to see at 10× and almost always invisible to the naked eye. A popular balance of clarity and price.

SI1 / SI2 - Slightly Included: Inclusions are visible under 10× and can sometimes be seen with the naked eye. Many SI1 diamonds are eye-clean; SI2 varies, so review the video. The best place to look for value, as long as you check each stone.

I1 / I2 / I3 - Included: Inclusions are easy to see with the naked eye and can affect durability. Rare Carat does not stock these grades.

When you’re shopping, two things matter more than the grade letter: location (anything under the table, dead-center, is more visible than anything near the girdle) and size (a single 1mm crystal beats a half-dozen pinpoints).

Inclusions sit inside the stone; blemishes sit on the surface. The clarity report (a “plot”) maps them out like a constellation on the diamond outline.

Crystals, pinpoints, clouds, feathers, needles - the common internal characteristics. Tiny ones are invisible to the eye even at SI clarity. A single big crystal under the table can be visible at VS2.

Naturals, polish lines, surface graining - common surface features. Almost never visible without a loupe.

Because location and size matter more than the grade letter, watch the 360° video before you buy. The certificate tells you what’s there; the video tells you whether it matters.

Round, Oval, Cushion, & Pear Cuts: SI1 with a clean 360° video. Eye-clean, with big savings compared to VS.

Emerald, Asscher, & Baguette Cuts: VS2 minimum - their long, open facets make any inclusion easier to spot.

Any diamond over 2 carats: VS2 or better, whatever the shape. A larger stone has a bigger face, so inclusions are easier to notice.

Clarity is the second-easiest C to compromise on after color - the gap between SI1 (eye-clean, ring-ready) and FL (museum piece) is mostly invisible to humans, and very visible on the price tag.