Diamond Fundamentals

Diamond Clarity

Learn about the diamond clarity grading scale, diamond inclusions and why a truly flawless diamond is so rare. In this guide, our experts advise which clarity grades to opt for, for an eye-clean diamond at the best price.

What is diamond clarity?

Diamond clarity measures the presence and severity of the internal marks, blemishes and flaws found in almost all diamonds. Whether natural or lab grown, it is incredibly rare to find a diamond totally free of such inclusions, but they do exist, and are known as ‘flawless diamonds’. The closer to flawless, the higher the diamond clarity, the rarer it is and greater the cost.

What determines a diamond clarity grade?

Mined diamonds form deep within the Earth over billions of years. Intense heat and pressure in the mantle encourage carbon molecules to crystallise and grow, picking up and trapping traces of other elements as they form. Small cracks and flaws within the diamond can form, also referred to as inclusions, or blemishes if on the surface of the stone. The severity of these marks are measured on a diamond clarity scale.

What causes inclusions?

The small marks and flaws found within diamonds are given the umbrella term ‘inclusions’, but there are many different types of diamond inclusions, caused by different phenomena. Some are more notable than others:

  • Crystal - a minuscule diamond (or other mineral) within the diamond; sometimes coloured
  • Pinpoints - tiny white or black crystals, appearing like a pinprick within the diamond
  • Needle - an elongated, thin line of crystal
  • Cavity or chip - usually caused by stressing a weak point during diamond cutting, a cavity in the surface
  • Feathers - an internal crack or fissure, appears light and feather-like, sometimes transparent without magnification
  • Clouds - a cluster of pinpoint inclusions, which can make a diamond appear milky or hazy
  • Knot - a small crystal that breaches the surface of the diamond, like a tiny bump on the surface
  • Graining - like you might find in wood, long streaks or lines that can look like scratches within the diamond, usually more visible from certain angles of the diamond
  • Twinning wisp - these show the moment a diamond stopped then restarted growing; often two amalgamations of pinpoints, needles, feathers and cloud inclusions that point to separate phases of growth
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The diamond clarity scale

Clarity is graded on a sliding scale, and is listed using combinations of letters and numbers, from FL (flawless) to I3 (very heavily included), with VS2 (very slightly included) to SI1 (slightly included) recognised as the best range for value with eye-clean beauty. Flawless diamonds, or those with negligible inclusions, are the rarest and most valuable of all.

Diamond clarity scale showing inclusions vs grade

The diamond clarity scale

Clarity is graded on a sliding scale, and is listed using combinations of letters and numbers, from FL (flawless) to I3 (very heavily included), with VS2 (very slightly included) to SI1 (slightly included) recognised as the best range for value with eye-clean beauty. Flawless diamonds, or those with negligible inclusions, are the rarest and most valuable of all.

When grading a diamond for clarity, lots of things are taken into account – how clear the inclusions or blemishes are under magnification, where and how they are positioned within the diamond, their size, colour, and of course how many there are.

Diamonds are viewed from the top down when they are graded, so the marks that you’ll see (under magnification or not) when the diamond is set in your ring are recorded. Diamond clarity is graded under 10x magnification, so even those not apparent to the naked eye are taken into account. Each flaw or blemish is mapped out on a diagram to catalogue the diamond’s clarity, and the diamond is awarded a grade, such as ‘VS2’ or ‘SI1’.

Can diamond clarity impact its sparkle?

To an extent, i.e. from ‘Flawless’ right down to ‘Slightly Included 1’, any inclusions within the diamond will not impact its sparkle. Diamonds graded any lower, however, will have inclusions that could inhibit the diamond’s sparkle. Heavy inclusions interfere with internal light reflection, minimising the light return that leaves the diamond to meet your eye. So in short, only diamonds graded ‘Slightly Included 2’ and lower will have inhibited sparkle due to inclusions. See the diagram below to compare light return in a minimally included diamond versus a heavily included diamond.

Comparing sparkle in a minimally included diamond vs a heavily included diamond

Why you should compromise on diamond clarity

Clarity is the ideal characteristic to compromise on when purchasing a diamond as inclusions are blemishes that are typically invisible to the majority of viewers. Reduce the cost of your diamond by looking between VS2 to SI1 grades, which won’t be flawless but will appear clear to the naked eye. You should only be able to see inclusions in VS2 to SI1 diamonds with a microscope.

If you look lower than SI1, you’ll start to spot inclusions without the aid of magnification, and heavy inclusions can even reduce the brilliance of the stone as the marks interfere with light return. Without a microscope or loupe, you probably wouldn’t be able to tell the difference between a FL diamond right down to SI1.

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