Clarity, one of The Four “C”s of judging diamond quality, refers to the presence of surface or internal flaws within a diamond caused during its formation or the cutting process.

Diamond Blemishes

When the marks occur on the surface, they are known as blemishes. The most common types of blemishes include naturals, a small part of the original rough diamond’s surface which has been left on the cut diamond; surface graining, transparent stress lines that appear on a diamond’s surface; and extra facets, that are usually cut to remove a near-surface inclusion and raise the clarity grade of a stone.

Diamond Inclusions

When these marks occur internally, they are called inclusions. The most common types of inclusions include crystals, tiny bubbles representing small minerals that were absorbed into the diamond while it was growing; pinpoints, crystals so tiny that they only appear as little dots under 10x magnification; needles, needle-shaped included crystals; knots, an included diamond crystal that reaches from the inside to the surface of a polished diamond; chips, small, shallow openings on a diamond’s surface; cavities, larger chips often created when an included crystal is removed from near the surface, leaving an indentation; feathers, small stress fractures within a diamond; internal graining, stress lines inside a diamond; and clouds, a grouping of inclusions that resembles a cloud under magnification. All diamonds have such flaws. These imperfections serve as the “fingerprint” of a stone and make each one unique. However, inclusions and other flaws can interfere with the passage of light through a stone, diminishing its sparkle – therefore, the fewer (or smaller) the inclusions, the more valuable the diamond.

Flawless Diamonds

In the rarest and most expensive diamonds, the inclusions are too tiny to see even at 10x magnification in good light, which is why these stones are called “flawless” (FL) or “internally flawless” (IF) according to the quality analysis system of the Gemological Institute of America. At the other end of the scale are “imperfect” stones (I grades) with visible faults that mar their natural beauty.

The GIA Diamond Clarity Grading System

  • FL (flawless) – No external marks or internal inclusions visible to a trained eye under 10x magnification.
  • IF (internally flawless) – Only minor surface blemishes but no internal inclusions visible to a trained eye under 10x magnification.
  • VVS1, VVS2 (very, very slightly included) – Few, very small inclusions and/or finish faults, difficult for a trained eye to see under 10x magnification. Typical flaws include tiny pinpoints, faint clouds, tiny feathers, or internal graining.
  • VS1, VS2 (very slightly included) – Very small inclusions and/or finish faults, somewhat difficult for a trained eye to see under 10x magnification. Typical flaws include crystals, feathers, distinct clouds and groupings of pinpoints.
  • SI1, SI2 (slightly included) – Small inclusions and/or surface blemishes easily seen under 10x magnification, but not visible face-up to a naked trained eye. Typical flaws include crystals, clouds and feathers.
  • I1 (imperfect 1) – Inclusions and/or finish faults visible under 10x magnification, but hard to see with the naked human eye. Little effect on the brilliancy of a stone.
  • I2 (imperfect 2) – More and/or larger inclusions and surface blemishes easily seen without 10x magnification. Some diminished brilliancy within stone.
  • I3 (imperfect 3) – Many and/or very large inclusions and surface faults easily seen without 10x magnification. The severity of the inclusions obviously disfigures the stone. Rarely used for jewelry purposes (most often used as industry diamonds).
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