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Clarity is up next in Joslin’s 4 Cs of Diamonds series.

Clarity is all about the diamond’s purity. This is how the presence or absence of flaws within a stone is assessed. Flaws are termed as internal, or “inclusions,” and external, or “blemishes.” Natural diamonds are formed by tremendous heat and pressure deep below Earth’s surface over the course of millions of years. These extreme conditions rarely produce a “flawless” diamond, and most will have any number of blemishes and/or inclusions. In fact, less than 0.5% of diamonds are classified as flawless.

Gemologists grade clarity on a scale ranging from “I,” meaning included, to “FL,” meaning flawless. For a diamond to be graded FL, it must have absolutely no visible flaws under 10-power magnification. For the most part, diamonds that fall in the upper half of the scale (IF, VVS1, VVS2, VS1, and VS2) will generally be eye-clean, meaning their inclusions and blemishes are not visible to the naked eye.

Clarity Grading Factors

Some common factors that must be considered by the gemologist while determining a diamond’s clarity grade are:

  • Size of inclusions. The larger the inclusion, the larger its impact on the diamond’s appearance. Also, the larger the diamond, the larger its inclusions will be.
  • Nature of inclusions. This refers to the type and depth of the inclusion (more on this later).
  • Number of inclusions. More inclusions mean less sparkle.
  • Location of inclusions. Inclusions that are closer to the center of a diamond’s table will be more visible.

Example of clouding from the GIA.

There are numerous types of inclusions that appear in diamonds:

  • Clouds: Clusters of pinpoint inclusions that can make a diamond look hazy or dull if they are particularly numerous or large.
  • Crystals: These are various mineral crystals trapped within the diamond during its formation, often appearing as small, dark, or colorless spots.
  • Feathers: These are small, feather-like fractures or cracks within the diamond. They can vary in size and visibility, and large feathers can affect the diamond’s durability.
  • Needles: These are long, thin, white or colored inclusions, often crystals of minerals like rutile or peridotite.
  • Graining: This refers to irregularities in the diamond’s crystal structure. They can appear as lines, streaks, or patterns and can affect the diamond’s transparency.

    Example of graining from the GIA.

  • Knots: These occur when part of a diamond’s crystal extends to the surface. They are more vulnerable to chipping, and so present durability concerns.

Since most diamonds have flaws in some form, experts have a variety of ways to present these stones in different jewelry applications that minimize the effects of inclusions or blemishes and amplify the diamond’s brilliance instead. For example, a diamond may have a lower clarity grade because of inclusions along its edge, but when placed in the right setting, the inclusions are hidden and light is redirected, enhancing its sparkle. The diamond professionals at Joslin’s have decades of experience finding the best diamond for each customer, taking into consideration their jewelry needs and budget.

Interested in learning more about diamonds? Check out Joslin’s previous posts about the 4 Cs of Diamonds!


Watch the video below to hear what Joslin’s Jewelry’s very own diamond expert, Gary Joslin, has to say about diamond clarity!