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Should I Care about Diamond Clarity?

One of the 4Cs, clarity, can be affected by inclusions and blemishes, making a diamond less sparkling and clean-looking.

You’ve probably noticed how some diamonds twinkle and flash while others just sit like cloudy ice, dull and uninteresting. The flash happens when light enters the diamond and bounces off the planes of the facets. But if anything stops that light along its path, it will impair the reflections and refractions. This is where one of the 4Cs — clarity — comes in.

Two things can happen to stop the light dead in its tracks: inclusions and blemishes.

  • Inclusions are tiny imperfections gathered inside almost every diamond as it forms under intense heat and pressure deep underground. They range from pieces of mineral to stress fractures called feathers. Sometimes a group of inclusions will make a diamond appear cloudy under magnification.
  • Blemishes are on the surface of the diamond and include cavities, nicks, scratches and naturals, which are a small part of the original rough diamond left on the polished diamond during the diamond cutting process.

Under the scope

A jeweler will likely use a gemological microscope or a loupe to show you the inclusions and blemishes when you’re considering a diamond for an engagement ring. Remember that almost every diamond has inclusions and/or blemishes. However, many are visible only under magnification and do not affect the diamond’s beauty when seen with the naked eye.

Clearly speaking

If nearly all diamonds have flaws, why do they affect value differently? Consider the five factors a diamond grader examines when evaluating clarity:


The bigger the inclusion or blemish, the lower the clarity grade and value.


The more inclusions or blemishes — and the more visible they are — the lower the clarity grade and value.


The position of inclusions affects how easily they may be seen when viewed looking at the diamond top-down. Sometimes when viewing them under magnification, one flaw may appear to be many. Diamond cutters try to position these internal imperfections under the crown facets or near the girdle to have less effect on the clarity grade.


This essentially indicates whether the “characteristic” (another name for inclusions and blemishes) is internal or external and whether it threatens the diamond’s durability.

What it means

After evaluating all five factors, a grader will assign a grade from a scale that has six categories and 11 grades (if using the Gemological Institute of America system). Invest a few moments now to familiarize yourself with the possible grades:


(FL) diamonds have no inclusions or blemishes visible using 10X magnification.

Internally Flawless

(IF) diamonds have no inclusions and only blemishes visible to a grader using 10X magnification.

Very, Very Slightly Included

(VVS1 and VVS2) diamonds have inclusions that are very difficult for a grader to see using 10X magnification.

Very Slightly Included

(VS1 and VS2) diamonds have minor inclusions that range from difficult to somewhat easy for a grader to see using 10X magnification.

Slightly Included

(SI1 and SI2) diamonds have inclusions that are noticeable to a grader using 10X magnification.


(I1, I2, I3) diamonds have inclusions that are clearly visible and usually without magnification.

The American Gem Society grades clarity on a scale of 0 to 10, and the numbers correlate with the GIA system — with a few differences. The flawless and internally flawless categories are combined, and there is a notation whether the diamond is free from external blemishes. In addition, the three Included grades on the GIA scale are divided into four grades on the AGS scale.

Treatment and enhancement

You may have heard that some diamonds are treated or enhanced in some other way to improve their appearance. Reputable dealers must disclose this treatment, which is considered permanent.

Fractures, meanwhile, can be filled. Reputable filling companies use a material that shows a flash of color when viewed closely, and reputable dealers disclose this treatment. Fracture filling is not as permanent as the diamond because a torch used in setting diamonds into a piece of jewelry repair can melt the filler, thus removing it.

Why you should care

Obviously, clarity plays a part in how light moves within the diamond, creating the flash and the illiusion that the diamond is lit from within that people want to see. It’s also a factor in the rarity and the overall price. The better the clarity, the more valuable and expensive it is.

If you don’t know whether your diamond has been treated to correct its clarity, you could pay more than the diamond is worth.

Knowing what clarity is, and what the evaluation means on a lab report, makes you a more informed and — ultimately — smarter diamond buyer.

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