The 4 C's - A Guide to Diamond Clarity and Diamond Grading

The subject of diamond clarity is an interesting one. The impurities in diamond create a “fingerprint” that is unique for every diamond. In that regard they are quite helpful in providing identifying characteristics. And while there are many types of diamond inclusions, and they are the subject of much interest and discussion on the part of diamond shoppers, the practical impact of many diamond clarity grades on diamond beauty is surprisingly small!
The GIA (Gemological Institute of America) created the diamond color and clarity grading scale in the 1950’s. Most laboratories use the same framework today. The clarity scale ranges from Flawless (no internal or external features visible to a trained grader under 10x magnification) to imperfect diamonds that are so heavily included that they lack transparency and/or have durability issues. While a high percentage of commercial jewelry is made using imperfect diamonds, the percentage of laboratory certified diamonds in the middle and upper portion of the scale is quite high.
There are eleven clarity grades in the GIA system and it can be said that diamonds within the top six grades are almost certain to be clean to the naked eye, or “eye clean”, when viewed normally in the face-up position. When a diamond is clean to the naked eye and does not have clarity features that diminish light performance to an appreciable degree, the clarity grade has virtually no impact on the visual appearance of the diamond. Even if the diamond is six or seven grades down the scale! Clarity is the only one of the diamond 4 C’s where this is true.
In a sense it can be said that “Clarity is Rarity”. Diamond prices are generally predicated on rarity. The bigger, the cleaner and better color the diamond is, the higher the price. So, for the most part, until you get into the Imperfect range, the clarity grade only impacts price and has little or no bearing on beauty.

Diamond Clarity Grading Scale

Diamond Clarity Grading Scale
Diamond Clarity Grading Scale
FL - Flawless - no internal inclusions or external blemishes
IF – Internally flawless - no inclusions visible at 10x magnification but some minor blemishes.
VVS1 - Very, Very Slightly Included 1- inclusions extremely difficult to see at 10x magnification.
VVS2 – Very, Very Slightly Included 2 – inclusions very difficult to see at 10x magnification.
VS1 - Very Slightly Included 1 – inclusions difficult to see at 10x magnification.
VS2 – Very Slightly Included 2 – inclusions somewhat difficult to see at 10x magnification.
Si1 - Slightly Included 1 – inclusions somewhat easy to see at 10x magnification, can sometimes be seen with naked eye.
Si2 - Slightly Included 2 – inclusions very noticeable at 10x magnification, often possible to see with naked eye.
I1- Imperfect 1 – inclusions obvious with 10x magnification, and usually can be seen with naked eye.
I2- Imperfect 2 – Inclusions can be seen with naked eye and often compromises beauty or durability.
I3- Imperfect 3 – Inclusions that cause severe beauty and/or durability deficits.
Simulated Diamond Clarity Grading Scale from FL to I3
Simulated Representation of the Diamond Clarity Scale

Diamond Clarity vs Color

Color grades are also very small ranges along a continuum from colorless to strongly tinted, and many of the top grades look “white”. But people with very good color sensitivity can detect even small amounts of body color in a diamond. They can therefore discern differences in beauty in diamonds even at the top of the scale. Yet it is physically impossible for any human being to see an inclusion in a VVS diamond with the naked eye.
While the color grade might have more impact on beauty than the clarity grade in many cases, the quality of the cut has the greatest impact of all. Ideal cut diamonds enable the diamond to exhibit optimal light performance resulting in the greatest amount of fire brilliance and sparkle.

Diamond Inclusions – a World of their Own!

Some call them flaws while others call them beauty marks. But the range of characteristics falling under the definition of diamond inclusions is as wide as it is fascinating. Sometimes inclusions are responsible for very rare and interesting fancy colored diamonds such as opaque or translucent white and black diamonds. Sometimes single inclusions are particularly interesting in and of themselves; things sometimes trapped inside a diamond include rubies, sapphires, garnets, and even other diamonds! For more information and images please see our page on diamond inclusions.

Si1 Diamonds

Because diamonds with lower clarity grades are less expensive, shoppers looking for best value are particularly interested in those diamonds which are lower in grade but have no eye visible inclusions or any clarity features that might deprive the diamond of its fire, brilliance and sparkle. Si1 diamonds are extremely popular for precisely this reason.
But not all Si1 diamonds will fit the criteria above. Some do have eye visible inclusions, particularly larger diamonds. The term “eye-clean” means different things to different people and the definition can vary from vendor to vendor. So it is important to understand your own expectations to ensure proper communication with the merchant. The Whiteflash definition of eye-clean is:
No inclusions visible to the naked eye of a person with 20/20 vision when viewing the diamond in the face-up position at a distance of approximately 10 inches under normal overhead lighting.
And some diamonds may be technically eye clean but have features that impede light performance, leaving them less bright or fiery than they would otherwise be. Si diamonds with clarity grades based on features such as clouds, twinning wisps, and graining can sometimes have transparency deficits. It is wise to have an experienced expert review such diamonds before you are fully committed to a purchase, as these effects can sometimes not be obvious to the untrained eye. Shopping for a good Si1 can be a little tricky, but the payoff in value can be very worthwhile.
Diamond Plot and Keys to Symbols
Diamond Plot and Keys to Symbols
Magnified Diamond with Crystal Inclusions
Magnified Diamond with Crystal Inclusions
Generally speaking, moving to the VS range will remove the chance that clarity features will have any negative impact on the beauty of the diamond.


Fluorescence can sometimes impact transparency as well. Some diamonds with strong fluorescence can appear milky when exposed to strong ultraviolet light such as that found in direct sunlight. While fluorescence is normally just an identifying characteristic with no impact on diamond appearance in typical viewing environments, it is important to have an overall understanding of the topic when considering a fluorescent diamond.
Any meaningful discussion about the grade of a diamond assumes that the stone has a report from one of the top gemological laboratories such as GIA or AGSL (American Gem Society Laboratories). Only ethical, well-equipped labs with highly trained and experienced graders can be relied upon to give accurate and consistent grades.

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