Because diamonds formed deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes).
Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA International Diamond Grading System™, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).
Every diamond is unique. None is absolutely perfect under 10× magnification, although some come close. Known as Flawless diamonds, these are exceptionally rare. Most jewellers have never even seen one.
The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, colour or relief and quantity of clarity characteristics visible under 10× magnification.
- Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification
- Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification
- Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification
- Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification
- Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification
- Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance
How did the GIA Clarity Scale come about?
Like the colour scale, GIA’s clarity grading system developed because jewellers were using terms that were easily misinterpreted, such as "loupe clean" or "piqué". Today, even if you buy a diamond in another part of the world, the jeweller will likely use terms such as VVS1 or SI2, even if their language is French or Japanese instead of English.