November 15, 2012
A diamond's size is always the first thing we notice, but diamond clarity is just as important in determining a diamond's value. Diamond clarity is a measurement of a diamond's blemishes and internal characteristics, or inclusions. All other factors being equal, the higher the clarity grade, the greater the value of the diamond.
Clarity is one of the four Cs of diamond grading; the others are color, carat, and cut. The clarity grade is based on the appearance of the diamond under ten times magnification -- hence those funky little eyepieces you see gem dealers using.
Don't feel bad, though; minor inclusions or blemishes are helpful in identifying diamonds, as well as helping to distinguish a natural diamond from an artificially created synthetic diamond. (Why, you might ask, is a synthetic diamond, with no flaws, worth less than a natural diamond with its inherent blemishes? Because shut up.)
GIA Diamond Clarity Chart
Here is the Gemological Institute of America's (GIA) diamond clarity grading scale:
* Percentage of market refers only to stone in the gem-trade. If a diamond is below I-grade clarity, it is considered industrial grade, and unfit for jewelry. Of all diamonds mined, only 15% are I-grade or above.
Diamonds in the flawless category (FL) show no inclusions or blemishes at 10x magnification. They are exceptionally rare. Because of their rarity, they are almost never worn in jewelry, but rather are displayed in collections or museums.
Internally Flawless category (IF) diamonds show no inclusions at 10x magnification, but have small blemishes a skilled grader can spot on the diamond's surface. They're extremely valuable, and are often considered, like flawless gems, to be too valuable to simply wear.
Very, Very Slightly Included category (VVS) diamonds show tiny inclusions that are very difficult for a skilled grader to see under 10x magnification. There are two grades in this category; VVS1 is a higher clarity grade than VVS2.
Very Slightly Included category (VS) diamonds have minor inclusions that are somewhat hard for a trained grader to see at 10x magnification. The VS category also is divided into two grades; VS1 is a higher clarity grade than VS2.
Slightly Included category (SI) diamonds have noticeable inclusions that are easy for a trained grader to see under 10x magnification. The SI category is also divided into two grades; SI1 is a higher clarity grade than SI2.
Included category (I) diamonds have obvious inclusions that are clearly visible to a trained grader under 10x magnification. Included diamonds have inclusions that are usually visible without magnification or have inclusions that threaten the durability of the stone. The I category grades are, from highest to lowest clarity, I1, I2, and I3.
There are several types of inclusions and blemishes, which affect a diamond's clarity to varying degrees. Features resulting from diamond enhancement procedures, such as laser lines, are also considered inclusions or blemishes.
The diamond industry uses the term "internal characteristics" instead of "inclusions". For natural diamonds, the "internal characteristics" in the diamond are growth crystals that give the diamond its character and unique fingerprint. When diamonds are graded they are magnified at 10x power.
As you can see from all this, the grading process for diamond clarity alone is very involved, but it's still only a quarter of the total grading process. For more information, see the diamond cut chart, diamond color chart, and this diamond carat chart.
Content adapted from Wikipedia.org; text available under Creative Commons Attribution-ShareAlike License. If you have corrections for any of this content, please email me!