Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth’s mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years.
Because they are formed deep within the earth, under extreme heat and pressure; virtually all diamonds contain “birthmarks”; small imperfections inside the diamond (called inclusions).
Many of these imperfections are microscopic, and do not affect a diamond’s beauty in any discernible way.
Clarity is one of the four Cs of diamond grading .Clarity refers to the degree from which a diamond is free from inclusions. Diamonds are assigned clarity grades based on what can be detected at a standard 10x magnification.
Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy.
The impurities in diamond create a “fingerprint” that is unique for every diamond. In that regard they are quite helpful in providing identifying characteristics. Clarity’s influence on value is directly related to the concept of rarity. Clarity scale includes eleven clarity grades ranging from Flawless to I3. Flawless diamonds are very rare and don’t have visible inclusions or blemishes. At the lower end of the scale are diamonds with inclusions that can easily be seen by the unaided eye.
No two diamonds are alike. Each diamond will poses its own unique set of inclusions and placement of inclusions. Hence, within a grading class, the range of inclusion may differ considerably. Never rule out a diamond just because it’s in the same clarity grade as the one you’re looking at.