The 4 C's - Clarity
The 4 C's that measure general "Diamond Quality"
When a diamond is growing, it grows around whatever is in it's way, including garnet and even other diamonds.
When the diamond cutter looks at a piece of rough, she tries to decide what the largest stone that can possibly come out of the rough would be. Taking into consideration the inclusions inside. Trying to avoid as many as possible, while getting a large stone as well.
Clarity Grades
Basic Explanations
VVS (Very Very Slightly Included) group refers to stones that require 10 power magnification to see any inclusions. This grade refers to stones in which inclusions are very difficult to see, and may be located near the outer areas of the stone, making them more difficult to see.
VS (Very Slightly Included) group refers to stones that still require magnification, but in which the inclusions are easier to see. They may also be more centrally positioned in the stone.
SI (Slightly Included) group refers to stones that still require magnification to see inclusions, but once magnified, easily reveal their inclusions. However, none are visible to the naked eye.
This grade includes SI1 and SI2.
I (Included) group refers to stones that have inclusions of such magnitude, that they are visible to the naked (unmagnified) eye. They may be merely visible, or may also effect the structural integrity of the diamond.
This grade includes I1, I2 and I3.