The GIA International Diamond Grading System™.

The GIA Diamond Clarity Scale is the global language for diamond clarity grading. Wherever you go in the world, whatever language is spoken, when buying a diamond, today you will likely hear terms like VVS1 or SI2 used to describe clarity.  Every diamond is evaluated under 10x magnification and assigned a clarity grade. A flawless diamond would receive an (FL) clarity grade; a diamond with obvious inclusions might receive a clarity grade of I3. Diamond clarity grades are based on the number, size, relief, nature, and location of characteristics. The clarity rating of a diamond is a reflection of the overall appearance of the stone – although many of these characteristics will likely not be visible to the naked eye.  Every diamond is truly unique, however most diamonds you see in jewelry stores fall between VS (very slightly included) and the SI (slightly included) on the clarity grading scale.

1 Universal System. 11 Grades.  All under 10x magnification

Flawless (FL) – No inclusions and no blemishes visible.
Internally Flawless (IF) – No inclusions visible but does have blemishes.
Very, Very Slightly Included (VVS1 and VVS2) – Inclusions so slight they are difficult for a skilled grader.
Very Slightly Included (VS1 and VS2) – Inclusions are observed with effort but can be characterized as minor.
Slightly Included (SI1 and SI2) – Inclusions are noticeable.
Included (I1, I2, and I3) – Inclusions are obvious which may affect transparency, brilliance and durability.