Clarity is the next of the 'Four C's'. It often requires magnification to determine clarity. Diamonds are graded at a 10X or 10 power magnification.
The little spots and flaws we see inside a diamond are called inclusions.
Some types of inclusions are more noticeable than others. The number, location and nature of the inclusion or inclusions determine the clarity grade of each diamond. The parameters of each clarity grade are very clearly defined. The GIA clarity grading system works under the following definitions.
Clarity grading starts at Flawless. There are no tolerances within the Flawless category. It is very simple: if there is ANY inclusion in a diamond it is not Flawless. Next we have IF or Internally Flawless. This means that the diamond is internally flawless but can have some minor external blemishes. Subsequent clarity grade categories are each divided into 1 and 2 subsections.
In the VVS 1 and 2 categories the inclusions are minute and appear as a tiny little white speck of dust or several tiny specks. These are called 'pin point' inclusions and by definition they are not eye visible. In a VVS diamond the inclusion or inclusions occur near the perimeter of the stone.
In the VS 1 and 2 categories the types of inclusions are similar. There are either more of them or fewer but larger ones. They are still not eye visible and may be located anywhere in the stone.
By the time we come to the SI 1 and 2 categories, the number of the small dust-like inclusions has either increased again or they have changed in nature to include a so-called dark inclusion. By definition, in diamonds in the SI 1 category the inclusions are still not eye visible. The inclusions in an SI 1 clarity diamond can only be seen with a microscope. There are more of them in these diamonds than in VS clarity diamonds and they may also be larger. By definition in the SI 2 category, when viewed 'face up', diamonds still appear eye clean. That is to say, the inclusions are there but they cannot be seen with the naked eye when examined through the table. When the stone is turned upside down, that is point up, it will be possible to see one so-called dark inclusion. If an inclusion is eye visible when the diamond is face up it cannot be graded as an SI 2 clarity.
Diamonds in the I 1 clarity category usually have a 'face up' eye visible inclusion, an accumulation of both white and dark inclusions and or possibly a 'feather'. A feather is a separation in the crystal lattice of the stone that actually looks like a feather. Generally, even where there are no other inclusions present, the presence of a feather inclusion will usually put a diamond directly in the I clarity classification. Diamonds of I 2 clarity grade display several easily eye seen inclusions.