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) or on its surface (called blemishes).
Clarity refers to the degree to which these imperfections are present. Diamonds which contain numerous or significant inclusions or blemishes have less brilliance because the flaws interfere with the path of light through the diamond.
The position of an inclusion affects how easily it can be seen. Diamond cutters make every effort to cut a stone so that inclusions are not visible through the table of the finished diamond.
The preferred position for inclusions is under the bezel facets or near the girdle because they are harder to see there.
Almost all diamonds are graded for clarity using the 11 point diamond clarity scale created by the GIA, including diamonds which were not actually graded by GIA (every diamond we use is GIA certified). In grading diamond clarity, the GIA considers the number, size, colour, reflectivity, and position of every flaw visible under 10x magnification.
Flawless: No inclusions or blemishes are visible to a skilled grader using 10x magnification.
Extremely rare; less than 1 in 5,000 jewellery quality diamonds are rated FL.
Internally Flawless: No inclusions, only blemishes are visible to a skilled grader using 10x magnification.
FL and IF diamonds appear identical unless viewed under 10x magnification by a skilled grader. Less than 3% of jewellery quality diamonds are rated IF.
Very, Very Slightly Included: Inclusions are difficult for a skilled grader to see under 10x magnification.
VVS1 inclusions are typically only visible from the pavilion, while VVS2 inclusions are visible from the crown. In each, the inclusions are invisible to the eye, appearing identical to the higher grades unless viewed under 10x magnification by a skilled grader.
Very Slightly Included: Inclusions are clearly visible under 10x magnification but can be characterised as minor.
Inclusions are not visible to the naked eye. Perhaps 1 in 100 untrained observers can detect VS2 inclusions with the naked eye, on close inspection under ideal conditions.
Slightly Included: Inclusions are noticeable to a skilled grader using 10x magnification.
SI1 is the lowest grade with flaws often invisible to the naked eye. SI2 inclusions are usually visible to the naked eye, although they will require close inspection.
Included: Inclusions are obvious under 10x magnification and may affect transparency and brilliance.
I1 diamonds have inclusions that are almost always visible to the naked eye. I2-I3 diamonds have pronounced inclusions, and in the case of I3 may even affect the diamond's durability.