Clarity refers to internal (inclusions) and on the surface characteristics (blemishes) within or on a diamond when viewed with 10x magnification under standard viewing conditions. The EGL Platinum clarity scale includes twelve grades ranging from Flawless to I3.
The EGL Platinum clarity grading scale:
FLAWLESS GRADE (FL) is used to describe diamonds in which a skilled observer, under favorable lighting conditions, cannot see any inclusions or surface blemishes, after thorough examination with a binocular microscope at ten power magnification or with a 10x corrected loupe. Small extra facets on the pavilion near the girdle, not visible when viewed from above, are permitted, as are small naturals when they are confined to the girdle and do not flatten the girdle outline. Internal graining is permitted, provided it does not draw any color or texture and is not observable through the crown.
INTERNALLY FLAWLESS GRADE (IF) describes diamonds which have no internal characteristics observable under the same conditions as described, but which have minor surface blemishes that do not penetrate the stone. Surface grain lines are permitted provided they are not too thick or numerous so as to detract from the beauty of the stone. Internal graining is permitted, provided it does not draw color or texture.
VVS1 & VVS2 GRADES (VERY, VERY SLIGHTLY INCLUDED) are used to describe diamonds which have very, very small inclusions which are difficult for a skilled observer to see under the conditions as described. Colored or textured graining is permitted, provided it is not observable through the crown.
VS1 & VS2 GRADES (VERY SLIGHTLY INCLUDED) are used to describe those stones with very small inclusions which can be difficult to observe under the conditions as described. Except for larger stones or occasionally with Emerald cut diamonds, these are rarely visible to the unaided eye.
SI1, SI2 & SI3 GRADES (SLIGHTLY INCLUDED) are used to describe stones with small inclusions which are usually obvious when viewed under the described conditions.
I1, I2 & I3 GRADES (also called PIQUE; P1, P2, P3) are used to describe stones with medium or large inclusions (Piques) which are usually obvious to a skilled observer with the unaided eye under favorable lighting conditions.