Internally Flawless - No inclusions visible under 10-power magnification.
VVS1-VVS2 - Very, very slight inclusions. The inclusions are minute and extremeley
difficult to locate under magnification.
VS1-VS2 - The inclusions are very slight and minor. They will be difficult to locate
under magnifiation.
SI1-SI2 - Slight inclusions that are noticeable under magnification. Some SI2 inclusions
can barely be seen with the unaided eye.
I1-I2-I3 - Imperfect stones that have a range of inclusions visible to the naked eye, as well
as faults that vary from just noticeable to glaringly obvious.