Flawless – Internally Flawless
The rarest of rare diamonds, known as Flawless (FL) diamonds, are those with no internal features and no external features or blemishes visible at ten times magnification. An Internally Flawless (IF) diamond will also have no internal features, but may exhibit a minute scratch left over from polishing.
Very Very Slight (VVS)
Very Very Slightly (VVS) included diamonds are those with minute inclusions so small that they are extremely difficult for even a skilled diamond grader to see at ten times magnification. A VVS1 diamond may have a single pinpoint, whereas a VVS2 may have a pinpoint or two and tiny feather as its internal features.
Very Slight (VS)
Divided into VS1 and VS2, Very Slightly (VS) included diamonds have minor internal features deemed difficult for a skilled grader to detect at ten times magnification. A VS1 diamond may have a small crystal, a feather, a tiny cloud of inclusions, or a pinpoint or two whereas a VS2 diamond could have for example, a tiny cloud, a few small needles or a small included crystal. In extremely rare cases, very large diamonds, or in significantly transparent fancy shapes like emerald cuts, a VS inclusion may be just barely visible to the unaided eye.
Slightly Included (SI)
Divided into SI1 and SI2, Slightly Included (SI) diamonds are those with features that are obvious at ten times magnification. A typical SI diamond might have a cloud, a feather and an included crystal of another mineral. Neither the diamond's transparency nor face up appearance may be affected by these inclusions. In some rare cases, large diamonds, or transparent fancy cuts, an SI clarity feature may be just visible to the unaided eye.
Included (I-1, I-2, I-3)
Divided in I-1, I-2 and I-3, included diamonds are those with features that are visible to the unaided eye and may even affect the durability of the diamond. Included diamond may have obvious features such as large contrasting crystals, heavy clouds and distinct cleavages. These diamonds are excluded from Forevermark.
Colour
Forevermark inscribes diamonds from D to L as well as all fancy colours. In this scale, ‘colourless’ diamonds D, E, and F show so little difference that it takes an expert with sample diamonds of known grades to distinguish one from another.