The diamond crystal lattice often presents gaps that can depend from various kinds of inclusions. Pure diamonds are considered those diamonds that when cut and observed with a 10x magnification lens, do not show any inclusions.

The gems with minor or no inclusions are rare and are those that are given a higher commercial price.

External imperfections, usually scratches or lack of material, should not be considered in determining the purity, as they can be removed with an appropriate process of cutting or polishing the gem. Only an experienced cutter can consider the appropriateness of such interventions. This is still a characteristic which also determines the quality and therefore also the value of the diamond and they are to be included in the certification of the gem.

IF or LC (internally flawless or loup clean) = pure to the lens, under 10x magnification, inclusions are not visible, rarest clarity grade.

VVS 1-VVS 2 (very very small) = inclusions are extremely difficult to detect with a 10x magnification

VS1-VS2 (very small) = very minor inclusions difficult to detect with 10x magnification

SI1-SI2 (small inclusions) = small inclusions easy to detect with 10x magnification

P1 (I1) (Piqué) = inclusions visible immediately with 10x magnification and difficult to detect with the naked eye through the crown

P2 (I2) (II Piqué) = large and numerous inclusions are easily visible to the naked eyethrough the crown.

P3 (I3) (III Piqué) = large and numerous inclusions, very easily visible to the naked eye through the crown. Significant reduction of the brilliance of the diamond.