I1, I2 and I3 (included)

How to read it

I1, I2 and I3 are the lowest three of the 11 grades on the GIA clarity scale. GIA describes their inclusions as obvious under 10× magnification and often visible with the unaided eye, and says they may affect transparency and brilliance; its photograph of an I3 stone shows how many inclusions and blemishes can make a diamond look off-color, pitted and scratched. GIA’s own history of the terms notes that included replaced the older word imperfect.

Also searched as: I1, I2, I3, included diamond.

Inclusions and durability

GIA says an inclusion that could damage the stone occasionally affects the clarity grade, and that this usually applies only to I diamonds. Inclusions near the girdle, the narrow edge between the crown and the pavilion, can leave a cut diamond more open to damage: a knock on a feather or another surface-reaching inclusion can chip it, and GIA counts very deep feathers, reaching about a third of the way into the stone or more, as a possible durability concern.

Piqué

On HRD Antwerp’s scale the three grades below SI2 are piqué, P1 to P3. GIA lists piqué, with loupe clean, among the imprecise terms jewelers used before its scale, and its own word for these grades is included.

Laser drilling and fracture filling

Laser drilling bores a narrow channel from the surface to a dark inclusion so that it can be vaporised or bleached. GIA grades laser-drilled diamonds, records the drill holes as inclusions, and lists a drill hole first on the report. Fracture filling hides fractures with a glass-like material; GIA does not grade fracture-filled diamonds, and says the filling must be disclosed by the seller.