Types of Inclusions
Clarity Enhancements
There are two main methods for enhancing the clarity grade: laser drilling and fracture filling. Both are not perfect and result in a lower price for the stone.
Laser drilling is used to drill inside the diamond and evaporate dark coloured crystal inclusions. The original inclusion can be fully removed, but the laser leaves a visible white trail behind going from inside the diamond to the surface. These laser lines are often reflected off the facets several times to appear as multiple. This method is safe and removes the inclusions permanently. Diamonds treated with laser drilling are accepted for grading at labs such as GIA.
Fracture filling is a temporary solution to a problem of low clarity, and fracture filled diamonds are not accepted to be graded by GIA since the appearance of the filling may change, affecting the grade. To fill a fracture or a crack in a diamond (or a line from laser drilling) a special type of glass-like substance is used. When filled, the inclusions no longer look white, but transparent. The problem with this treatment is that the filling is not as heat resistant as the diamond itself and can get damaged while setting the stone, especially if the setter is unaware that the diamond was fracture filled. In addition, the refractive index of the filling is not identical to that of a diamond and this results in bright coloured flashes of light coming from the filling when the diamond is observed under a certain angle, giving away the location of the filled inclusions. Also, due to the liquid origin of the filler, bubbles often form inside the filled fracture that are readily visible under magnification.
While such enhancements can substantially increase apparent clarity of the stone, they rarely result in diamonds graded VVS or higher. Part of the reason for this is the imperfection of the actual techniques used. The most important warning however, is that none of these enhancements address the durability issues common to I2 and I3 graded diamonds — the common candidates for clarity enhancements. This means that the overall quality of a clarity enhancemed VVS is much lower than of a natural VVS.
