Diamond clarity is directly related to the color, size, placement, and the number of inclusions in a diamond. As these inclusions are basically cavities composed of various materials, you can always enhance the clarity by reaching them out and cleaning the cavity. There are different methods discovered to clear out the cavity by filling them with appropriate materials. Below is a discussion on the clarity enhancement process of the different jewelry like the emerald cut engagement rings.
This is the only type of clarity enhancement sanctioned by the GIA. It goes through the process of boiling the diamond at deep pressure within a prepared acidic solution.
Substituting the Inclusion and Not Removing it
This only works for diamonds with black inclusions and find their way to the surface. Note that if the inclusion cavity does not feature on the outer region of the finished diamond, the acid will not be able to penetrate the inclusion.
Similarly, deep boiling is unable to fill the cavity. Instead, it just removes the black compound which fills it. Hence, this procedure is most useful where you have a noticeable black inclusion and substitute it using a lightly translucent inclusion.
This is the procedure that is done to the diamonds when black inclusions are unable to find their way to the surface. A microscopic hole is made using a laser beam. This starts at the surface and reaches the black inclusion inside the diamond. After the passageway is made, the diamond is deep boiled. This removes the black from the inclusion.
Installing a Tunnel Inclusion
In this process, a small yet undetectable tunnel on the surface of the diamond. This is actually used to replace the black tunnel which was present in its place.
Special Laser Drilling
This process is similar to laser drilling, but instead of creating a tiny tunnel starting at the surface of the stone to the inclusion within the diamond, it drills a plane through the diamond till it reaches the black inclusion
Note that the resulting laser-created inclusion is bigger than the tunnel that is otherwise created, it has two main effects. Firstly, as far as the diamond dealers are concerned, the mark leaves a much more real-looking surface behind. This is difficult to detect. Further, the flat plane inclusion can be easily filled when compared to the normal laser drill.
Above are the most prominent techniques of clarity enhancement used in diamonds.