To cut Parmigiano Reggiano, you must necessarily use the typical tool.
It is a characteristic knife, with short and pointed blade, almond-shaped.

The shape of Parmigiano Reggiano therefore does not cut but opens, to keep intact the internal structure and the natural graininess.

With the tip of the almond knife you draw a line that divides the shape in half, on the diameter of the two sides, continuing on the side (or scalzo).
Cut the crust along this line penetrating at times with the knife for a depth of a few centimeters: at the two extreme points of the diameter of one of the faces, in the middle of the side, 2 almond knives are vigorously stuck. In this way, acting as a wedge, the force developed makes open the shape of Parmiggiano Reggiano in two halves.

This process requires experience and attention because the opening is perfect only if the internal structure of the cheese has been able to oppose the same resistance in both the one and the other half.
Subsequent incisions, such as cutting or scaling, must also be made using the same method.
Thus, one half is further divided into two equal parts, which in turn will be divided into other equal parts.
In this way they are obtained from a shape pieces of Parmigiano Reggiano that have the same proportions between pasta and external crust.