Disclosed is an improved system and method to treat an edge of a material for determining a property of such material through measurements of electromagnetic waves. The system and method are operative to mitigate the adverse effects caused by the interaction between an electromagnetic wave and an edge of a sample of a material under test. The system and method define a configuration to block and significantly attenuate the propagation of electromagnetic waves that may reach an edge of the sample being evaluated. This configuration reduces the undesired effects caused by edge-diffraction that may interfere with the measurement of desired electromagnetic waves for material evaluation. As a result, a property of a material under test can be measured more accurately, especially near the edges of such material. In addition, the system and method enable the evaluation of a small-size sample of a material.