A round brilliant has 58 facets. A facets is a flat, polished plane designed to yield the maximum amount of light to be reflected. This reflection is known as brilliance. Brilliance which is the combination of all the white light reflections from the surface and the inside of the stone. Brilliance gives a polished diamond its brightness.
Dispersion is the separation of the white light into spectral hues.
Dispersion is the rainbow colors you see in a prism. Scintillation is the flashes of light when the diamond, light, or the observer moves. A poorly cut diamond will actually loose light and appear dull. There are two main parts to the make of a diamond. Proportions and Finish.