CUT The cut is one of the four C's and is therefore one of the most important criteria for determining the quality of a diamond, as it is largely responsible for its brilliance and bewitching sparkle. You have to know that the rainbow-colored shine of a diamond, its so-called fire, comes into its own with an optimal cut. The connection between the cut and the fire of a diamond It is thanks to the high dispersion of diamonds that they shimmer in the color spectrum of the rainbow - provided they have an advantageous cut. A diamond is naturally colorless, but the various degrees of refraction of the incident light rays create the multitude of colors. However, if the cut is too pointed or too flat, this effect is lost. The light only travels from facet to facet and is reflected back into the eye of the beholder if the proportions are ideal.