Diamonds are gems with an eternal and unique charm for their strength and brightness. The four factors that determine the value of the diamond are the four "C": carat, cut, color and clarity. Carat: indicates the weight of the stone. Cut: Indicates whether the proportions of the cut of the diamond, and the shape given to the gem. The cut is the only one of 4C to be influenced by human intervention, and is important because it determines the refraction of light, and then the brightness of the stone. The most famous is the brilliant cut.