A diamond is the hardest substance known to man. The only way to cut a diamond is by using another diamond. Cut Cut is the factor that determines the brilliance of a diamond. Each of the stone's facets must be placed by the diamond cutter in exact geometric relation to one another. The fewer the inclusions, the clearer, more brilliant and more expensive the diamond.
Flawless diamonds are extremely rare.
Depending on the stone's size, a single increase in color grade can boost a value of a diamond by thousands per carat. A traditional engagement diamond is colorless. In nature diamonds can also occur in shades of red, pink, blue, green and deep yellow. Size alone is almost meaningless unless you consider cut, clarity and color. A large stone is not very valuable if it lacks brilliance, purity and high-grade color .