Oval Round, etc. Cut here is referring to how well proportioned a diamond is. Cut too shallow or too deep will enable light to escape or pass through the diamond. Result, not as brilliant. A well proportioned loose diamond manages light more effectively.
Light is reflected from facet to facet and allows more fire or sparkle.
Color - Diamonds are found in a range of colors, it is the first thing you see. Color ranges are colorless, white, silver, subtle yellow, brownish to very yellow. Diamonds can also be found in fancy colors - pinks, reds, purples, greens, blues and even black. These are very rare and are called fancy color diamonds. Clarity - Most diamonds contain very tiny natural birthmarks sometimes referred to as inclusions.