Cut is the most important part of your diamond. It will determine the sparkle of your diamond. If a diamond has a poor cut the diamond could appear to be dull and have no life to it, when a diamond has an Excellent to Good Cut, the diamond will have a lot of fire and sparkle from every angle of it.
Color is the second most important part to your diamond because the human eye can detect color and it can be seen to the naked eye. To maximum the size of your diamond getting a Near Colorless Diamond will face up white and will not show any yellow to the naked eye.
Clarity is the third most important part to your diamond because most imperfections (inclusions,) will not be detected to the naked eye and can only been seen under a Professional Magnification.
Carat Weight is also a very important characteristic part of your diamond. Diamond Size is measured by weight and not by size. A Diamonds cut will impact the appearance of a Diamond whether the Diamond is too Shallow or to Deep.