The Four C's of a Diamond

Before I prepare to start my shopping for the perfect ring for the perfect girl, I should probably do a little research on exactly what I should be looking for.
The Four C's of a diamond:
Cut- we are more interested in the proportions of the diamond as opposed to its shape. Every diamond regardless of its shape gets it brilliancy and scintillation by cutting and polishing the diamond facets to allow the maximum amount of light that enters through its top to be reflected and dispersed back through its top.
Color- The best color for a diamond is no color at all. A totally colorless diamond allows light to pass through it easily, resulting in the light being dispersed as the color of the rainbow. Colors are graded totally colorless to light yellow. The differences from one grade to the other are very subtle and it takes a trained eye and years of experience to color grade a diamond.
Clarity- The clarity of a diamond is determined by the amount and location of flaws, or blemishes, in the diamond when viewed under 10 power (10x) magnification.
Carat- The weight of a diamond measured in carats. As the carat weight of a diamond increases so does its rarity and therefore its price.