Diamond Cut
The cut of a diamond is crucial in determining the brilliance and therefore, the value of a diamond. A cut that is too shallow will allow light to pass right through the bottom of it, therefore not living up to its brilliant potential. A cut that is too deep forces the light to escape through its sides, therefore appearing dull and dark. And ideal cut bounces the light right back up and out, allowing it to shine and sparkle as a diamond should. Although width and depth are important in a diamond cut, a 3D model helps jewelers analyze the correct proportions and angles that will best suit the particular stone. The model is usually brought up on a computer which measures the stone's brightness, fire, and scintillation.
The best type of cuts is the ideal cut, which assures that the stone will reflect virtually all the light that enters it. A very good cut reflects almost as much light as the ideal cut and costs less. A good cut reflects most of the light that enters the diamond but is much cheaper than the good cut. A fair cut can still represent a good diamond but it probably wont shine nearly as brilliantly as the good cut. A poor cut is the lowest on the scale and represents stones that do not reflect light in a way that would enhance their brilliance. Many good jewelers will not carry poor cut diamonds. For a good value, select diamonds with a cut grade of good or very good.