Cut is the only human contribution to the diamond’s beauty; however, it is one of the most important factors.  The term “cut” can mean many things.  In the jewelry industry is used to describe the shape, cut style, proportions and finish of a diamond.  Diamonds can be cut into almost any shape.  The most popular shapes are pictured below.

GIA’s diamond cut grade predicts levels of brightness, fire, and scintillation, which indicate how well a diamond’s proportions work together to return white and colored light to the observer.  Face-up appearance, design and craftsmanship are critical to a diamond’s overall cut quality.  Weight ratio, durability, polish and symmetry are all included in GIA’s Diamond Cut Grading System.

How a diamond handles light -

1. When a diamond is cut to good proportions, light enters the stone and is reflected from one facet to another and then dispersed out through the top of the stone.
2. If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion.
3. If the cut is too shallow, light escapes through the pavilion before it can be reflected, thus reducing brilliancy.