When a diamond is cut to good proportion, light is reflected internally from one facet to another and dispersed through the top of the diamond. Diamonds can be cut to many different shapes, but it is the precise proportions to which the facets are cut that allow it to capture light and release its brilliance and fire.
Most diamonds used in jewelry appear white. There are, however, subtle differences in color, and the closer a diamond is to being colorless, the more valuable it will be.
Most diamonds contain inclusions such as mineral traces formed during the crystallization process. This is part of what makes each diamond unique. The number, the size and position of the inclusions determine the clarity of a diamond and affect its value.
This is the unit of weight for diamonds. A carat is divided into 100 smaller units called "points". So, for example, 3/4 of a carat is 0.74 points.