The Gemological Institute of America established an international language of communicating the quality of diamonds amongst dealers from all over the world. This mode of quality grading is called the "4 C's," which consist of four factors including color, cut, clarity, and carat weight. The basic colors of a diamond range from D-Z (D being the most colorless and expensive, to Z, containing the most yellow or brown color). Cut pertains to the way the diamond is faceted in a particular style. The image shows the most desired cuts in the world. The clarity factor consists of the degree of clarity characteristics the diamond may contain (refer to the chart at the left). Finally, there is carat weight, which measures the weight of the stone. Typically, in an engagement ring for example, one to two and a half carats is the most desired and worn.