Because diamonds are so valuable, it's essential to have a universal grading system for comparing their quality. Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. In the 1940s and '50s, GIA created the first, and now globally accepted standard for describing diamonds: The 4Cs. GIA developed the 4Cs and the GIA International Diamond Grading System to objectively compare and evaluate diamonds. The four characteristics that determine the value of a diamond are Color, Clarity, Carat weight, and Cut. Keep in mind that a single large diamond is more expensive than several smaller stones with the same qualities. This is due to the fact that larger diamonds are harder to find.
The creation of the diamond 4Cs meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they were about to purchase. Today, the 4Cs of diamond quality is the universal method for assessing the quality of any diamond, anywhere in the world.