Every diamond is unique and there are a variety of factors affecting the price, quality, and brilliance of a diamond. GIA has graded some of the world’s famous diamonds using 4C grading system. They examine each diamond under controlled lighting and viewing conditions. 4 C grading system represents the main characteristics of the beauty and structure of a diamond. Color, Clarity, Cut and Carat of a diamond constitutes the C’s in the 4 C grading system.
Diamond Color Grading
In diamond color grading, color of the diamond is graded in a standardized normal viewing environment against predefined color masters. Here, two color graders have to enter their evaluations independently into the system. Based on their grades, weight and quality of the diamond, it will be sent for other graders to mark their grading. GIA color grades diamonds from D to Z, where D is colorless and Z is slight brown or yellow tint.
Diamond Clarity Grading
Clarity of a diamond is graded with 10x magnification under standard viewing conditions. Primary recommendation for clarity is to ensure that the diamond is eye clean. First grader should carefully examine the clarity of a diamond and should look for evidences of fracture filling or laser drilling. Then a minimum of two graders have to examine diamond’s symmetry, polish and clarity. A diagram representing shapes and faceting styles plotted with clarity characteristics should also be prepared.
Diamond Cut Grading
Diamond cut refers to the quality of diamond’s angles, proportions, symmetry, finishing details etc. These factors determine the sparkling effect and shape of a diamond. GIA grades on diamond cut are ideal, excellent, very good, good, fair and poor. An ideal cut is referred as one with ideal angles, proportions and symmetry. Round, brilliant and princess cut are ideal ones. Diamond cut is characterized as the most important feature and it should be given higher priority than other C’s.
Diamond Carat Grading
Carat of a diamond refers to the weight, not its size. One carat is defined as 200 milligrams. For calculating the weight of a diamond, it is weighed using an electronic micro balance. The balance captures the accurate weight of the diamond up to fifth decimal place. Facet angles, proportions, and measurements can be also determined using an optical measuring device. Two diamonds having same carat may differ in size depending on their shape and cut.