How Diamonds are Graded
If you’re shopping for a diamond, you probably have a lot of questions like, how can I be sure that what I’m purchasing is a real natural diamond, how do I know if the diamond has been treated. The key to understanding a diamond and its value is to understand the four attributes that all diamonds share, color, clarity, cut, and carat weight, also known as the 4 C’s. The Gemological Institute of America or GIA developed the 4 C’s in order to create a universal language when it came to the difficult task of determining diamond quality. Established in 1931, non-profit GIA is the largest and most respective institute of gemological research and learning in the world. GIA created not only the 4 C’s but also the international diamond grading system, the grading standard used worldwide. Let’s follow a diamond through the steps in the GIA grading process and see how it’s evaluated. Scientific precision is critical as expert gemologists examine each diamond under tightly controlled lighting and viewing conditions. Each diamond travels through the lab in a non-descript case to be sure that it is graded consistently and objectively. First, it is tested to determine whether the diamond is natural or lab-grown. If the diamond were synthetic, it would be pulled out of the queue and subjected to a separate procedure. Next, it’s under the 4 C’s. The first C is color. When it comes to diamonds, the less color the higher the grade. The GIA color scale classifies diamonds from D-colorless to Z-light yellow or brown. At the GIA lab, a color grade is determined by comparing each diamond to a master set of diamonds that represent the color grades on the GIA scale. The second C is clarity. The GIA clarity scale included 11 clarity grades ranging from flawless to I3. Flawless indicates that there are no inclusions or blemishes visible at ten times magnification. A grade of I3 is for diamonds with inclusions that are obvious to the naked eye. A 10 times magnification look in a microscope are used to see and plot the inclusions. Since no two diamonds are exactly alike, this unique plot helps identify a particular stone. Graders also look to see if there is any evidence that our diamond was treated to improve its clarity. The third C is cut. The GIA cut scale is used for round brilliant cut diamonds and consists of 5grades ranging from excellent to poor. You may think of cut as the shape of a diamond like square cut or round. However, there is much more to cut than the basic shape. How a diamond is cut and polished directly affects the amount of sparkle and brilliance that comes off the stone. Each diamond is placed in a highly precise measuring device that rotates the stone 360 degrees to optically capture hundreds of measurements and facet angles. After 15 years of research, GIA scientist developed a comprehensive system that factors the diamond’s proportions as well as its cubic size, girdle thickness, polish and symmetry descriptions, and generates a GIA cut grade. The fourth C is carat weight. One carat equals 200 milligrams of one fifth of a gram in weight. At the GIA lab, each diamond is placed in a sealed chamber and weighed in an extremely precise electronic scale to the fifth decimal place. The diamond’s 4 C’s along with the wealth of additional information appears on its GIA grading report. A GIA report is the most technologically advanced diamond evaluation possible. It provides a unique blueprint of a diamond’s attribute and a permanent record of its quality. As an added security feature, diamonds graded at GIA can be microscopically inscribed along the girdle with their unique GIA report number. The act of choosing your diamond should be exciting and enjoyable. Just keep all the 4 C’s in mind, color, clarity, cut, and carat weight. And be sure to always ask your jeweler for a GIA report, your ultimate assurance of your diamond’s quality because at GIA grading report is the difference between wondering and knowing.