4 Cs Of Diamond Quality It’s no secret that diamonds are one of the most treasured materials in the world; formed hundreds of miles under the earth’s surface over the space of billions of years, before being intricately cut and polished by diamond specialists. You can understand why these remarkable stones are so precious. But how can you tell the difference between a low-quality diamond and a high-quality one? Many people assume that the higher carat a diamond is, the more expensive it will be. In a lot of cases this is true, but in actual fact assessing the carat of a diamond is only a small step in the valuation process. First created by the Gemological Institute of America (GIA), the ‘4 C’s of diamond quality’ is a process that is recognised by diamond experts around the world. Each of these 4 C’s have a unique grading system to help buyers understand what quality of diamond they’re paying for. Whilst it can take years of education and practice to understand the 4 C’s thoroughly enough to grade a diamond accurately, it always helps to have a basic understanding of this process when buying diamond jewellery.  


Often considered the most important of the 4 C’s, the cut of a diamond is judged by how well its facets interact with light; in other words, how much the stone will sparkle. A perfectly cut diamond is made in a way that allows the diamond to reflect light back out of the top of the stone. If a diamond is cut in a way that makes it too shallow or too deep then it will lead to light leaking out of the side or bottom, resulting in a dull appearance. The cut of a diamond is graded on five different categories: Excellent, Very Good, Good, Fair and Poor.  


The colour of a diamond plays a huge role in how much it costs, with the most expensive diamonds appearing totally colourless. The GIA uses a lettered grading system ranging from D to Z, with D being the highest quality of diamond. Many of the differentiations between each grade will be invisible to the naked eye, therefore the colour of a diamond needs to be measured in a controlled environment using a very precise methodology. This lettered grading system is also split into various different categories; Colourless (D to F), Near Colourless (G to J), Faint (K to M), Very Light (N to R) and Light (S to Z).  


The carat of a diamond is one of the most widely-known elements of the 4 C’s. This grading system is often misinterpreted as referring to the size of a diamond, but ‘carat’ actually refers to the weight of a diamond. One metric carat is officially known to weigh 200 milligrams (or 0.2 grams). Whilst many jewellers market their diamond jewellery by carat, for example “1 Carat Diamond Engagement Ring”, it’s important to remember that the carat of a diamond is only one of four factors that jewellers consider when pricing a stone. It’s very possible for a 0.5 carat diamond to cost more than a 1 carat diamond.  


The final element of the 4 C’s of diamond quality is clarity. When natural diamonds are formed, they can often adopt various imperfections both internally (inclusions) and externally (blemishes). It’s very rare to find a diamond that is completely perfect but generally the fewer inclusions and blemishes on a stone, the higher its price will be. The clarity grading system is split into six categories, with 11 exact measurements: Flawless (FL), Internally Flawless (IF), Very, Very Slightly Included (VVS1 & VVS2), Very Slightly Included (VS1 & VS2), Slightly Included (SI1 & SI2) and Included (I1, I2 & I3).   As one of the most widely-accepted ways of valuing diamonds, it really does help to understand what the 4 C’s mean before buying diamond jewellery. Why not browse our full blog for more articles like this?