Carat indicates the weight of the diamond and is what primarily determines the value of the diamond. A 1 carat diamond weighs 0.2 grams. The term Carat comes from the Latin name for the seeds of the carob tree, Keration. In ancient Greece, traders used these seeds to weigh the products they sold.
The seeds of the carob are known for their equal weight; just under 0,2 grams, and therefore they were considered a reliable counterweight. To determine the weight of a diamond, you also sometimes talk about “points”, where 1 point is equal to 0.01 carat, and 100 points is 1 carat.
It is easy to believe that the carat indicates the size of the diamond. But how big the diamond is perceived is depends on many things, not least how the stone is cut and how well the work is done. All diamonds are unique, and all raw diamonds are cut based on its specific conditions. Some diamonds become deeper – with more carats accumulated in the bottom of the diamond, while some diamonds are shallower and thus have a larger diameter.
In other words, two diamonds that both weigh 1 carat can have different diameters. However, a certain symmetry is required for the diamond to be classified as a high-class stone. For example, a flatter brilliant-cut diamond may have a larger diameter but will still be classified as a less valuable stone, since the cut will not be classified as Excellent or Very Good.
The shape of the cut can also affect how the diamond is perceived; a princess cut diamond can in some cases be perceived as larger than a round, brilliant-cut one. At Efva Attling Stockholm, we start from the design of the jewellery and hand-pick diamonds that fits. In other words, we choose diamonds that are identical in diameter, for each design.
In contrary to most things, the diameter of the diamond does not increase linearly with the weight gain. This means that a 2-carat diamond is not twice as big as a 1-carat diamond. Often only a few millimeters differs in diameter between the two weights.
The larger a diamond is, the rarer it is. Only one diamond in 1 million weighs more than 1 carat. This means that the price of diamonds does not increase exponentially, a 2 carats diamond costs much more than two 1 carat diamonds do together. It is also important to remember that it is not only the weight that determines the price of the diamond, the colour, clarity and cut of the stone also affect its value.