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  • Carat refers to a diamond´s weight, however, it does not necessarily reflect a diamond´s size
  • Carat weight is highly influenced by the diamond´s cut and shape
  • A diamond´s carat number has a psychological impact on price

Diamond weight

Carat represents the weight of a diamond. One carat weighs 0.2 grams and therefore one gram equals a 5 carat diamond. The word originates from the carob trees´seeds that were used in ancient times as weight measurement units due to their assumed uniformity. In the trade one carat is divided into 100 points which means 0.25 carat diamond is also called a 25-points-diamond.

Carat weight, cut and the size

Even though most people relate carat weight to diamonds, it is important to stress the difference between a diamond´s weight and its size: Just like a person´s weight does not necessarily correlate with the height, the mere carat weight does not accurately describe the size of the diamond. In fct, the diameter and cut determine the size of a diamond to a great deal.

Consider the following illustrations:

While one diamond has a bigger diameter and appears larger looking from above, the other retains most of its weight in the pavilion, the lower part of the stone, and therefore seems smaller even though they both have the same weight. Usually a “flat” and seemingly bigger diamond compromises on cut and therefore is lacking brilliance and fire. The same is true for “heavy” diamonds with large pavilion depths.

A 1.00 carat diamond can have a diameter in between approximately 5.75 mm to about 6.9 mm. Most round brilliants with cut grade “excellent” are in between 6.3 mm to 6.6 mm in diameter and most people consider a diameter of 6.4 mm to 6.5 mm most desirable. We recommend you to always take the cut into consideration when choosing a diamond. If you have further questions on this topic our experts will gladly help you.
Measuring a diamond´s diameter with a gemstone gauge

Carat weight and rarity

Diamonds are cut to retain weight because every loss of the expensive rough material is a loss in money. That is also the reason why not every diamond is cut to ideal proportions. The traditional round brilliant cut for example costs about 60% of the rough material during the cutting and polishing process. Another important factor is rarity: The larger the diamond, the rarer it is. This rarity rises exponentially the higher the quality of the diamond. Finding a two carat diamond is already rare. However, finding one of this size without inclusions is very rare. And actually finding a two carat diamond that has no inclusions and a high color grade in addition to that is extremely rare and difficult to get. That explains why a two carat stone does not only cost And Wichtig ist auch die Seltenheit: Je größer der Diamant, desto seltener. Diese Seltenheit steigert sich exponentiell, umso höher die Güte (Farbe und Reinheit) des gewünschten Edelsteines. Ein Zweikaräter ist bereits schwer zu finden. Die Chance einen lupenreinen Stein in dieser Größe zu finden ist noch geringer. Wenn man dann noch einen hohen Farbgrad wünscht wird leicht verständlich, warum ein Zweikaräter nicht nur doppelt so viel kostet wie ein Einkaräter in vergleichbarer Qualität.

Carat weight is always measured to the second decimal place: