Carat is the term used when referring to the weight of a diamond. The small and uniform carob seeds served as perfect counter weight to the diamond prior to the twentieth century. The term “carat” that we used today has its origin in the word “carob”.
A carat weight of a diamond is proportional to its size. As much as 2/3 of the total carat weight can be lost when rough diamonds are cut and polished into finished diamonds. Two one-carat diamonds of the same quality can be less expensive than a single two carat diamond because larger rough gems of high quality are found less frequently.
In Europe , one carat or less in weight diamonds represent the majority of diamonds used in jewelry and sold as loose diamonds. The diamond in the average engagement ring sold in Europe is less than 0.50 carat in weight.
The weight of a diamond will increase much faster than the actual “face-up” diameter. For example, an ideal cut one-carat diamond measures approximately 6.5mm in width but a diamond twice its weight measures only 8.2mm. That is only a 30% increase in the “face-up” diameter. The graphic below illustrates this point.
There is no direct answer to the question since it depends on several factors. When looking at a diamond engagement ring, you only see the visible surface area on the top of the diamond and this doesn’t allow you to get a strong sense of the diamond in terms of the carats. Your preferences and budget are what determines what carat weight is right for you. It is advisable to focus on the diamond cut and diameter rather than the weight, even though the weight is clearly an important factor since it influences cost quite a bit.