Most people link the Carat Weight to the size of the diamond. However, Carat is a unit of measurement of weight used to weigh a diamond. The actual size of the diamond is always measured in mm.
To understand carat weight properly, let us look at how it compares to normally units of weight.

1 Carat = 0.200 grams or 200 milligrams (yes, it’s that light).

As I mentioned in my Diamond Formationblog, it takes extremely high temperature and pressure for a diamond to be formed from carbon molecules. In fact, the chances of a diamond being formed and successfully making it to the surface of the earth are much lower than winning a lottery. Hundreds of kilometers underneath the surface of the earth, it is very unlikely that these extreme conditions remain stable and favorable for a long period of time for the growth of a large diamond. Therefore, it is very rare to find a large sized rough diamond.

No doubt, only a few monster-sized rough diamonds have been mined through history – the most famous being the 3104 carat Cullinan diamond. However, majority of the diamonds mined today are quite small in size. Here’s an interesting statistic – it requires close to one million diamonds to be mined before a one carat stone happens to be found.

Interesting Trivia: The word “Carat” comes from the ancient practice of using “Carob” seeds for measuring weight. The fact that these identical seeds were perfect in size and weight compared to one another made them ideal as a unit of measurement.

Due to this shortage of bigger diamonds, carat weight has always played a significant role in determining the price and the value of diamonds. The bigger the diamond, the rarer it is to be found. And hence the bigger the stone, the more expensive it is per carat. The price of a diamond per carat weight increases exponentially with size. For example, while a one-carat stone can fetch anywhere from $6,000 to $15,000, a sparkler of 3-4 carats could demand a price of more than $18,000 per carat depending on its color and clarity.

It is also interesting to note that as the carat weight of a diamond increases, the relative size does not increase in the same proportion. For example, the diameter of a one carat diamond is approximately 6.4 mm. However, the diameter of a two carat diamond is only 8.1 mm.

Hard Fact: Gold and diamonds, the two major components in precious jewelry, use Karat and Carat, respectively, as a unit of a measurement.  Carat with a “C” applies to diamonds and it indicates the weight of the diamond. Karat, with a “K”, on the other hand, refers to the purity or fineness of gold.

Interesting Trivia: Most people, outside the diamond industry, believe that the Cut of a diamond refers to the shape of a diamond. However, a trained gemologist refers to specific cutting parameters that bring a particular shape to life with highest fire, brilliance and scintillation.

Based on classifications and nomenclatures followed by the diamond industry around the world, the Cut of a diamond is divided into five categories.

1. Excellent Cut:The design of this cut is such that it ensures every shard of light entering the diamond is reflected multiple times and in all directions, thereby literally setting the stone afire from within. Achieving the Excellent Cut requires exceptional expertise and craftsmanship.Excellent cut diamonds show equal dark and light shades, creating an impression of play of shadows and light.

2. Very Good Cut:Very Good Cut diamonds have slightly more flexible cutting parameters than Excellent Cut. When skilled craftsmen attempt to retain higher carat weight by slightlycompromising onthe light performance, the Cut becomes Very Good. Diamonds with Very Good Cut still show good deal of sparkle, brilliance and fire, but their price per carat is much lower than that of an Excellent Cut diamond.

3. Good Cut:Just like the Very Good Cut, Good Cut diamonds are created by sacrificing quality of the cut over carat weight of a diamond. Most of the size proportions of diamonds in this cut are quite broader than those of the Excellent or Very Good Cut as the target is to get maximum stone size rather than focusing on the light performance. Such diamonds are ideal for the more budget conscious buyers who want to have a pretty stone that is larger in size.

4. Fair Cut: A cut that is almost at the bottom of the grading spectrum in terms of quality and preference. The only aim of those working with this cut is to get the maximum possible carat weight out of the rough diamond. There is very little consideration given to the color or clarity of the stone. The value of Fair Cut diamonds is based largely on their carat weight.

5. Poor Cut: The lowest of cuts in diamonds. These diamonds perform very poorly when it comes to the light performance inside the diamond based on internal reflection and refraction. They are just stones that have been processed to look big. As the cut is not optimized, there can be multiple inner impurities as well as outer surface defects. For those only looking to own a gem that is called a diamond without any other specific considerations, these are the diamonds to buy.