Tips and Tricks

Diamond Weight Guide

Shopping for your diamond engagement ring? Here, we will discuss in detail about carat weight, which is one of the most important among the 4C’s (clarity, cut, color, carat weight) quality of a diamond to consider while buying a diamond.

But before we get started, let’s make sure you don't confuse the word ‘carat’ with ‘karat’; karat is a unit that measures the purity of gold and carat by definition means how much a diamond weighs.

Diamond carat: weight defined and its origin

The word ‘Carat’ originates from Ceratonia siliqua, generally known as the Carob Tree. In olden times, prior to the invention of weighing scales, diamond traders matched the weight of a diamond with a seed of the carob tree, interesting right?

The carob seed pod and seeds showing uniformity in size

Thus, carat is a term used to describe the weight of a diamond. They are weighed in metric carats: 1 carat is equal to ⅕ of a gram, or 200mg, about the same weight of a paper clip!

Terminology used to describe diamond’s weight measurement

We know by now that diamonds are weighed in carats. So just like a dollar is divided into 100 pennies, in the same way, carat can be divided into 100 points. Thus, a 75 point diamond weighs 0.75 carats, and this is referred to by a jeweler as a seventy-five pointer. This method of assigning weights allows very accurate measurements to the hundredth decimal place.

Let’s check out different units of measurement related to the weight of a diamond


Small diamond melee in metal bowls

These are small diamonds that weigh less than 0.2 carats. They are used to add that extra glitter to a center stone and bring a magnificent shine to the jewelry.


These are small diamonds, which typically give a diamond ‘ dust-like appearance’ and come in the weight range of 0.009 and 0.021 carats.

How does carat affect a diamond’s price?

A wallet with 100 dollar bills sticking out

According to the diamond industry data, for every million rough diamonds that are mined, there is usually only a single diamond that is large enough to be cut into a single carat diamond. Thus making larger carat weights more difficult to find than the smaller ones and more expensive. However, it is important to note that although carat does have an impact on the price of a diamond, it is not the sole factor that determines a diamond’s price. For example, a diamond can weigh more but if its clarity isn’t good, or if its cut is poor, the price of this diamond will fall considerably.

How does carat affect a diamond's size?

A diamond’s size is quite often interchangeably used with the term carat weight. In actuality, a diamond’s size refers to the dimensions of a diamond along with the measurement of its key portions. Therefore, carat weight of a diamond does not equal the diamond size.

Loose diamonds being weighed on a scale

A weighing scale is used to measure a diamond's weight whereas optical measuring devices are used to measure the proportions, dimensions and angles of the facets of a diamond to determine its size.

How does diamond shape affect carat weight?

Even though some diamond shapes have the same carat weight, they look bigger than the other shapes. The reason is that some diamond shapes, like the oval and marquise, which are slender in shape not only have the same depth percentage as the round but are also extra long.

Similarly, some diamond shapes look smaller than other shapes. For example, a princess cut diamond has deeper depth, that is why this shape looks smaller when compared to a similar carat weight round diamond.

Magic Carat Weight Sizes: what are they?

There are some weights in diamonds that are considered as ‘magic sizes’ - like the half carat (0.50ct), three quarters (0.75ct) and a carat(1.00ct).

You may wonder why they are called the magic sizes? Well, because the price magically jumps up once it gets to 1 carat and other mentioned fractions. And with the desire of people to be able to say that their diamond is ‘a carat’, even though a 0.97 carat with the same mm measurements, still it doesn’t appeal to them like a full carat does.

How to determine a diamond’s carat weight?

Diamonds require a highly accurate reliable weighing scale. They should be in loose form when they are put on the scale to know their accurate carat weight. And for diamonds that are set in jewelry, the jeweler would have to estimate their carat weight approximately by measuring them.

Signing off with the hope that this guide on carat weight will help you to be able to discern and choose diamonds wisely!