Carat is a calculation of the weight of a diamond, not size, and not a size measurement at all. A carat is equivalent to 0.2 grams, which can also be expressed as 200 milligrams. The term “carat size” is rather misleading because the weight of a diamond in carats does not precisely indicate how large or small the stone is, despite the fact that there is a correlation between the two.

The price of a diamond grows with its carat weight. This is due to the fact that larger diamonds are both rarer and more coveted than smaller diamonds. However, two diamonds having the same carat weight can have significantly different values (and prices) depending on the color, clarity, and cut, which are the other three components of the diamond grading system known as the 4 C’s.
Diamond carat sizes

The Diamond Carat Weight and Diameter Correlation

Now, it should not come as a mystery that the carat weight of a diamond and the diameter of a diamond has an evident one-to-one relationship with each other. It is mathematically impossible for a diamond that weighs 0.05 carats to have a larger surface area than a diamond that weighs 1 carat.

However, because the quality of the cut can differ quite a little from one stone to another, the range of feasible diameters for a particular carat weight can cover a wide variety of sizes.

Diamond Carat Size and Rarity

The greater the size of the diamond, the higher the price per carat will be. To put it another way, the increase in cost per carat rises significantly with each “magic number.” For instance, the price difference between a diamond that is 4 carats and one that is 3 carats is significantly larger than the price difference between a 3-carat diamond and a 2-carat diamond. The larger diamonds are far more difficult to come by than the smaller ones. Therefore, the price of the diamond increases proportionally with its size.


An electronic microbalance is what is used to determine how much a diamond weighs. Even though the weight is calculated to the fifth decimal point, the weight is only ever published to two decimal places, also known as the hundredths of a carat. This is a key aspect to keep in mind, as it is the case that you will always find the weight stated only in two decimal places. Now, rounding off a diamond’s carat size does not adhere to the same criteria as mathematical approximations. The GIA, which is the certification organization for diamonds all around the world, only shifts a digit to the next hundredth place if the digit on the thousandth place is a 9. Because of this, a diamond with a weight of 1.458 carats would be described as having a weight of 1.45 carats, while a diamond with a weight of 1.459 carats would have its weight stated as being 1.46 carats.


There is no assurance that the diamond will be of a larger size simply because it has a higher carat weight. It is dependent on the cut that the diamond already possesses as well as the expertise of the person who cut the diamond. A “Triple X” diamond that has been cut and polished to perfection may give the appearance of being smaller than an imperfectly cut diamond of higher carat weight. However, the former will have a better light play than the latter. It all depends on the diamond’s cut, which is why the grade of the diamond’s cut is more important than the carat weight when it comes to assessing its value.

Diamond Carat Weight chart

Buying Tips for Diamond Carat Weight

The following pointers are to be remembered before purchasing diamonds based on carat weight:

  1. Choose a carat weight to suit the wearer’s fingers. When purchasing diamond jewelry, it is important to select a diamond with a carat weight that is appropriate for the wearer’s fingers. If you have thicker fingers, you shouldn’t choose a lower carat size because it won’t look right on them. On the other hand, opting for a ring with a bigger carat weight when you have narrower fingers will make the ring appear more noticeable.
  2. Consider the diamond size and your budget. Do not fall into the trap of thinking that a larger diamond must have a higher carat weight. You should allocate your budget based not just on the carat size of the diamond but also on its other attributes. If the cut, color, and clarity of a huge diamond are subpar, it is unlikely that it will appear as nice as a stone of a lesser carat weight but greater grade.

Magic Sizes

Some weights, like the carat, the half carat, and the three-quarter carat, are referred to as “magic sizes.” Visually, a diamond that weighs 0.99 carats and one that weighs a whole carat are virtually indistinguishable from one another. However, there may be large disparities in the prices of the two options.

Final Thoughts

When looking to buy a diamond, one of the essential aspects to consider is the carat weight of the stone. Carat weight, which is one of the 4 C’s and determining factors that go into establishing the price of a diamond, is by far the most important of these factors. This is due to the fact that it is the method that arrives at the most objective estimate of a diamond’s genuine worth.

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