Diamond Size - Carat Weight

‘Carat’ is the term used to refer to the weight of a diamond. Diamonds are sold in carats and it is a unit of weight, though it is commonly mistaken as a measurement of diamond size. So, it is not always necessary that, say, a 0.96 carat diamond is smaller than a 1.00 carat diamond. It is important to look at the ‘mm’ measurements of a diamond to understand the diamond size. Also, diamond prices increase exponentially with the increase in weight. So, a 2 carat diamond will be priced much more than twice the price of a 1 carat diamond. Carat is unrelated to the similar sounding 'Karat' which is a measure of gold purity.

1 carat = 0.200 gms (one carat equals 1/200th of one gram)

Another term used for diamond weight is ‘Cents’.

1 carat = 100 cents

So, 0.10 carat is also referred to as 10 cents.

Learn more about diamond carat

Also, a very important thing to note is that with an increase in carat weight, the actual size of the diamond does not increase by the same proportion. So, a 2 carat diamond is much smaller than twice the size of a 1 carat diamond, as illustrated in the diamond carat-size charts below. 


Carat Size Chart For Round Diamonds

The below chart gives the approx diameter measurements in mm/millimeter for different carat weights of a round diamond. This gives a good idea of how big the diamond will be but please note that not all diamonds of, say, 0.20 carat will have 3.80mm diameter. A 0.18 carat round diamond can also have a 3.80 mm diameter and 0.22 carat round diamond also may have a 3.80 mm diameter. This is because diamonds can be cut in various ways. The below diameters are just an indicative measure for different carat weights of a round diamond with 'Excellent' cut grading. 


Round carat weight



Having trouble picking the right diamond carat/size?

It is one of the most common problems when choosing a diamond. Well, worry not, for this great image below will help you in getting a good idea of how big diamonds of different carat weights actually look so you can make your decision. Here, we have compared round diamonds against the standard length of a woman's fingernail. 






Smaller Round Diamonds

 Carat Wgt   mm size 
0.01 1.30
0.015 1.50
0.02 1.70
0.025 1.80
0.03 2.00
0.04 2.20
0.05 2.30
0.08 2.80
0.10 3.00
0.14 3.30
0.18 3.60


Solitaire Diamond Size - Round

Selecting the centre diamond size can be tricky and here is a great image to help you make the best choice. Keep in mind that once the diamond is set in a ring, depending upon the setting, it will look at least 10% bigger. The image below shows how actually big the diamonds will look on a hand.


Round Diamond size on actual hand 


Carat Size Chart For Fancy Shape Diamonds

 Learn more about different diamond shapes and the sizes.







Princess diamond size on actual hand