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 1/200^th 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. 

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

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.

Carat Size Chart For Fancy Shape Diamonds

 Learn more about different diamond shapes and the sizes.