What Is Diamond Carat Size?

Before the coming of the carat, gemstone evaluation and standards depended on individual countries, and your geographical location. It wasn’t until 1907 that a standard unit of measuring gemstones, including diamonds, was universally adopted as the carat.

What Is A Carat?

A carat is the standard unit of measuring diamonds, and it equates to 200 milligrams. Experts subdivide the carat into 100 points to achieve precise diamond measurements, up to the hundredth decimal point. This makes it possible to describe diamonds less than a carat, such as 0.25 (twenty-five pointer).

Diamond prices increase with carat weight since larger diamonds are extremely rare to find. But two diamonds of equal carat weight may come at different prices and values when the other three factors of the diamond 4Cs (cut, clarity and color) come into play.

Diamond Carat vs Size

You may often confuse carat weight with visual size when shopping for the perfect diamond for your wedding or engagement ring. Carat weight doesn’t necessarily correlate with diamond size because several factors go into determining the weight of the stone. These factors include the shape, formulation of the diamond, and its density. It’s not uncommon to find a stone with less carat weight but visibly bigger than a higher carat diamond.

How Big Is A 1 Carat Diamond?

Knowledge of the size of a one-carat diamond may help make things a bit clear. A one-carat round diamond stone measures about 6.5 mm. but this size may vary depending on the shape of the stone, and how well it’s cut. The variance ranges from 6.11 mm to 6.53 mm, and you can attribute it to the type of cut.

How Does Diamond Shape Affect Carat Size?

Some diamond shapes may appear much bigger than others even when they carry the same carat weight. Ovals and marquise have the same depth as rounds, but the benefit of extra length, hence, they are bigger.


When shopping for the best diamond for your engagement or wedding ring, you need a sufficient understanding of carat weight. The Diamond Guys can help you navigate this challenging task to get you the right diamond. Contact us today to learn more.