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How Big is a 1 Carat Diamond? (Diamond Size Chart)

A Diamond Size & Carat Weight Chart By Lead Gemologist Erica Hirsch, GIA GG

Carat, as you might already know, is a measure of weight, not size. Similar to people, each diamond wears it’s weight a little different. You might hear a diamond dealer use the word “spread” when referring to a diamond’s size. A “spready” diamond is one that looks bigger then it is. This can be hard to tell in photos which is why we’ve put together a handy diamond size chart to show the differences in size between the various diamond cuts.

Pear and oval shaped diamonds are wider and more flat, whereas round brilliants and Asscher cuts tend to run deeper. If you’re looking for the most carat for your dollar, look no further then a Marquise. This flat, generous diamond shape not only elongates the finger but looks nearly twice as big as it’s round cousin.

If you’re flexible on shape, this can be a great way to get a diamond that looks bigger without costing more, and while historically the round brilliant has reigned supreme, we think the other cuts are just as dazzling. Use our diamond size chart to understand how different diamonds shapes compare.


A visual reference for round, oval, cushion, emerald, pear, Asscher and marquise cut diamonds

A diamond size chart depicting round, emerald, asscher, marquise, cushion, pear and oval diamonds at .5,1,1.5,2 and 3 carats.


And other industry secrets

Unfortunately, carat weight on its own can be misleading. Picture a trusty, yellow, #2 pencil.  That’s the one. It has a round, pink eraser on top that’s 7mm in diameter. 7mm is also the diameter of a 1.25 carat round brilliant diamond. For a visual reference, check out the diamond size chart below.

That might be more or less diamond than you expected. That’s partly because we price diamonds by carat weight, not their dimensions. The size a diamond appears is determined by both its carat and its shape. Diamonds of the same weight, but in different shapes, will appear to be different sizes.

When choosing a diamond shape, you might end up with a much larger, or smaller diamond than you were expecting.

As an example, a .7 carat oval diamond can look as large as a 2 carat Asscher diamond.

Four oval cut diamonds on a hand

With your little pink friend as your guide, explore how the other cuts and shapes stack up in size and cost and of course, carat weight with this handy diamond size chart.

Diamond size chart


Every great ring starts with a great setting, but picking a setting out online is hard — or at least it used to be. At Frank Darling, all our engagement ring settings are available for free home try-on. It’s like the internet, but in real life.

Take the quiz to get started, and select your favorite four rings. We’ll send you sterling silver size seven replicas set with 1 carat CZ stones.

So, what are you waiting for? Let’s get this party started.