Round Cut Diamond Size Chart (MM)

Wondering what a 1 carat round diamond looks link on a hand? Our round diamond size chart will help you convert millimeter (mm) size to carat size for round cut diamonds.

Round Cut Diamond Size Chart (MM)

Round MM Size Round Carat Weight
4 mm. 0.25 ct.
5.0 mm. 0.50 ct.
5.75 mm. 0.75 ct.
6.5 mm. 1.00 ct.
6.8 mm. 1.25 ct.
7.3 mm. 1.50 ct.
7.75 mm. 1.75 ct.
8 mm. 2.00 ct.
8.7 mm. 2.50 ct.
9.1 mm. 3.00 ct.
9.75 mm. 3.50 ct.
10.25 mm. 4.00 ct.
10.75 mm. 4.50 ct.
11 mm. 5.00 ct.
Round Size Chart
Round MM Size Round Carat Weight
0.8 mm. 0.0025 ct.
1 mm. 0.005 ct.
1.1 mm. 0.0067 ct.
1.2 mm. 0.009 ct.
1.25 mm. 0.01 ct.
1.3 mm. 0.01 ct.
1.5 mm. 0.015 ct.
1.75 mm. 0.02 ct.
1.8 mm. 0.025 ct.
2 mm. 0.03 ct.
2.2 mm. 0.04 ct.
2.5 mm. 0.06 ct.
2.75 mm. 0.08 ct.
3 mm. 0.10 ct.
3.25 mm. 0.14 ct.
3.5 mm. 0.17 ct.
3.75 mm. 0.21 ct.
4 mm. 0.25 ct.
4.25 mm. 0.28 ct.
4.5 mm. 0.36 ct.
4.75 mm. 0.44 ct.
5.0 mm. 0.50 ct.
5.25 mm. 0.56 ct.
5.5 mm. 0.66 ct.
5.75 mm. 0.75 ct.
6 mm. 0.84 ct.
6.25 mm. 0.93 ct.
6.5 mm. 1.00 ct.
6.8 mm. 1.25 ct.
Round MM Size Round Carat Weight
7 mm. 1.30 ct.
7.3 mm. 1.50 ct.
7.5 mm. 1.67 ct.
7.75 mm. 1.75 ct.
8 mm. 2.00 ct.
8.25 mm. 2.11 ct.
8.5 mm. 2.43 ct.
8.7 mm. 2.50 ct.
9 mm. 2.75 ct.
9.1 mm. 3.00 ct.
9.5 mm. 3.35 ct.
9.75 mm. 3.50 ct.
10 mm. 3.87 ct.
10.25 mm. 4.00 ct.
10.5 mm. 4.41 ct.
10.75 mm. 4.50 ct.
11 mm. 5.00 ct.
11.25 mm. 5.49 ct.
11.5 mm. 5.85 ct.
12 mm. 6.84 ct.
12.25 mm. 7.26 ct.
12.5 mm. 7.36 ct.
12.75 mm. 7.52 ct.
13 mm. 8.51 ct.
13.5 mm. 9.53 ct.
14 mm. 10.49 ct.
15 mm. 12.89 ct.
16 mm. 16.06 ct.

Princess

Cushion

Oval

Emerald

Heart

Round

Pear

Asscher

Radiant

Marquise

FAQs

Diamond size is measured by carat weight, a unit equal to 0.2 grams. However, size is more accurately and indeed defined by its dimensions, such as length, width, and depth in millimeters. A diamond's diameter (top of the diamond) can indicate its apparent size (especially when comparing two like diamonds).

No, other factors such as cut, shape, and setting can affect a diamond's size. A well-cut diamond can appear more significant than its actual carat weight suggests, while a poorly cut diamond may look more petite.

Yes, some shapes like the oval, marquise, and pear can appear larger per carat than more compact shapes like round or princess cuts. This is due to the elongated shape and larger surface area.

Halo diamond settings surrounding the center diamond with smaller diamonds can make the central stone appear more prominent. Bezel and prong settings can also affect how the diamond's size is perceived. Lastly, setting a diamond in a petite or skinny band can help make your diamond appear larger.

Carat weight refers to the weight of a single diamond, while total carat weight (TCW) includes the combined weight of all the diamonds in a piece of jewelry, such as a ring with a center diamond and side stones.

Generally, the price of a diamond increases exponentially with its size, assuming that all other quality factors (cut, color, and clarity) remain constant. Larger diamonds are rarer and, therefore, more expensive.

Yes, cut quality and shape can make two diamonds of the same carat weight look different in size. A deep-cut diamond may carry more weight "hidden" in the depth, making it look smaller when viewed from above.

This largely depends on personal preference. Some people prioritize size and are willing to compromise on quality, while others prefer a smaller, high-quality diamond with better brilliance and fire. Finding the right balance that suits your taste and budget is essential.

It's crucial to look at the dimensions (length, width, depth) provided and not just the carat weight. Many websites offer actual size views or size comparison tools. Additionally, consider asking for images or videos that show the diamond next to an everyday object for scale.

Large diamonds are more likely to be scrutinized for ethical sourcing due to their higher value. Make sure to inquire about the origin of the diamond and whether it is conflict-free. Some people opt for lab-grown diamonds as a more ethical choice, especially for larger stones.