Diamond Size Chart (11 Types)

Contrary to popular belief, carat doesn’t refer to the diamond size but its weight. Besides this unit, the gem’s visual size and price also depend on its shape and cut grade. The best option to precisely define precious gem size is using a diamond size chart that can significantly differ considering its shape. Let’s see.

The Diamond Size Chart

Whether you want to sell or buy a diamond, it is essential to learn how to measure its size and estimate its weight in carats.

Diamond carat per size in millimeter
Diamond	Carat
Shape	0.25	0.5	0.75	1	1.5	2	3	4	5
	Size in mm
Round	4.1	5.1	5.8	6.4	7.4	8.1	9.3	10.2	11
Princess	3.5	4.4	5	5.5	6.4	7	8	9	9.5
Radiant	3.5 x 3	5 x 4.5	5.5 x 5	6 x 5.5	7 x 6	7.5 x 7	8.5 x 7.5	9.5 x 8.5	10 x 9
Asscher	3.7	4.4	5	5.5	6.4	7	8.1	9	9.6
Cushion	4 x 3.5	5 x 4.5	6 x 5	6.5 x 5.5	7.5 x 6.5	8 x 7	9 x 8	10 x 8.5	10.5 x 9
Heart	4.2	5.4	6	6.7	7.6	8.3	9.5	10.3	11
Emerald	4.5 x 3	5.5 x 4	6 x 4.5	6.5 x 5	7.5 x 5.5	8.5 x 6	9.5 x 7	10.5 x 7.5	11.5 x 8.5
Trillion	4.9	6.1	7	7.7	8.9	9.8	11.2	12.3	13.2
Oval	5 x 3	6.4	7.5 x 5.5	8 x 5.5	9 x 6	10.5 x 7	11.5 x 7.5	13 x 8.5	14 x 9.5
Pear	5.5 x 3.5	7 x 4.5	8 x 5	8.5 x 5.5	10 x 6.5	10.5 x 7	12.5 x 8	13.5 x 9	15 x 10
Marquise	6.5 x 3.3	8.5 x 4	9.5 x 4.5	10.5 x 5	12 x 6	13 x 6.5	14 x 7	16 x 8	17 x 8.5

 

Round diamond

A traditional round diamond is a trendy circularly shaped gem that works well in almost all settings. Its faceted bottom makes it vivid, while the larger flat table means the higher carat weight.

Round diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
0.8 mm	0.0025	3.5 mm	0.17	7.3 mm	1.5	10.83 mm	4.75
1 mm	0.005	3.75 mm	0.21	7.5 mm	1.67	11.1 mm	5
1.15 mm	0.0067	4 mm	0.25	7.75 mm	1.75	11.25 mm	5.49
1.2 mm	0.0075	4.25 mm	0.28	8.1 mm	2	11.5 mm	5.85
1.25 mm	0.01	4.5 mm	0.36	8.25 mm	2.11	11.75	5.9
1.3 mm	0.01	4.75 mm	0.44	8.5 mm	2.25	12 mm	6.84
1.5 mm	0.015	5.1 mm	0.5	8.9 mm	2.5	12.25 mm	7.26
1.75 mm	0.02	5.25 mm	0.56	9 mm	2.75	12.5 mm	7.36
1.8 mm	0.025	5.5 mm	0.66	9.3 mm	3	12.75 mm	7.52
2 mm	0.03	5.8 mm	0.75	9.5 mm	3.25	13 mm	8.51
2.25 mm	0.04	6 mm	0.84	9.75 mm	3.5	13.5 mm	9.53
2.5 mm	0.06	6.25 mm	0.93	10.1 mm	4	14 mm	10.49
2.75 mm	0.08	6.4 mm	1	10.25 mm	4.16	15 mm	12.89
3 mm	0.11	6.9 mm	1.25	10.43 mm	4.25	16 mm	16.06
3.25 mm	0.14	7 mm	1.28	10.63 mm	4.5	18 mm	18.8

 

Princess diamond

The princess is a square or rectangular diamond that is a modern alternative to a typical round cut. Its measurement entirely depends on the stone length, and the largest commercial 9.52 carat pieces are 12 mm long.

Princess diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
1.5 mm	0.015	3 mm	0.18	4.5 mm	0.5	6 mm	1.25
1.75 mm	0.03	3.5 mm	0.29	5 mm	0.75	6.5 mm	1.5
2 mm	0.06	4 mm	0.39	5.5 mm	1	7 mm	2

 

Cushion diamond

Cushion cuts are square or rectangular with rounded edges. They are often understated but are a stylish option for colored diamonds nowadays. The biggest gems are those 15 mm long with 12.89 carats.

Cushion diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
4 mm	0.25	5.5 mm	1	7.5 mm	2.5	9 mm	4.12
4.9 mm	0.5	6.5 mm	1.5	8 mm	3	9.5 mm	5.09
5.25 mm	0.75	7 mm	2	8.5 mm	3.5	10 mm	5.62

 

Emerald diamond

It is a rectangular stone that can appear larger thanks to the way of faceting. It has no impressive depth but is highly shiny and sparkle. You can find vintage and modern rings with this diamond cut that sizes up to 17 x 13 mm and 16.5 carats.

Emerald diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
3 x 2 mm	0.1	6 x 4 mm	0.5	7.3 x 5.3 mm	1.25	8.5 x 6.5 mm	2
4 x 2 mm	0.15	6.5 x 4.5 mm	0.75	7.5 x 5.5  mm	1.5	9 x 7 mm	2.5
4 x 3 mm	0.2	7 x 5 mm	1	8 x 6 mm	1.75	10 x 7.5 mm	3

 

Oval diamond

This stunning cut stone is not a mainstream choice, but its advantage is that it can look larger even when it weighs less. You always need to check both the diamond’s length and width to get precise measurements.

Oval diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
5 x 3 mm	0.21	7.7 x 5.7 mm	1	12 x 8 mm	3	15 x 12 mm	8.76
5 x 4 mm	0.35	8 x 6 mm	1.25	11 x 9 mm	3.85	16 x 12 mm	9.32
6 x 4 mm	0.5	8.5 x 6.5 mm	1.5	12 x 10 mm	5.05	16 x 14 mm	11.88
6 x 5 mm	0.61	9 x 7 mm	2	13 x 11 mm	6.05	18 x 13 mm	12.86
7 x 5 mm	0.75	10 x 8 mm	2.5	14 x 12 mm	8.21	20 x 15 mm	14.96

 

Pear (teardrop) diamond

This vintage cut has a large bottom and a pointed top. Since it reminds the teardrop, it is a rare choice for an engagement ring, which is a pity. The biggest option available is 19 x 14 mm with 11.7 carats.

Pear diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
6 x 4 mm	0.5	8 x 6 mm	1.25	10 x 8 mm	2.5	14 x 9 mm	4.25
7 x 5 mm	0.75	8.5 x 6.5 mm	1.5	12 x 8 mm	3	15 x 9 mm	5.06
7.7 x 5.7 mm	1	9 x 7 mm	2	12 x 9 mm	3.44	15 x 10 mm	5.75

 

Heart diamond

This stone is a visible declaration of love. It is a contemporary option that makes a traditional engagement ring less formal. The vital thing is to measure its length from the highest heart rise to its bottom point.

Heart diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
4 mm	0.25	8  mm	1.71	12 mm	5.66	15 mm	10.79
5 mm	0.44	9 mm	2.41	13 mm	7.88	16 mm	13.27
6 mm	0.74	10 mm	3.16	14 mm	9.38	18 mm	15.33
7 mm	1.13	11 mm	4.4

 

Marquise diamond

Oval marquise (football) diamonds are vintage gems of unique elliptical shape with 58 facets and pointed ends. As you can see, you need to check both the length and width of this particular diamond type.

Marquise diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
4 x 2 mm	0.1	7 x 3 mm	0.3	10 x 5 mm	1	13 x 6.5 mm	2
5 x 3  mm	0.2	8 x 4 mm	0.5	11 x 5.5 mm	1.25	14 x 7 mm	2.5
6 x 3 mm	0.25	9 x 4.5 mm	0.75	12 x 6 mm	1.5	15 x 7 mm	3

 

Asscher diamond

The Asscher cut is a trimmed square stone with large step-like facets and a high crown that provide more depth. It was fashionable in the 20s as an unavoidable art deco style piece.

Asscher diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
4.5 mm	0.5	6 mm	1.25	7.5 mm	2.5	9.5 mm	5.09
5 mm	0.75	6.5 mm	1.5	8  mm	3	11 mm	7.44
5.5 mm	1	7 mm	2	8.5 mm	3.5	12 mm	9.52

Radiant diamond

This diamond is of a square or rectangular shape and faceted to provide a glittering effect from each angle. It is a budget-friendly option for those who prefer a ring with a larger stone. You can find these gems in various sizes, up to 17 x 13 mm and 16.22 carats.

Radiant diamond Size Chart
Size	Carat	Size	Carat	Size	Carat	Size	Carat
6 x 4 mm	0.5	7.3 x 5.5 mm	1.25	9 x 7 mm	2.5	11 x 9 mm	5.05
6.5 x 4.5 mm	0.75	7.5 x 5.8 mm	1.5	9.5 x 7.5 mm	3	12 x 9 mm	6.06
7 x 5 mm	1	8 x 6  mm	2	10 x 8 mm	3.5

Summary

Many features affect the diamond’s appearance, including its shape, cut, setting, and ring style. Each gem has a precisely defined size and carat, and the ring price will directly depend on these features. Therefore, you should always use a diamond size chart for any calculations.

Sharing is caring!