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Diamond Size & Weight Chart

One of the most frequent questions we get when discussing the purchase of loose diamonds is "How big is a 1ct diamond?" From the Four C's of Diamonds, two of the C's play an important role here when talking "size" - carat weight and cut.

"Carat weight" is the physical weight of a diamond therefore a 1ct diamond weighs 1ct (100 points). Depending on the shape and cut of the diamond, the diamond can appear to be larger or smaller. This is where the cut comes into play along with the depth of the stone. A stone with a deep cut, displays smaller because the stone is "taller" and more narrow. A shallow cut diamond will measure larger, however the light and sparkle with be less than an "ideal cut" diamond.

To best estimate carat size and mm size, it's easiest to use ideal cut diamonds. Ideal cut diamonds are cut to maximize the brilliance of a diamond by allowing the light to reflect perfectly.

This table below shows some approximations of carat weight and physical measurements. And remember, as cut can vary tremendously, these are only general approximations based on ideal cut diamonds.

 

Diamond Carat Weight to Size Chart

 

Round Brilliant Sizing

MM Size Carat Weight MM Size Carat Weight
0.8 0.0025 7 1.28
1 0.005 7.25 1.49
1.12 0.0075 7.5 1.67
1.15 0.0067 7.75 1.75
1.25 0.01 8 2.04
1.3 0.01 8.25 2.11
1.5 0.015 8.5 2.43
1.75 0.02 8.75 2.55
1.8 0.025 9 2.75
2 0.03 9.25 3.05
2.25 0.04 9.5 3.35
2.5 0.06 9.75 3.61
2.75 0.08 10 3.87
3 0.11 10.25 4.16
3.25 0.14 10.5 4.41
3.5 0.17 10.75 4.57
3.75 0.21 11 4.91
4 0.25 11.25 5.49
4.25 0.28 11.5 5.85
4.5 0.36 12 6.84
4.75 0.44 12.25 7.26
5 0.46 12.5 7.36
5.25 0.56 12.75 7.52
5.5 0.66 13 8.51
5.75 0.76 13.5 9.53
6 0.84 14 10.49
6.25 0.93 15 12.89
6.5 1.03 16 16.06
6.75 1.24

 

Princess Cut Sizing

MM Size Carat Weight MM Size Carat Weight
1.5 0.015 6.5 1.59
1.75 0.03 6.75 1.75
2 0.06 7 1.96
2.25 0.08 7.25 2.01
2.5 0.1 7.5 2.4
2.75 0.13 7.75 2.74
3 0.18 8 3.01
3.25 0.26 8.25 3.24
3.5 0.29 8.5 3.67
3.75 0.31 8.75 4.1
4 0.39 9 4.12
4.25 0.44 9.5 5.09
4.5 0.56 9.75 5.36
4.75 0.64 10 5.62
5 0.71 10.25 5.76
5.25 0.75 10.5 5.99
5.5 0.99 11 7.44
5.75 1.11 11.5 9.44
6 1.24 12 9.52
6.25 1.39

 

Asscher Cut Sizing

MM Size Carat Weight MM Size Carat Weight
4 0.39 8 3.01
4.5 0.56 8.5 3.67
5 0.71 9 4.12
5.5 0.99 9.5 5.09
6 1.24 10 5.62
6.5 1.59 11 7.44
7 1.96 12 9.52
7.5 2.4 13 12.66

 

Marquise Sizing

MM Size Carat Weight MM Size Carat Weight
3 x 1.5 0.025 9.5 x 2 0.85
3.5 x 1.75 0.065 10 x 5 0.95
3.5 x 2 0.07 11 x 5.5 1.25
3.75 x 1.75 0.11 11.5 x 6 1.33
4 x 2 0.1 12 x 6 1.62
4.25 x 2.25 0.12 12 x 6.5 1.71
5 x 2.5 0.14 13 x 6.5 2.11
5 x 3 0.2 14 x 7 2.48
5.5 x 2.75 0.16 15 x 7.5 3.09
5.5 x 3 0.18 14 x 8 3
6 x 3 0.25 15 x 7 3.12
6.5 x 3 0.23 15 x 8 3.44
7 x 3 0.3 16 x 8 3.86
7 x 3.5 0.35 17 x 8.5 4.88
7 x 4 3.4 17.5 x 10 5.5
7.5 x 3.5 0.33 20 x 8 7.08
8 x 4 0.47 20 x 10 7.94
9 x 4.5 0.71 20 x 11 9.5
9 x 5 0.76

 

Radiant Cut Sizing

MM Size Carat Weight MM Size Carat Weight
4.5 x 3.5 0.34 10 x 8 3.49
5 x 3 0.31 11 x 9 5.05
6 x 3 0.41 11.5 x 10 6.45
6 x 4 0.6 12 x 9 6.06
6.5 x 4.5 0.83 12 x 10 6.79
7 x 5 1.14 13 x 9 6.54
7.25 x 5.25 1.24 13 x 11 9.33
7.5 x 5.5 1.47 13.5 x 11.5 10.19
8 x 6 1.74 14 x 10 8.47
8.5 x 6.5 2.25 14 x 12 12.14
9 x 7 2.62 15 x 11 11.48
9.5 x 7.5 3.18 16 x 12 14.22
10 x 7 3.31

 

Cushion Cut Sizing

MM Size Carat Weight MM Size Carat Weight
4 0.25 8 2.04
4.5 0.36 8.5 2.43
5 0.46 9 2.75
5.25 0.56 9.5 3.35
5.5 0.66 10 3.87
5.75 0.76 10.5 4.41
6 0.84 11 4.91
6.25 0.93 11.5 5.85
6.5 1.03 12 6.84
6.75 1.24 13 8.51
7 1.28 14 10.49
7.5 1.67 15 12.89

 

Pear Shape Sizing

MM Size Carat Weight MM Size Carat Weight
3 x 2 0.13 12 x 8 3
4 x 2.5 0.18 12 x 9 3.44
4 x 3 0.21 13 x 8 2.98
5 x 3 0.25 14 x 8 3.47
5 x 4 0.35 13 x 9 4.11
6 x 4 0.39 14 x 9 4.25
6.5 x 4.5 0.57 15 x 9 5.06
7 x 5 0.71 14 x 10 5.41
8 x 5 0.81 13 x 11 5.65
8.5 x 5.5 1.08 15 x 10 5.75
8 x 6 1.25 15 x 11 7.36
9 x 6 1.33 16 x 9 5.86
9 x 7 1.75 16 x 10 6.27
10 x 6 1.71 16 x 12 8.99
10 x 7 1.8 17 x 10 6.46
10 x 8 2.46 18 x 11 8.14
11 x 7.50 2.61 18 x 12 9.35
11 x 8 3 18 x 13 10.21
12 x 7 3.12

 

Oval Shape Sizing

MM Size Carat Weight MM Size Carat Weight
4.5 x 3.5 0.21 10 x 8 2.54
5 x 3 0.21 10.5 x 8.5 2.88
5 x 4 0.35 11 x 9 3.85
5.5 x 3.5 0.33 12 x 8 2.99
6 x 4 0.43 12 x 10 5.05
6.5 x 4.5 0.65 14 x 10 5.81
6 x 5 0.61 13 x 11 6.05
7 x 5 0.76 14 x 12 8.21
7.5 x 5.5 0.98 15 x 12 8.76
8 x 6 1.21 16 x 12 9.32
8.5 x 6.5 1.46 16 x 14 11.88
9 x 6 1.41 18 x 13 12.86
9 x 7 1.86 20 x 15 14.96

 

Heart Shape Sizing

MM Size Carat Weight MM Size Carat Weight
3.5 0.18 8 1.71
4 0.25 9 2.41
4.25 0.28 9.5 2.9
4.5 0.34 10 3.16
4.75 0.38 11 4.41
5 0.44 12 5.66
5.5 0.61 13 7.88
6 0.74 14 9.38
6.25 0.83 15 10.79
6.5 0.93 16 13.27
7 1.13 18 15.33
7.5 1.59

 

Trillion Sizing

MM Size Carat Weight MM Size Carat Weight
3 0.12 6.25 0.75
3.5 0.16 6.5 0.91
3.75 0.19 6.75 0.98
4 0.23 7 1.1
4.25 0.27 7.5 1.21
4.5 0.31 8 1.75
4.75 0.37 9 2.35
5 0.42 11 3.66
5.25 0.49 12 4.9
5.5 0.55 13 6.42
5.75 0.64 15 9
6 0.7

 

Emerald Cut Sizing

MM Size Carat Weight MM Size Carat Weight
3 x 2 0.1 9 x 7 2.62
3.5 x 2 0.12 9.5 x 7.5 3.21
4 x 2 0.15 10 x 7 3.01
4 x 3 0.2 10 x 8 3.79
5 x 3 0.29 11 x 9 5.21
5.5 x 3.5 0.46 12 x 8 5.34
5.5 x 4 0.48 12 x 10 6
6 x 4 0.66 13 x 9 6.38
6.5 x 4.5 0.88 14 x 8 6.25
7 x 5 1.06 14 x 10 8.48
7.25 x 5.25 1.24 13 x 11 9.13
7.5 x 5.5 1.45 14 x 12 11.26
8 x 6 1.74 16 x 12 14.22
8.5 x 6.5 2.17

 

Triangle Cut Sizing

MM Size Carat Weight MM Size Carat Weight
2.5 0.08 7 1.11
3 0.12 7.25 1.32
3.5 0.18 7.5 1.45
4 0.25 7.75 1.69
4.25 0.32 8 1.79
4.5 0.37 8.25 1.86
4.75 0.42 9 2.15
5 0.45 9.25 2.54
5.25 0.53 9.75 3.25
5.5 0.66 10 3.52
5.75 0.71 11 4.74
6 0.76 12 6.03
6.25 0.86 13 8.12
6.5 0.94 14 9.83
6.75 1.02

 

Tapered Baguette Sizing

MM Size Carat Weight MM Size Carat Weight
2 x 1.5 x 1 0.025 4.25 x 2 x 1.5 0.13
2.5 x 1.5 x 1 0.035 4.25 x 2.5 x 1.25 0.13
2.5 x 1.75 x 1 0.04 4.25 x 2.5 x 1.5 0.135
3 x 1.5 x 1 0.05 4.5 x 1.75 x 1.25 0.15
3 x 1.75 x 1.25 0.055 4.5 x 2 x 1.5 0.12
3 x 1.75 x 1.3 0.055 4.5 x 2.3 x 1.8 0.16
3 x 1.75 x 1.5 0.055 4.5 x 2.5 x 2 0.15
3 x 2 x 1 0.06 4.5 x 2.75 x 1.75 0.15
3 x 2 x 1.25 0.065 4.5 x 3 x 2 0.16
3 x 2 x 1.5 0.07 4.5 x 3 x 2.5 0.16
3 x 2 x 1.75 0.075 4.75 x 2.5 x 1.5 0.15
3 x 2.5 x 2 0.08 4.75 x 3 x 2 0.18
3.25 x 1.75 x 1 0.07 5 x 2 x 1 0.14
3.25 x 1.75 x 1.25 0.05 5 x 2 x 1.25 0.15
3.5 x 1.25 x 1 0.04 5 x 2 x 1.5 0.15
3.5 x 1.5 x 1 0.05 5 x 2.3 x 1.8 0.16
3.5 x 1.5 x 1.25 0.055 5 x 2.5 x 1.5 0.2
3.5 x 1.7 x 1.3 0.055 5 x 2.5 x 2 0.21
3.5 x 1.75 x 1 0.06 5 x 2.75 x 2 0.21
3.5 x 1.75 x 1.25 0.07 5 x 3 x 2 0.25
3.5 x 1.75 x 1.3 0.065 5 x 3.5 x 2 0.26
3.5 x 2 x 1.25 0.08 5 x 4 x 3.5 0.28
3.5 x 2 x 1.5 0.09 5.5 x 2 x 1.5 0.18
3.5 x 2.5 x 2 0.09 5.5 x 2.5 x 1.75 0.23
3.75 x 2 x 1.25 0.08 5.5 x 2.5 x 2 0.23
4 x 1.5 x 1 0.07 5.5 x 3 x 2 0.26
4 x 1.5 x 1.2 0.08 5.5 x 3 x 2.25 0.26
4 x 1.75 x 1.25 0.08 5.5 x 4 x 2.5 0.28
4 x 2 x 1.5 0.1 6 x 2 x 1.5 0.3
4 x 2.5 x 1.5 0.12 6 x 2.5 x 1.5 0.3
4 x 2.5 x 2 0.21 6 x 3 x 2 0.3
4 x 3 x 2 0.21 6.5 x 2.5 x 2 0.3
4.25 x 2 x 1.25 0.11 6.5 x 3 x 2 0.32

 

Rectangular Baguette Sizing

MM Size Carat Weight MM Size Carat Weight
2 x 1 0.02 3.75 x 1.5 0.14
2 x 1.5 0.04 3.75 x 2 0.145
2 x 1.75 0.04 4 x 1.25 0.075
2.25 x 1.75 0.04 4 x 1.5 0.08
2.25 x 2 0.045 4 x 1.75 0.11
2.5 x 1 0.045 4 x 2 0.14
2.5 x 1.25 0.047 4 x 3 0.2
2.5 x 1.5 0.05 4.5 x 1.5 0.1
2.5 x 1.75 0.055 4.5 x 1.75 0.14
2.5 x 2 0.055 4.5 x 2 0.17
2.75 x 1.5 0.055 4.5 x 2.5 0.2
2.75 x 1.75 0.06 4.5 x 3 0.285
2.75 x 2 0.06 4.5 x 3.5 0.3
2.75 x 2.5 0.065 4.75 x 1.5 0.27
3 x 1 0.05 4.75 x 2 0.28
3 x 1.25 0.055 5 x 1.5 0.14
3 x 1.5 0.06 5 x 1.75 0.15
3 x 1.75 0.08 5 x 2 0.19
3 x 2 0.1 5 x 2.5 0.24
3 x 2.5 0.13 5 x 3 0.3
3.25 x 1.25 0.06 5 x 3.5 0.33
3.25 x 1.5 0.065 5 x 4 0.4
3.25 x 1.75 0.08 5.5 x 1.75 0.16
3.25 x 2.5 0.14 5.5 x 2 0.18
3.5 x 1 0.065 5.5 x 2.5 0.23
3.5 x 1.25 0.07 5.5 x 3 0.3
3.5 x 1.5 0.07 5.5 x 3.5 0.33
3.5 x 1.75 0.08 6 x 1.75 0.28
3.5 x 2 0.13 6 x 2 0.3
3.5 x 2.5 0.15 6 x 2.5 0.33
3.5 x 3 0.15 6 x 3 0.4