Use these charts to look up the approximate carat weight
of your favorite gemstone by measuring the MM size

 

Round
Size (mm) Weight (carats)
1.6 .02
2 .03
2.5 .06
3 .10
3.5 .16
4 .25
4.5 .33
5 .50
5.5 .65
6 .75
6.5 1.0
7 1.25
8 2.0
9 2.75
10 3.5
11 4.6
12 6.0
13 7.75
14 9.65
15 11.85
16 14.35
17 17.25
18 20.5
19 24.0
20 28.0
21 34.8
22 41.8
23 49.8
24 57.9
25 68.7
 

 

Square
Size (mm) Weight (carats)
5 .75
6 1.3
7 2.05
8 2.9
9 4.4
10 6.0
11 8.0
12 10.35
13 13.2
14 16.5
15 20.25
16 24.6
 

 

Oval    
Size (mm) Weight (carats)
5 x 3 .25
6 x 4 .50
7 x 5 1.0
8 x 6 1.5
9 x 7 2.5
10 x 8 3.0
11 x 9 4.0
12 x 10 5.0
14 x 10 6.0
14 x 12 8.0
16 x 12 10.5
18 x 13 14.2
20 x 15 20.3
22 x 15 23.5
23 x 17 32.2
25 x 18 43.0
27 x 20 58.5
30 x 22 79.6
 

 

 

Emerald  
Size (mm) Weight (carats)
6 x 4 .50
7 x 5 1.0
8 x 6 1.5
9 x 7 2.5
10 x 8 3.0
11 x 9 4.0
12 x 10 5.0
14 x 10 6.0
14 x 12 8.0
16 x 12 10.5
18 x 13 14.2
20 x 15 20.3
25 x 18 52.2
 

 

    Pear     
Size (mm) Weight (carats)
6 x 5 .70
7 x 5 .75
8 x 5 1.0
9 x 6 1.5
10 x 7 2.0
11 x 7 2.25
12 x 8 3.0
13 x 9 3.5
15 x 10 5.5
16 x 12 8.6
18 x 13 12.0
20 x 15 17.3
22 x 15 18.7
25 x 18 30.6
30 x 22 54.5
 

 


Marquise
Size (mm) Weight (carats)
4 x 2 .10
5 x 2.5 .25
6 x 3 .30
8 x 4 .75
10 x 5 1.0
12 x 6 2.0
14 x 7 3.0
16 x 8 4.0
18 x 9 6.0
20 x 10 8.5
 

 

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