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   PRINCESS / SQUARE   EMERALD
Size Weight   Size Weight   Size Weight
1.6 mm 0.02 carat   5 mm 0.75 carat   6 x 4 mm 0.50 carat
2 mm 0.03 carat   6 mm 1.30 carat   7 x 5 mm 1.00 carat
2.5 mm 0.06 carat   7 mm 2.05 carat   8 x 6 mm 1.50 carat
3 mm 0.10 carat   8 mm 2.90 carat   9 x 7 mm 2.50 carat
3.5 mm 0.16 carat   9 mm 4.40 carat   10 x 8 mm 3.00 carat
4 mm 0.25 carat   10 mm 6.00 carat   11 x 9 mm 4.00 carat
4.5 mm 0.33 carat   11 mm 8.00 carat   12 x 10 mm 5.00 carat
5 mm 0.50 carat   12 mm 10.35 carat   14 x 10 mm 6.00 carat
5.5 mm 0.65 carat   13 mm 13.20 carat   14 x 12 mm 8.00 carat
6 mm 0.75 carat   14 mm 16.50 carat   16 x 12 mm 10.50 carat
6.5 mm 1.00 carat   15 mm 20.25 carat   18 x 13 mm 14.20 carat
7 mm 1.25 carat   16 mm 24.60 carat   20 x 15 mm 20.30 carat
8 mm 2.00 carat   20 x 15 mm 20.30 carat   25 x 18 mm 52.20 carat
9 mm 2.75 carat   22 x 15 mm 23.50 carat   25 x 18 mm 30.60 carat
10 mm 3.50 carat   23 x 17 mm 32.20 carat   30 x 22 mm 54.50 carat
11 mm 4.60 carat   25 x 18 mm 43.00 carat      
12 mm 6.00 carat   27 x 20 mm 58.50 carat   PEAR
13 mm 7.75 carat   30 x 22 mm 79.60 carat   Size Weight
14 mm 9.65 carat         6 x 5 mm 0.70 carat
15 mm 11.85 carat   OVAL   7 x 5 mm 0.75 carat
16 mm 14.35 carat   Size Weight   8 x 5 mm 1.00 carat
17 mm 17.25 carat   5 x 3 mm 0.25 carat   9 x 6 mm 1.50 carat
18 mm 20.50 carat   6 x 4 mm 0.50 carat   10 x 7 mm 2.00 carat
19 mm 24.00 carat   7 x 5 mm 1.00 carat   11 x 7 mm 2.25 carat
20 mm 28.00 carat   8 x 6 mm 1.50 carat   12 x 8 mm 3.00 carat
21 mm 34.80 carat   9 x 7 mm 2.50 carat   13 x 9 mm 3.50 carat
22 mm 41.80 carat   10 x 8 mm 3.00 carat   15 x 10 mm 5.50 carat
23 mm 49.80 carat   11 x 9 mm 4.00 carat   16 x 12 mm 8.60 carat
24 mm 57.90 carat   12 x 10 mm 5.00 carat   18 x 13 mm 120 carat
25 mm 68.70 carat   14 x 10 mm 6.00 carat   20 x 15 mm 17.30 carat
      14 x 12 mm 8.00 carat   22 x 15 mm 18.70 carat
EMERALD   16 x 12 mm 10.50 carat      
Size Carat Weight   18 x 13 mm 14.20 carat   TRILLION
3 x 2 mm 0.10 carat         MM Size Carat Weight
3.5 x 2 mm 0.12 carat   CUSHION   3 mm 0.12 carat
4 x 2 mm 0.15 carat   MM Size Carat Weight   3.5 mm 0.16 carat
4 x 3 mm 0.20 carat   5.25 mm 0.56 carat   3.75 mm 0.19 carat
5 x 3 mm 0.29 carat   5.5 mm 0.66 carat   4 mm 0.23 carat
5.5 x 3.5 mm 0.46 carat   5.75 mm 0.76 carat   4.25 mm 0.27 carat
5.5 x 4 mm 0.48 carat   6 mm 0.84 carat   4.5 mm 0.31 carat
6 x 4 mm 0.66 carat   6.25 mm 0.93 carat   4.75 mm 0.37 carat
6.5 x 4.5 mm 0.88 carat   6.5 mm 1.03 carat   5 mm 0.42 carat
7 x 5 mm 1.06 carat   6.75 mm 1.24 carat   5.25 mm 0.49 carat
7.25 x 5.25 mm 1.24 carat   7 mm 1.28 carat   5.5 mm 0.55 carat
7.5 x 5.5 mm 1.45 carat   7.5 mm 1.67 carat   5.75 mm 0.64 carat
8 x 6 mm 1.74 carat   8 mm 2.04 carat   6 mm 0.7 carat
8.5 x 6.5 mm 2.17 carat   8.5 mm 2.43 carat   6.25 mm 0.75 carat
9 x 7 mm 2.62 carat   9 mm 2.75 carat   6.5 mm 0.91 carat
9.5 x 7.5 mm 3.21 carat   9.5 mm 3.35 carat   6.75 mm 0.98 carat
10 x 7 mm 3.01 carat         7 mm 1.1 carat
      ASCCHER   7.5 mm 1.21 carat
MARQUISE   MM Size Carat Weight   8 mm 1.75 carat
MM Size Carat Weight   4 mm 0.40 carat   9 mm 2.35 carat
8 x 4 mm 0.47 carat   4.5 mm 0.56 carat   11 mm 3.66 carat
9 x 4.5 mm 0.71 carat   5 mm 0.70 carat      
9 x 5 mm 0.76 carat   5.5 mm 1.00 carat   RADIANT
9.5 x 2 mm 0.85 carat   6 mm 1.24 carat   MM Size Carat Weight
10 x 5 mm 0.95 carat   6.5 mm 1.59 carat   6.5 x 4.5 mm 0.83 carat
11 x 5.5 mm 1.25 carat   7 mm 1.96 carat   7 x 5 mm 1.14 carat
11.5 x 6 mm 1.33 carat   7.5 mm 2.40 carat   7.25 x 5.25 mm 1.24 carat
12 x 6 mm 1.62 carat   8 mm 3.00 carat   7.5 x 5.5 mm 1.47 carat
12 x 6.5 mm 1.71 carat   8.5 mm 3.67 carat   8 x 6 mm 1.74 carat
13 x 6.5 mm 2.11 carat   9 mm 4.12 carat   8.5 x 6.5 mm 2.25 carat
14 x 7 mm 2.48 carat   9.5 mm 5.09 carat   9 x 7 mm 2.62 carat
15 x 7.5 mm 3.09 carat   10 mm 5.62 carat   9.5 x 7.5 mm 3.18 carat
14 x 8 mm 3.00 carat          

 

If you have any additional questions or would like assistance in finding that perfect diamond, please reach out and speak with one of our GIA Graduate Gemologists for a free consultation.

 

 

 

 

 

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