Diamond Carat

A diamond's weight is measured in carats. One carat is equal to 0.2 grams. The larger the carat the heavier the diamond.

One Diamond carat is divided into 100 point. A 0.25 carat diamond is the same as a 25 points or 1/4 carat diamond. Carat is often confused with size even though it is actually a measure of weight.

Top Tips

To help you choose the perfect diamond carat, we have collated a few top tips


When choosing a diamond for a ring, it is also important to consider the length and width of the ring finger. A diamond will appear larger on longer and slimmer fingers and by comparison, shorter and wider fingers tend to make diamonds appear smaller.
When deciding on a diamond for a particular jewellery setting, the appearance in size and weight can be altered depending on the type and proportions of the setting. Delicate and slender settings tend to enhance the size and prominence of a diamond centrepiece, while larger and more solid settings can make the diamond appear smaller.
If you are on a tight budget, don't worry. Look for diamonds that fall just under popular carat weights such as 0.40, 0.90 or 1.75. These diamonds fall just shy of the most popular diamond carats, and they are often sold at a more preferable rate than full-carat diamonds. For example, a 0.90 carat diamond will typically cost less on a price-per-carat basis than a 1.00 carat diamond. Visually it's difficult to distinguish the difference between a 0.90 carat diamond and a 1.00 carat diamond.
Some shapes can make a smaller carat diamond look larger. For example, if a diamond of 0.30 carat is required to fit your budget, consider a marquise diamond cut as this appears larger than other shapes of equal carat, due to its elongated cut.
 

Diamond Carat Size Chart

MM SIZE CT WEIGHT
0.8 mm. 0.0025 ct.
1 mm. 0.005 ct.
1.12 mm. 0.0067 ct.
1.15 mm. 0.0075 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.
2.25 mm. 0.04 ct.
2.5 mm. 0.06 ct.
2.75 mm. 0.08 ct.
3 mm. 0.11 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.
MM SIZE CT WEIGHT
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.
6.25 mm. 0.93 ct.
6.5 mm. 1.00 ct.
6.8 mm. 1.25 ct.
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.
MM SIZE CT WEIGHT
9.5 mm. 3.35 ct.
9.75 mm. 3.61 ct.
10 mm. 3.87 ct.
10.25 mm. 4.16 ct.
10.5 mm. 4.41 ct.
10.75 mm. 4.57 ct.
11 mm. 4.91 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.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
1.5 mm. 0.015 ct.
1.75 mm. 0.03 ct.
2 mm. 0.06 ct.
2.25 mm. 0.08 ct.
2.5 mm. 0.10 ct.
2.75 mm. 0.13 ct.
3 mm. 0.18 ct.
3.25 mm. 0.26 ct.
3.5 mm. 0.29 ct.
3.75 mm. 0.31 ct.
4 mm. 0.39 ct.
4.25 mm. 0.44 ct.
4.5 mm. 0.50 ct.
MM SIZE CT WEIGHT
4.75 mm. 0.64 ct.
5 mm. 0.75 ct.
5.25 mm. 0.90 ct.
5.5 mm. 1.00 ct.
5.75 mm. 1.11 ct.
6 mm. 1.25 ct.
6.25 mm. 1.39 ct.
6.5 mm. 1.50 ct.
6.75 mm. 1.75 ct.
7 mm. 2.00 ct.
7.25 mm. 2.01 ct.
7.5 mm. 2.50 ct.
7.75 mm. 2.74 ct.
MM SIZE CT WEIGHT
8 mm. 3.00 ct.
8.25 mm. 3.24 ct.
8.5 mm. 3.67 ct.
8.75 mm. 4.10 ct.
9 mm. 4.12 ct.
9.5 mm. 5.09 ct.
9.75 mm. 5.36 ct.
10 mm. 5.62 ct.
10.25 mm. 5.76 ct.
10.5 mm. 5.99 ct.
11 mm. 7.44 ct.
11.5 mm. 9.44 ct.
12 mm. 9.52 ct.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
3x1.5 mm. 0.025 ct.
3.5x1.75 mm. 0.065 ct.
3.5x2 mm. 0.07 ct.
4x2 mm. 0.10 ct.
3.75x1.75 mm. 0.11 ct.
4.25x2.25 mm. 0.12 ct.
5x2.5 mm. 0.14 ct.
5.5x2.75 mm. 0.16 ct.
5.5x3 mm. 0.18 ct.
5x3 mm. 0.20 ct.
6.5x3 mm. 0.23 ct.
6x3 mm. 0.25 ct.
MM SIZE CT WEIGHT
7x3 mm. 0.30 ct.
7.5x3.5 mm. 0.33 ct.
7x4 mm. 0.34 ct.
8x4 mm. 0.50 ct.
8.75x4.25 mm. 0.70 ct.
9x4.5 mm. 0.75 ct.
9.5x4.7 mm. 0.85 ct.
10x5 mm. 1.00 ct.
11x5.5 mm. 1.25 ct.
11.5x6 mm. 1.33 ct.
12x6 mm. 1.50 ct.
13x6.5 mm. 2.00 ct.
MM SIZE CT WEIGHT
14x7 mm. 2.50 ct.
15x7 mm. 3.00 ct.
14x8 mm. 3.00 ct.
15x7.5 mm. 3.25 ct.
15x8 mm. 3.44 ct.
16x8 mm. 3.86 ct.
16.5x8.25 mm. 4.00 ct.
17x8.5 mm. 4.88 ct.
17.5x10 mm. 5.50 ct.
20x8 mm. 7.08 ct.
20x10 mm. 7.94 ct.
20x11 mm. 9.50 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.



Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
3x2 mm. 0.10 ct.
3.5x2 mm. 0.12 ct.
4x2 mm. 0.15 ct.
4x3 mm. 0.20 ct.
5x3 mm. 0.29 ct.
5.5x3.5 mm. 0.46 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.75 ct.
6.7x4.5 mm. 0.88 ct.
MM SIZE CT WEIGHT
7x5 mm. 1.00 ct.
7.3x5.3 mm. 1.25 ct.
7.5x5.5 mm. 1.50 ct.
8x6 mm. 1.75 ct.
8.5x6.5 mm. 2.00 ct.
9x7 mm. 2.50 ct.
10x7.5 mm. 3.00 ct.
9.5x7.5 mm. 3.21 ct.
10x8 mm. 3.79 ct.
MM SIZE CT WEIGHT
11x9 mm. 5.21 ct.
12x8 mm. 5.34 ct.
12x10 mm. 6.00 ct.
14x8 mm. 6.25 ct.
13x9 mm. 6.38 ct.
14x10 mm. 8.48 ct.
13x11 mm. 9.13 ct.
14x12 mm. 11.26 ct.
16x12 mm. 14.22 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
3x2 mm. 0.13 ct.
4x2.5 mm. 0.18 ct.
4x3 mm. 0.21 ct.
5x3 mm. 0.25 ct.
5x4 mm. 0.35 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.60 ct.
7x5 mm. 0.75 ct.
7.5x5.5 mm. 0.85 ct.
7.7x5.7 mm. 1.00 ct.
8x6 mm. 1.25 ct.
8.5x6.5 mm. 1.50 ct.
10x6 mm. 1.71 ct.
MM SIZE CT WEIGHT
8.7x6.7 mm. 1.80 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
11x7.50 mm. 2.61 ct.
13x8 mm. 2.98 ct.
11x8 mm. 3.00 ct.
12x8 mm. 3.00 ct.
12x7 mm. 3.12 ct.
12x9 mm. 3.44 ct.
14x8 mm. 3.47 ct.
13x9 mm. 4.11 ct.
14x9 mm. 4.25 ct.
MM SIZE CT WEIGHT
15x9 mm. 5.06 ct.
14x10 mm. 5.41 ct.
13x11 mm. 5.65 ct.
15x10 mm. 5.75 ct.
16x9 mm. 5.86 ct.
16x10 mm. 6.27 ct.
17x10 mm. 6.46 ct.
15x11 mm. 7.36 ct.
18x11 mm. 8.14 ct.
16x12 mm. 8.99 ct.
18x12 mm. 9.35 ct.
18x13 mm. 10.21 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
3.5 mm. 0.18 ct.
4 mm. 0.25 ct.
4.25 mm. 0.28 ct.
4.5 mm. 0.34 ct.
4.75 mm. 0.38 ct.
5 mm. 0.50 ct.
5.5 mm. 0.61 ct.
6 mm. 0.75 ct.
MM SIZE CT WEIGHT
6.25 mm. 0.83 ct.
6.5 mm. 1.00 ct.
7 mm. 1.25 ct.
7.5 mm. 1.50 ct.
8 mm. 2.00 ct.
8.5 mm. 2.50 ct.
9 mm. 3.00 ct.
10 mm. 3.50 ct.
MM SIZE CT WEIGHT
11 mm. 4.41 ct.
12 mm. 5.66 ct.
13 mm. 7.88 ct.
14 mm. 9.38 ct.
15 mm. 10.79 ct.
16 mm. 13.27 ct.
18 mm. 15.33 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
4.5x3.5 mm. 0.21 ct.
5x3 mm. 0.21 ct.
5.5x3.5 mm. 0.33 ct.
5x4 mm. 0.35 ct.
6x4 mm. 0.50 ct.
6x5 mm. 0.61 ct.
6.5x4.5 mm. 0.65 ct.
7x5 mm. 0.75 ct.
7.7x5.7 mm. 1.00 ct.
MM SIZE CT WEIGHT
8x6 mm. 1.25 ct.
9x6 mm. 1.41 ct.
8.5x6.5 mm. 1.50 ct.
9x7 mm. 2.00 ct.
10x8 mm. 2.50 ct.
10.5x8.5 mm. 2.88 ct.
12x8 mm. 3.00 ct.
11x9 mm. 3.85 ct.
12x10 mm. 5.05 ct.
MM SIZE CT WEIGHT
14x10 mm. 5.81 ct.
13x11 mm. 6.05 ct.
14x12 mm. 8.21 ct.
15x12 mm. 8.76 ct.
16x12 mm. 9.32 ct.
16x14 mm. 11.88 ct.
18x13 mm. 12.86 ct.
20x15 mm. 14.96 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
5x3 mm. 0.31 ct.
4.5x3.5 mm. 0.34 ct.
6x3 mm. 0.41 ct.
6x4 mm. 0.50 ct.
6.5x4.5 mm. 0.75 ct.
7x5 mm. 1.00 ct.
7.3x5.5 mm. 1.25 ct.
7.5x5.8 mm. 1.50 ct.
8x6 mm. 2.00 ct.
MM SIZE CT WEIGHT
8.5x6.5 mm. 2.25 ct.
9x7 mm. 2.50 ct.
9.5x7.5 mm. 3.00 ct.
10x7 mm. 3.31 ct.
10x8 mm. 3.50 ct.
11x9 mm. 5.05 ct.
12x9 mm. 6.06 ct.
11.5x10 mm. 6.45 ct.
13x9 mm. 6.54 ct.
MM SIZE CT WEIGHT
12x10 mm. 6.79 ct.
14x10 mm. 8.47 ct.
13x11 mm. 9.33 ct.
13.5x11.5 mm. 10.19 ct.
15x11 mm. 11.48 ct.
14x12 mm. 12.14 ct.
16x12 mm. 14.22 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
4 mm. 0.39 ct.
4.5 mm. 0.50 ct.
5 mm. 0.75 ct.
5.5 mm. 1.00 ct.
6 mm. 1.25 ct.
6.5 mm. 1.50 ct.
MM SIZE CT WEIGHT
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.12 ct.
9.5 mm. 5.09 ct.
MM SIZE CT WEIGHT
10 mm. 5.62 ct.
11 mm. 7.44 ct.
12 mm. 9.52 ct.
13 mm. 12.66 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
MM SIZE CT WEIGHT
4.2 mm. 0.40 ct.
4.9 mm. 0.50 ct.
5.25 mm. 0.75 ct.
5.5 mm. 1.00 ct.
6 mm. 1.25 ct.
6.5 mm. 1.50 ct.
MM SIZE CT WEIGHT
7 mm. 2.00 ct.
7.5 mm. 2.50 ct.
8 mm. 3.00 ct.
8.5 mm. 3.50 ct.
9 mm. 4.12 ct.
MM SIZE CT WEIGHT
9.5 mm. 5.09 ct.
10 mm. 5.62 ct.
11 mm. 7.44 ct.
12 mm. 9.52 ct.
13 mm. 12.66 ct.

All diamonds are all divisible by the method outlined above. Some very rare diamonds can weigh 100 carats or more and be worth many millions of pounds.

Notes

  • Carat is measurement of WEIGHT, not SIZE and the overall diameter (mm) could differe slighter larger or smaller even through carat weight is correct.
  • Image not to scale. Diamond pictures are shown for comparison purpose only. Actual size can very depending your screen resolutions, monitor size etc.
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