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Diamonds Factory
2nd Floor,
54 Hatton Garden
London
EC1N 8HN Monday - Friday : 09:30am - 05:30pm
Saturday : 09:30am - 5:30pm
Sunday : 10:00am - 4:00pm
Diamonds Factory
Shop 12
The Big Peg
Access via Warstone Lane
Birmingham
B18 6NF
Monday - Saturday : 09:00am - 05:00pm
Sunday : 10:00am - 04:00pm
Diamonds Factory
Unit 301, Third Floor
Merchants Court, 2-12 Lord Street,
Liverpool
L2 1TS Monday - Friday : 09:30am - 05:30pm
Saturday : 10:00am - 05:30pm
Sunday : Closed
Please visit our partners 'Austen & Blake' Jewellers at
17 King Street,
Manchester,
M2 6AW
Monday - Friday : 09:30am - 05:30pm
Saturday : 10:00am - 05:30pm
Sunday : 10:30am - 04:30pm

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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

CT MM
0.25 4
0.50 5.2
0.75 5.8
1.00 6.5
1.25 7.0
1.50 7.2
2.00 8.0
3.00 9.20

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.
CT MM
0.25 3.5x3.5
0.50 4.25x4.25
0.75 4.75x4.75
1.00 5.5x5.5
1.25 5.80x5.80
1.50 6.25x6.25
2.00 7x7
3.00 7.80x7.80

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.
CT MM
0.25 6.2x3.3
0.50 7.5x4.2
0.75 8.3x4.7
1.00 9.2x5.2
1.25 10.00x5.60
1.50 10.7x 5.9
2.00 12x6.5
3.00 14.50x7.00

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.
CT MM
0.25 4.2x3.2
0.50 5.3x3.8
0.75 6.3x4.4
1.00 6.6x4.8
1.25 6.80x5.10
1.50 7.5x5.5
2.00 8.5x6.3
3.00 9.60x6.80

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.
CT MM
0.25 5.5x3.6
0.50 6.5x4.6
0.75 7.6x5
1.00 8.3x5.2
1.25 9.50x6.10
1.50 9.5x6.2
2.00 10.5x7
3.00 12.00x8.60

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.
CT MM
0.25 3.8x4.2
0.50 4.7x5.3
0.75 5.9x6.5
1.00 6.3x7
1.25 6.70x7.60
1.50 7.6x8.5
2.00 8x8.8
3.00 8.20x9.85

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.
CT MM
0.25 5x3.7
0.50 6.1x4.5
0.75 7.1x5.2
1.00 7.7x5.8
1.25 8.30x5.80
1.50 8.6x 6.6
2.00 9.6x6.6
3.00 11.20x8.00

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.
CT MM
0.25 4.2x3.2
0.50 5.3x3.8
0.75 6.3x4.4
1.00 6.6x4.8
1.25 6.80x5.10
1.50 7.5x5.5
2.00 8.5x6.3
3.00 9.60x6.80

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.
CT MM
0.25 3.5x3.5
0.50 5.3x3.8
0.75 4.75x4.75
1.00 5.5x5.5
1.25 5.80x5.80
1.50 6.25x 6.25
2.00 7x7
3.00 7.80x7.80

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.
CT MM
0.25 3.5x3.5
0.50 4.25x 4.25
0.75 4.75x4.75
1.00 5.5x5.5
1.25 5.80x5.80
1.50 6.25x 6.25
2.00 7x7
3.00 7.80x7.80

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.

Get In Touch

If you'd like to talk to an expert gemologist or a member of our friendly Customer Care Team about diamond carats, please get in touch on 0800 072 1170 0800 072 1170 or enter into a Live Chat as you prefer.