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The Carat Weight of Your Diamond

Diamond carat weight explained.  Diamond sizes compared.

Diamond Sizes on a Hand

Diamonds and other gem stones are measured in carats, a word derived from 'carob' meaning seed, the first measuring unit for diamond traders. One carat equals 200 milligrams of weight. Carat weight is the fourth of the 4Cs in the Monroe Yorke Diamonds Diamond Education. The term 'carat' is often abbreviated to 'ct' and will refer to the weight of a single diamond. Carat TW or ct TW refers to total carat weight and is used to represent the weight of a number of diamonds that are presented together in one piece of jewellery. The word 'caratage' is an expression of purity for gold. Below is a diagram of how carat weight is expressed:

The term 'carat weight' is also used for other gemstones, such as pearls and fancy coloured diamonds. Gems of similar weight are not always the same size, because by virtue of their unique qualities, gemstones have different densities. Therefore, to clarify :~

  • Carat weight does not in itself determine the size of a diamond.
  • The carat weight of a diamond should be taken into account along with cut, colour and clarity when determining the value of a diamond.

To clarify size and weight, refer to the:~

Monroe Yorke Diamonds Diamond Size Comparison Chart

As one would expect, the larger a diamond's carat weight, the higher the price. But the price you pay is also determined by those other important factors, the 4Cs that are displayed on the GIA or HRD Diamond Grading Report.

If, when purchasing your diamond, size is important, then the 'carat weight' will be the grading that you will be most interested in. As the carat size increases, then so does it's price, but even in larger more expensive diamonds, there is a differential in quality. Less than one in one million rough diamonds will be large enough to produce a finished diamond that weighs one carat.

A diamonds carat weight is not only priced per total of weight, but the unit price of the carat will also increase. 

Diamonds should always be viewed from above and it's measurements should also be taken into consideration as it's cut proportions will vary. The length and width of a diamond is an important indication of the how the diamond will look when viewed from above. The diagram below explains this in more detail:~

A diamond that has been cut with a greater depth, has a larger distribution of weight contained in the depth which will result in a diameter that is smaller. Although the differences between a number of diamonds will be small in comparison to the overall scale, they will be noticeable, even to the naked eye.

The chosen cut of the diamond such as round, cushion, emerald or heart is also paramount to the appearance of size and it's overall carat weight.

Different shapes of diamond should not be compared when assessing the size of a diamond. A 1.00 carat round diamond may appear smaller than a 1.00 carat marquise, for example.

All diamonds should be assessed by and for their unique qualities. For more information and advice regarding 'carat weight,' contact Monroe Yorke Diamonds on 1800 766 567 and speak with one of our professional diamond specialists.

Compare diamond sizes here: 


Diamond size chart showing diamond millimetre (mm) sizes