The weight of a diamond is measured in carats (ct), with one carat being 200mg. The carat can also be divided up into 100 points for smaller stones. For instance, a five-point diamond will weigh 0.05 carats or 10 milligrams. If a piece of jewellery includes a number of diamonds, it is common to see carat total weight (ct TW) used as the unit of measurement. Remember that this is not the same thing that you may hear with regards to gold, where ‘carat’ is used as a measure of purity, not weight
Weight vs Size
It is worth noting that carat and size are not always proportional, that is, a diamond with a greater carat weight is not necessarily a larger size, given that diamond size is also affected by shape and cut. Only if the cut and shape of two stones are exactly the same can the carat weight be used to compare the sizes of two stones and estimate which is indeed larger.
Carat and Value
Many people will think about carats exclusively when enquiring about diamonds, but the true value of a gem depends on all of The 4 Cs:
To see how these work together, consider a 2-carat and a 1-carat diamond. If the former is poorly cut, contains imperfections and is discoloured, it may be worth far less than the second, smaller stone. Therefore, it is only worth comparing carat weights if the properties of the two diamonds are the same or at least similar. While a larger stone might seem nice, it is important to consider all of the factors of diamond quality to get a true assessment of a stone’s value.
Carats and Rarity
Despite the above interconnections, it is true to say that larger diamonds are rarer. Most stones are quite small when found in the wild and will lose 40-60% of its original rough size when cut down and polished into its final form. Because of this rarity, jewellers often sell larger stones with a higher price tag. However, as we mentioned before, it is always prudent to ask about the cut, clarity, and colour of the diamond as well as the carat to make sure the weight you choose is really worth the value which has been stated.
If you would like advice about how important the size of a diamond is relative to its other important characteristics, please get in contact with one of our master jewellers. We have a range of diamonds and diamond engagement rings in our Sydney store of varying sizes and styles that we can use to show you around the major differences.