While carat weight of a diamond is stated in standard values like 0.50 ct, 0.75 ct, 1.0 ct, etc., in actuality, there is rarely a diamond whose weight corresponds to any of these numbers. A one carat diamond is likely to be either 0.95 or 1.05 carats in weight. That is why you should not expect two diamonds, having the same carat weight in the advertisement, to be perfectly similar in terms of their weight.
It is actually normal for it not to be a precise or standard number. Typically, when the carat weight of a diamond is advertised, either the stone’s certificate or jeweler will reveal that the carat weight is approximate. This is common practice in the jewelry industry, and the value is typically made known to customers of diamonds. Buyers can find the precise carat weight in a GIA diamond grading report or certificate as well.
So, you might now be wondering how visible the difference in the carat weight is. Of course, compare a one ct diamond with another one that weighs 0.75 carat and you will be able to tell apart the difference going by their respective size. However, when the weight difference is 0.05 carat, it is barely detectable with the naked eye.
If a diamond weighing 0.95 carat is put next to another one weighing 1.02 carat, for instance, it is very likely that you will need to look hard to identify the difference. Besides, when a diamond weighing 0.95 carat is worn, not all will be able to notice that the stone is not precisely one carat.
Typically, the real weight of a diamond will be inside 0.06 to 0.08 carats of the stone’s advertised weight. For example, a diamond weighing 0.94 carat will be advertised as a one carat diamond. Moreover, a diamond advertised to be 0.75 carats in weight may actually be closer to 0.80 carats.
It is always recommended to buy a diamond or diamond engagement ring with a diamond certificate, issued by a reliable institute such as the GIA to name one. However, if your jeweler is in a different geographical area to the US or simply does not offer you the grading report option, then you can always ask them about the precise weight of the stone you are looking for. Even when you are making the purchase of a diamond jewelry piece, you have to do the same.