Sizes
Although the term carat is universal in determining gemstone weight, due to different densities or specific gravity (SG) of gemstones, they don’t all visually appear the same.
A 1ct diamond will not look the same size as a 1ct sapphire, but they will weigh the same! That’s why it’s important to bear in mind the individual dimensions of stones.
There are what are called ‘magic’ carat weights for diamonds particularly. At these points, 0.5ct, 0.75ct, 1ct, 1.25, 1.5ct etc, is where there will be price increases. At the carat point particularly this is noticeable. Buying a 0.98ct vs a 1.01ct will save you money, whilst barely compromising on dimensions.
It’s also not linear, as in a 2ct diamond does not cost twice as much as a 1ct diamond. It will cost a lot more! This is because the larger the carat weight, the rarer, therefore more expensive.
There are generic dimensions for diamond carat weights based on ideal proportions, like 5mm will be approximately 0.5ct, but there are subtle variations, and these should only be used as a guide to estimate carat weight.
Diamond Carat weight to MM