Carat-Weight

It is the most obvious factor.
The unity of measure for diamonds is the carat, which corresponds to 0.20 grammes.
Below a carat, we talk about hundredths.

One carat is divided into 100 points so that a 0,25-diamond weighs 25 hundredths (or 25 points). The word "carat" comes from the carob seed, which was used a long time ago, in order to weigh gems.

The weight of a stone determines its size and its diameter.

Here are some examples of the size of diamonds with different weights: