This diamond could weigh about six carats if its measurement is 10mm x 10mm.
Carats indicates weight; mm indicates length and width -- the two are not necessarily compatible. However, if your diamond is a round brilliant cut diamond and its diameter at the girdle is 10mm, the diamond may be about four carats. If the cut is another shape, it may have a different carat weight.
If the diamond measures 7.5 x 7.5 mm, the diamond may weigh about two carats. You can ask a certified gemologist to weigh the diamond for an exact carat weight.
There are 45.52 carats on the hope diamond
Forty-five carats is large for any diamond. For reference, a five carat princess cut diamond measures 9.5 x 9.5 mm.
45.52 CaratsThe Hope Diamond is 45.52 carats. By comparison the average engagement ring is only 0.3 carats.
A round cut diamond weighing .25 carats measures 4.1mm at the girdle.
According to Wikipedia, below, this diamond weighs "755.5 carats (151 g)."
A round cut diamond weighing .25 carats measures 4.1mm at the girdle.
If the diamond is measured in points -- 106, you could translate this to 1.06 carats.
From Wikipedia: "The Cullinan diamond is the largest rough gem-quality diamond ever found, at 3,106.75 carats (621.35 g)."
You can read more about the Spirit of de Grisogono black diamond, below, which weighs 312.24 carats.
The diamond total weight is 3.0, so the total weight of all the diamonds is 3.0 carats.