Fig. 1 The weight of one carat of a diamond in grams
When choosing a piece of jewelry in a jewelry store, the first thing you look at is the tag. And when a piece of jewelry has diamonds, the tag always indicates their weight, but not in grams, but in carats. Of course, you have questions – how much does 1 carat of diamond weigh or how many carats are in 1 gram of diamond? Let’s answer it now.
Grams and carats: weight ratio
The ratio of grams to carats is 1:5. One carat of a diamond contains only 0.2 grams or 200 milligrams. Accordingly, there are 5 carats in 1 gram. The weight of gemstones is estimated only to thousandths of a gram (the third digit after the decimal point).
How the carat emerged
The history of weighing gemstones in carats begins in ancient Rome. Not having accurate scales at hand, Roman jewelers and merchants used other ways to determine the mass of stones.
There is a carob tree whose seeds are always the same size (about 1 cm) and weight – 0.2 grams, or, more precisely, 0.189 grams. This is the Ceratonia Siliqua tree. The seeds of Ceratonia siliqua served the Romans as a measure for determining the weight of a gemstone. The metric carat (full 0.2 grams) was officially approved relatively recently – in 1907 in France, and in 1922 – in the USSR.
As for the name of the weight measure, there are many versions. The most plausible one claims that the word came from Hebrew, having been transformed from “koret” (“pinch” – the distance between the thumb and index finger with a Ceratonia seed clamped in them) into “karat”. In favor of this version is the fact that originally in ancient Rome jewelers measured the weight of precious stones in “granules” (0.057 g) and “seliqua” – 0.189 g. The word “seliqua” comes from the name of the already mentioned carob tree Ceratonia Siliqua.