Kerateion
A kerateion (Greek: κερατεών) was a measure of weight and value used in ancient Greece and derived from the carob seed. The word itself is derived from the Greek word keras (κέρας), meaning "horn," which is thought to refer to the shape of the carob seed pod.
The kerateion was originally based on the average weight of a carob seed. The remarkable consistency in weight among carob seeds led to their adoption as a standard. Over time, the weight of the kerateion varied slightly from region to region and throughout different historical periods.
The kerateion was also used as a unit of value, particularly for precious metals such as gold. This usage is considered a predecessor to the modern carat, which is used to measure the weight and purity of gemstones, especially diamonds. While the modern carat (200 milligrams) is not identical to the ancient kerateion, it retains the historical connection to the weight of a carob seed.
The historical significance of the kerateion lies in its contribution to standardized measurement and trade in the ancient world.