Ceratonia siliqua harubh. "Ceratonia siliqua", the scientific name of the carob tree, derives from the Greek "kerátiοn" κεράτιον 'fruit of the carob (from "keras" κέρας 'horn'), and Latin "siliqua" 'pod, carob'. The unit "carat", used for weighing precious metal and stones, also comes from κεράτιον, as alluding to an ancient practice of weighing gold and gemstones against the seeds of the carob tree by people in the Middle East. The system was eventually standardized, and one carat was fixed at 0.2 grams. In late Roman times, the pure gold coin known as the "solidus" weighed 24 carat seeds (about 4.5 grams). As
Gold coin example, a gold ingot identified as being .999 fine will be 999/1000 pure gold, with the other 1/1000 being impurities. Karat weight (K or kt) is a traditional fraction-based system used to denote the fineness of gold, with one karat being equal to 1/24 part of pure gold in an alloy. With the precision of modern assaying techniques, however, the fineness of gold ingots and bullion is more likely to appear as a decimal measurement. In this system, pure gold would be denoted as 1.000 fine. However, since absolutely pure gold is very soft and therefore not suitable for coinage