"Before the birth of carat to be used as a standard measurement, people used a carob, or carob seed or grain, or wheat grain to use as a system of measurement.The term ""carat"" goes back to the traders of the ancient world. A standard weight was required for precious gems as merchants of the ancient Mediterranean and Middle East were dependent on the ability to trade with a reasonably consistent
. unit of measurement. It was this need that lead to the adoption of seeds and grains as widespread accepted units of measurement. The carob seed and the wheat grain, both of which had been used for food purposes, were found to be ideal units of weight. This was a result of the fact that any given carob seed weighs, for all practical purposes, the same as any other given carob seed. In addition, any given grain of wheat has an identical weight to any other grain of wheat. In time, the carob seed became the standard unit of weight for gems. The word carob itself comes from the Arabic word for the carob seed, the quirat and eventually it was called a carat. For centuries the carob seed remained the weight measurement for precious gems. The carat, as it had become known, became linked to 4 grains Troy weight, with the carob seed having been abandoned at some point during the shift of trade centers. The Troy carat was the equivalent of approximately 205 milligrams. This measurement of weight lasted for the carat until the 20th century. In 1914 metric carat measurement of 200 milligrams was adopted."
