On the origin of the carat as the unit of weight for gemstones

  title={On the origin of the carat as the unit of weight for gemstones},
  author={Tao Zhengzhang},
  journal={Chinese Journal of Geochemistry},
  • Tao Zhengzhang
  • Published 1 July 1991
  • Geology
  • Chinese Journal of Geochemistry
The carat is the unit of weight for diamonds and other gemstones. It corresponds to the average weight of the seeds of a leguminous tree. What kind of tree is this? We have studied the samples from Ethiopia. Egypt, Cyprus and the United States. The tree is neither “Kuara” nor “Locust” (Robina pseudoacacia Linn.), but rather Carob (Ceratonia Siliqua). In Ethiopia, as called by local inhabitants, “Kuara” is a species of Erythrina—E. brucei rather thanE. abyssinica.As might be expected, using the… Expand
Year : 2006 Seed size variability : from carob to carats
The seeds of various plants were used as weights because their mass reputedly varies so little. Carob (Ceratonia siliqua), which has given its name to the carat, is particularly famous in thisExpand
Seed size variability: from carob to carats
The variability of seeds sampled from a collection of carob trees was close to the average of 63 species reviewed from the literature, suggesting that human rather than natural selection gave rise to the carob myth. Expand