Exotic Units of Measurement
Most precision balances have a dozen or more units of measure. Typical applications include herbal medicine, gemstones & precious metals. We shall explore their origin, name and equivalent metric value.
CARAT Name from Italian carato, from Arabic قيراط, borrowed from Greek κεράτιον. Its value is based on carob seeds, which were claimed to have invariant mass. A unit for gemstones and precious metals found as early as the 15th century.
Value went from 187 mg in Cyrpus to 215.99 mg in Livorno. In 1877 the international carat was defined as 205 mg. In 1907 the 4th GCWM redefined it at 200 mg.
GRAIN Its value is based on a barley grain, which represents 1/7000 troy pound. Initially for pearls, diamonds and precious stones and now for bullets/arrows. Metrified in 1959 to 64.798 91 mg
PENNYWEIGHT Its value is equivalent to 24 grains, which is 1.555 173 84 g Lost its official UK status in 1878, but still used for precious metals. The symbol can be dwt or pwtl, in which the d comes from roman denarius.
MOMME The Japanese unit of mass equivalent to 1/1000 of Kan. The Kan was the base unit of mass in Japan. After 1891 value was set to represent 3.75 g.
BAHT A unit of mass from mainland Southeast Asia, with multiple probable origins. Attested as early as the 13th century and popularized as Tical by the Portuguese. A unit of measure from gemstones and precious metals.
The name varies per country, but the value is set to 15.244 g
Cambodia: baht Cambodia: tical Myanmar: kyat 16.33 g aprx Thailand: baht 15 g till 1902
TAEL Name Anglicization from Indonesia Malay tahil, meaning weight. Asian unit of mass equivalent to 1/16 Catty. Use can be found in medical herbs and silver exchange.
It did not reach value unification and different standards exist.
RO China: 37.5 g (Taiwan) PR China: 50 g (Since 1959)
Hong Kong: 37.799 364 17 g Singapore: 37.799 364 13 g
Thailand: 60.976 g
Vietnam: 37.5 g (gold) Vietnam: 100 g (food)
TOLA Indian and South Asian units of mass. Dates back to 1614 whose Sanskrit name तोला means weight. Traditionally equivalent to 100 Ratti seeds.
Now standardized to 180 troy grains or 11.663 803 8 g, the British-Indian base unit also served as the standard to measure Au & Ag. Just like the grain, both are no longer official, but still in use in many places.
MESHGAL A unit of Persia ≈ 4.6 g used for Saffron measurement. Its standardized value set to 4.608 294 93 g
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