Worldwide the standard unit used for weighing diamonds and gemstones is metric carat. It takes its name from the carob seeds, these seeds have a fairly uniform size and were used by early gem traders as counterweights in their balance scales. The modern metric carat was adopted by the internationally in 1913 and today a carat weighs exactly the same in every corner of the world.
Do not confuse Carat with Karat which refers to purity of gold.
One carat is equal to 200 milligrams or 1/5th of a gram. It can be further subdivided into 100 points or Cents, for example, a 50-points diamond weighs 0.50 carats.
- 1 Carat = 100 Cents
- 1 Carat = 0.200 Gram,
- 1 Gram = 5 Carat
- 1 Grain = 25 Cents
Ratti is another unit of measurement which was used in era before the rule of King Akbar and is still followed in India, specially to describe the weight of gemstones used for astrological and healing purposes. Ratti is actually a scarlet red seed of the plant Abrus precatorius, these seeds are fairly consistent in size and were used by Indians for weighing precious stones and even gold.
- 4 Chawal (grain of rice) = 1 Dhan (weight of one wheat berry)
- 4 Dhan = 1 Ratti
- 8 Ratti = 1 Masha
- 12 Masha = 1 Tola
Conversion of Ratti into Carats
- 1 Carat = 0.200 Gram
- 1 Ratti = 0.182 Gram
- 1 Ratti = 0.91 Carats
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