Conversion from Carat and Ratti to mg
1 Carat = 200 mg
1 Ratti = 121.5 mg (in ayurveda this Rati is used) or
1 Ratti = 182.25 mg
In India people generally buy and sell gemstones according to Rati weight, but it is advised to buy them according to Carat weight because carat is a standard measurement.
Ayurvedic Ratti
1 tola = 11.664 gms
1 tola = 12 masha
1 masha = 8 ratti
1 tola = 12 x 8 ratti
1 ratti = 121.5 mg
1 ratti = 0.6 carat (This is used for stone buying)
Gold Ratti
1 tola = 16 aane
1 aana = 4 ratti
1 ratti = 182.25 mgm
1 ratti = 0.9 carat
