From what I found online, you have to have been overseas for more than 6 months to get the duty free allowances.
Jewelry for males 20 grams not costing more than Rs50,000
Jewelry for females 50 grams costing not more than Rs100,000
You will need receipts. Any jewelry over the allowance is taxed at 10.3%
Maximum limit is 1kg but you pay the tax on the amount you are over the above limits.
Any taxes must be paid in foreign currency.