custom duty on Gold ornaments

I have heard that new custom rule warrants carriers of gold more than worh 20000 has to pay duty, Dow much is the duty? and is it exempted if purchased before the new law is imposed? Any one having similar experience at the Kolkata airport recently?
We need to raise our voice in different forums so that only those who smuggle gold to India are stopped. The allowable limit should be logical say 100 grms, not 8 grams. What is your view?