How do jewelers calculate the price of gold jewellery

There is a formula to decide the final price of gold jewellery. This is: Final Price of Jewelery = {Gold Price*(Weight in Grams)} + Making Charges + 3% GST + Hallmarking Charges. The price of gold also depends on its purity. Prices for 24KT, 22KT, 18KT or 14KT gold will vary.