Major banks in India sells pure 24-carat gold coins and bars over the counter in it’s branches. You can just walk into any bank who sells gold and purchase it from the bank teller. The bank provides 24-carat gold coins and bars.
Keep in Mind, Banks does not buy back coins gold sold by them, it is the biggest drawback. But you can sell the gold to any jewellery shop, without any need for purity check.