There is no restriction on importing paintings,sculptures and statutary,used stamps either as gifts or for commercial purpose.
You can import these items without any value limit by paying 14.712% as customs duty for commercial purpose and personal use.Of course bona fide gifts upto Rs 10,000/- is without any duty.
However,antiques are restircted as per Foreign Trade(Exemption from Application of Rules in certain cases) order 1993 and customs Notification 157/90 dated 28.03.90.
But antiquarian books are free to be imported and without any duty.Normally books of an age more than 100 years are considerd antique.