Instruments other than bills and notes executed out of India.18. (1) Every instrument chargeable with duty executed only out of [India] and not being a bill of exchange or promissory note, may be stamped within three months after it has been first received in [India].(2) Where any such instrument cannot, with reference to the description of stamp prescribed therefor, be duly stamped by a private person, it may be taken within the said period of three months to the Collector, who shall stamp the same, in such manner as the [State Government] may by rule prescribe, with a stamp of such value as the person so taking such instrument may require and pay for.