Fundamental Rights
(1) No title, not being a military or academic distinction, shall be conferred by the State. (2) No citizen of India shall accept any title from any foreign State. (3) No person who is not a citizen of India shall, while he holds any office of profit or trust under the State, accept without the consent of the President any title from any foreign State. (4) No person holding any office of profit or trust under the State shall, without the consent of the President, accept any present, emolument, or office of any kind from or under any foreign State.
India does not confer hereditary or aristocratic titles (like "Maharaja" or "Sir") - only military and academic honours are permitted. Indian citizens also cannot accept a title from a foreign country without government consent, and officials cannot accept gifts or positions from foreign states while holding public office, without the President's permission. This keeps public office free from foreign influence and preserves India's constitutional equality principle by not creating a titled aristocracy.
The National Awards (like the Bharat Ratna or Padma awards) are treated as civilian distinctions, not hereditary titles, and were held by the Supreme Court not to violate Article 18 - but if a citizen accepted a foreign knighthood without government clearance, that would raise an Article 18(2) issue.