Section 6(a) in The Merchant Shipping (Prevention of Collisions at Sea) Regulations, 1975
(a)Shapes shall be black and of the following sizes:(i)a ball shall have diameter of not less than 0.6 met;(ii)a cone shall have a base diameter of not less than 0.6 metre and a height equal to its diameter;(iii)a cylinder shall have a diameter of at least 0.6 metre and a height of twice its diameter;(iv)a diamond shape shall consist of two cones as defined in (iii) above having a common base.
