Section 2(1)(e) in The Customs Valuation (Determination of Price of Imported Goods) Rules, 1988.
(e)"similar goods" means imported goods -(i)which although not alike in all respects, have like characteristics and like component materials which enable them to perform the same functions and to be commercially interchangeable with the goods being valued having regard to the quality, reputation and the existence of trademark;(ii)produced in the country in which the goods being valued were produced; and(iii)produced by the same person who produced the goods being valued, or where no such goods are available, goods produced by a different person, but shall not include imported goods where engineering, development work, art work, design work, plan or sketch undertaken in India were completed directly or indirectly by the buyer on these imported goods free of charge or at a reduced cost for use in connection with the production and sale for export of these imported goods;