Dear Mr Singh.
The facility of Gratuity is applicable to all 'Employees' as defined in section 2(e) of the Paymwnt of Gratuity Act 1972 which says:
2 (e) "employee" means any person (other than an apprentice) employed on wages, [3] [***] in any establishment, factory, mine, oilfield, plantation, port, railway company or shop, to do any skilled, semi-skilled, or unskilled, manual, supervisory, technical or clerical work, whether the terms of such employment are express or implied, [4] [and whether or not such person is employed in a managerial or administrative capacity, but does not include any such person who holds a post under the Central Government or a State Government and is governed by any other Act or by any rules providing for payment of gratuity].
Thus an "apprentice" employed under a contract of apprenticeship is excluded from the benifits under the Act and all other type of employees whether employed as temporary or probationary before confirmation are entitled to get gratuity from the date of their appointment, even if it is on temporary basis.
However you should be able to prove that you were appointed on temporary basis from 1-2-1985.
A judgement of Karnataka High Court, clarifuying the above point is attached herwith.