1paisa1967diamond shaped
2paise19628-fold symmetric
2paise19??8-fold symmetric, larger coin size
5paise1968smaller digit size
5paise1987larger digit, small emblem
5paise1975larger digit and emblem
5paise1976“food and work for all”
5paise1979“happy child, nation’s pride”
10paise1988small circular size. small c seen
10paise1988small circular size. small . seen (redundant?)
10paise1986small 8-fold symmetric
10paise1972large 12-fold symmetric
10paise19??“planned families” (1976?)
10paise1979“happy child”
10paise1980“Rural women’s advancement”
10paise1981“world food day”
10paise1978“food and shelter for all”
10paise1975“development, peace”
20paise1983Hexagonal shape. “fisheries”
20paise1988Hex. No star seen
20paise1983Small star at bottom (redundant?)
20paise1994slightly larger star seen (redundant?)
25paise1985“c” below year
25paise1987”.” below year (redundant?)
25paise195414 rupee
25paise1980“rural women’s advancement”
25paise1994Rhino. “.” below year
25paise1995Rhino. small diamond below year (redundant?)
25paise1995Rhino. nothing below year
50paise1993parliment house. small dot seen
50paise1995parliment house. small diamond seen (redundant?)
50paise1988parliment house. small c seen (redundant?)
50paise1985* below 98
50paise1990. below 99 (redundant?)
50paise1985* below 1 (redundant?)
50paise1982“national Integration”
50paise19??Indira Gandhi
1Re1997. below year
1Re1997o,M below year (redundant?)
1Re1985. below year, to the left (redundant?)
1Re1991diamond below year (redundant?)
1Re1986no mark below year (redundant?)
1Re1985H below year, to the left
1Re1988* below year (redundant?)
1Re1990Dr. Ambedkar
1Re1995“8th Tamil conference”
1Re1990“SAARC year”
1Re1989“world food day”
1Re1985“int. youth year”
1Re1992“golden jub. quit india movement”
1Re1994“year of family”
1Re1989“Nehru centenary”
1Re19??Mahatma Gandhi
1Re1990“15 years of ICDS”
1Re19??Rajiv Gandhi
1Re1980larger coin without .
1Re1975larger coin with . (redundant?)
2Rs1992“National Integration” with small diamond shape
2Rs1997as above with small star shape (redundant?)
2Rs1982“National Integration” larger coin size
2Rs1994“world food day”
2Rs1993“Bio diversity”
2Rs1995“8th Tamil conference”
2Rs19??“Sardar Vallabhbhai Patel” (1975?)
2Rs1995“Agri expo”
5Rs1994“world of work”
5Rs19??Indira gandhi, large coin

Some mint marks on Indian coins: (figure taken from a page by Paul Baker).

Some more about mint marks on Indian coins also from Paul Baker. RBI link for contemporary Indian coins