Hey,
Yes , you can do diploma in fashion designing after 12th .
There are several colleges which hold one or two-year diploma courses in fashion designing. They offer an internship based on the performance of the student. In diploma courses, you can learn different skills with a limited period of time, after completing your studies, you can be appointed to a well-known firm for the future career. There are so many doors open to reach at the acme of success.

Courses that are available

1) diploma in fashion designing - 1 year
2) PGD in fashion designing-1 year
3) Diploma in fashion designing and garment technology -1 year
4) UG diploma in fashion designing-1 year
5) certificate fashion designing
6) Diploma in fashion designing and merchandising

These courses are offered by many colleges where you can apply

Hey, 

You can do graduation in fashion designing which is for 3 years of degree courses affiliated to a well known institute.

There are several courses which hold one or year diploma coaching in fashion designing and they also offer internship.  

The minimum eligibility  criteria is 10+2 for bachelor degree courses with 50% marks and the admission procedure is strictly through a written entrance exam followed by a group discussion and an interview. 

Hope this helped. 

Thank you and keep asking .