These are some colleges offering diplomas either after 10th or 12th in India:

National Education Management & Technology Studies - Mumbai, Maharashtra
Gujarat Technological University - Ahmedabad, Gujarat
Nirma University - Ahmedabad, Gujarat
National Institute of Industrial Engineering - Mumbai, Maharashtra
National Institute Of Management - Mumbai, Maharashtra
Nirma Institute of Diploma Studies - Ahmedabad, Gujarat
Vasantdada Sugar Institute - Pune, Maharashtra
Lukhdhirji Engineering College - Morbi, Gujarat
GM College Of Diploma In Education, Kurnool, Andhra Pradesh
Shri Anand Diploma In General Nursing & Midwifery School, Rajkot, Gujarat
R.G.Bharvad Shri Jay Vadinath Diploma Pharmacy College, Palanpur, Gujarat
ITS in Engineering and Management, Aurangabad (Diploma in Engineering)
Orion Institute Of Management And Technology, Vadodara (Diploma in Engineering)
Priya Education Society Saraswati Institute Pune (Diploma in Engineering)
Shatabdi Institute Of Technology, Nashik (Diploma in Engineering)
A.V. Parekh Technical Institute, Rajkot (Part Time Diploma in Engineering)
A.W.H. Polytechnic College, Kuttikattoor (Diploma in Engineering)
Dinkarrao K. Shinde Smarak Trust Dr. A.D. Shinde Institute of Technology, Kolhapur
Government Polytechnic College, Neyyattinkara (Diploma in Engineering)
Government Polytechnic College, Meppadi (Diploma in Engineering
Bhadrak Institutes of Engineering and Technology - Balasore
Bharati Vidyapeeth's Jawaharlal Nehru Institutes of Technology - Pune
Dayanand Sagar College of Engineering Bangalore
Ghousia Polytechnic for Women- Bangalore
Government Polytechnic Amravati
Government Polytechnic College - Ahmedabad
Hindustan Academy - Bangalore
Institute of Rail Transport - New Delhi
Kalpana Chwala Government Polytechnic for Women - Ambala
Meera Bai Polytechnic for Women - Delhi
MEI Polytechnic Bangalore
Nirma Universitu of Science and Technology - Ahmedabad
Polytechnic for Women South Ext - Delhi
Rural Polytechnic for women - Ahmednagar
Govt. Polytechnic for Women, Haryana

The above mentioned institutes the below given some diploma courses:

Diploma in Fine Arts
Diploma in Mechanical Engineering
Diploma in Civil Engineering
Diploma in Electrical Engineering
Diploma in Computer Engineering
Diploma in Aeronautical Engineering
Diploma in Chemical Engineering
Diploma in Software Engineering
Diploma in Mining Engineering
Diploma in Petroleum Engineering
Diploma in Mechatronics
Diploma in Textile Technology
Diploma in Automobile Engineering
Diploma in Biomedical Engineering
Diploma in Elect. and Communication
Diploma in Electrical & Electronics Engineering
Diploma in Environmental Engineering
Diploma in Fashion Technology
Diploma in Fire Engineering
Diploma in Fire Safety Engineering
Diploma in Architecture Engineering
Diploma in Ceramic Technology
Diploma in Computer Science and Technology
Diploma in Computer Science and Engineering
Diploma in Rubber Technology
Diploma in Metallurgical Engineering
Diploma in Modern Office Practice
Diploma in Genetic Engineering
Diploma in Plastic Technology
Diploma in Dental Mechanics
Diploma in Business Administration
Diploma in Commercial Practice
Diploma in Hotel Mangement and Catering Technology
Diploma in Agriculture
Diploma in Cyber Security
Diploma in Cosmetology
Diploma in Beauty Culture
Diploma in 3D Animation