As you are looking for the Diploma Courses for Commerce Graduates available in India , here I am providing the list of few of them.

PG Diploma in Preventive & Promotive Healthcare
Diploma in Paithani Handicraft & Modern Garments
Diploma in Banking & Services (DBFS) -2 Terms
Diploma in Education Technology (DET)
PG Diploma in Instructional Design (PGDID)
PG Diploma in Chemo- Informatics (PGDCI)
Diploma in Commodities Market (DICM)

List of few colleges which provides Diploma Courses for Commerce Graduates is given below:
Bharati Vidyapeeth University
Dhanraj Baid Jain College (Autonomous)
Dnyansagar Arts, Science and Commerce College
Indian Institute of Commerce and Trade (IICT)
Institute for Technology and Management
Institute for Technology and Management
Kousali Institute of Management Studies (KIMS)
R.N.I.S. College of Financial Planning
Sree Ramu College of Arts And Science
Yashwantrao Chavan Maharashtra Open University