Ambedkar jayanthi is celebrated on 14th April every year. Dr. Ambedkar was born on 14th April, 1891. It is a public holiday in all of the Indian states.
In addition to being a jurist, philanthropist, historian etc., he is also widely known for his active role as the Chairman of the Constitution Drafting Committee of India. You can find more information on Dr. Ambedkar here.
The below stamps depict Babasaheb Ambedkar and are issued by India.