Amarbir Singh is a numismatist with a strong interest in the history of India under European Influences as well as that of the Princely State of Hyderabad (Hyderabad State). He is an advanced researcher on the banknotes and coins of Hyderabad State. He also researches aspects of the coinage and paper currency of British India, French India, Indian Princely States, Indian currency used in Burma and India currency used in the Middle East. He is on the IBNS (International Bank Note Society) panel of experts. Amarbir founded the India Banknote Collectors' Chapter under the IBNS.
Amarbir has contributed to the leading numismatic publications on the subject. In the book, The Revised Standard Reference Guide to Indian Paper Money by Kishore Jhunjhunwalla, co-authored with Rezwan Razack, he has contributed the chapter on Hyderabad Banknotes (also known as the Osmania Currency banknotes). He has also contributed to the 'Standard Reference Guide to South Asian Coins and Paper Money since 1556 AD, Indian Edition', by Krause Publications. He was given a Certificate of Honor by Krause Publications in recognition of this contribution.
In National Numismatic Exhibition 2020, Amarbir was honoured with the 'Maestro of Indian Numismatics' award.
His some other notable contributions to various publications are as follows.
- In the book 'Hyderabad - Images and Memories' published by the English Daily Deccan Chronicle, which has 75 articles on the history of the Nizams of Hyderabad celebrating 75 years of Deccan Chronicle (founded 1938), 4 articles are written by him.
- In the series, Cultural Contours of History and Archaeology (ISBN 9789350500514), which is the collection of articles divided into ten volumes of thematic Specialization (Archaeology, History, Epigraphy, Numismatics, Art, Architecture, Buddhism and other Religions, Culture, Heritage and Literature, Vijayanagara Period, Tourism), Amarbir has contributed to Volume IV (Numismatics) with a chapter detailing the Rupee One Banknotes of the Nizam of Hyderabad.
- Rezwan Razack's second book 'One Rupee - One Hundred Years 1917-2017'
- Chapter on 'Banknotes of the Nizam' in the Emerald Jubilee souvenir publication of the Hyderabad Philatelic & Hobbies Society
- Bazil Shaikh's 'The Conjuror’s Trick: An Interpretative History of Paper Money in India'