His father, Vasile Diamandi-Aminceanu, advocated on behalf of the Aromanians and published the 1938 study Românii din Peninsula Balcanică.
He attended the literature and philosophy faculty of the University of Bucharest, where he was president of the Macedonian students' association and graduated magna cum laude in 1922.
Diamandi taught school in Turnu Severin, Roman, Iași, and Bucharest.
His first publication, the 1923 study Contribuția aromânilor în literatura neogreacă, was published in Peninsula Balcanică magazine.
His first book was Galeria oamenilor politici (1935), followed by Eroii revoluției ruse (1937), Galeria dictatorilor (1938), Oameni și aspecte din istoria aromânilor (1940), Fiul lui Dumnezeu – Fiul Omului (vol.