He earned degrees in vocal performance from the Hartt School of Music, The Juilliard School, and the Naples Conservatory. He made his debut at the New York City Opera in 1961, as Nanki-Poo in The Mikado. His concert debut took place at New York's Town Hall, also in 1961. Diard's career began as a youngster. His great-aunt, the French prima donna, Fatmah Diard, a protegee of Jules Massenet, acquainted him with serious music and the French language. At the age of eight he sang with the Paulist Choir in New York, later becoming tenor soloist with "Chanticleer," touring Europe and the Far East. He recorded for RCA Victor. In 1966, he appeared in the world premiere of Carlisle Floyd's Markheim at the New Orleans Opera (opposite Norman Treigle and Audrey Schuh), later retiring to Hadlyme, CT, where the Diards made appearances and taught in their private studio. The following year he joined the voice faculty at the Hartt School where he taught until his retirement in 1988.
