Diamond moved to London to pursue a career as a musician and producer in 1969.
He signed on as a songwriter with Zomba after he moved to New York in 1980, and soon afterwards become known for his streamlined rhythm-and-blues pop style.
At Quincy Jones' request, Diamond also produced and co-wrote James Ingram's 1986 album Never Felt So Good.
Over the course of his career, Diamond produced and managed groups such as Starpoint and Fredrick Thomas, and also worked with several prominent performers including Donna Summer, Michael Bolton, Sheena Easton, Mick Jagger, Natural Selection and Don Johnson.
Diamond died in his Manhattan home on January 18, 1997, of a sudden heart attack.