Born in Manchester, England, after World War II, and his family moved to the United States when he was a young child. He was raised in New York City, on the Upper West Side, and graduated from the High School of Music and Art. He attended CCNY in NY, and the Art Students League of New York.

A fine arts major, Diamond turned to professional writing in his late twenties is best known for books such as The Haven, Lady of the Haven, The Thief of Kalimar, Black Midnight, Forest Wars, Marrakesh, Samarkand, and Samarkand Dawn. He soon turned to other genres; including historical fiction, thrillers, and later a true story of a Holocaust survivor's family during World War II, Maybe You Will Survive. Several of his books were published in the UK by Methuen.

Under the pen name Rochelle Leslie (the names of his two daughters), he authored Tears of Passion, Tears of Shame, a novel of South Africa set during the Zulu War of 1879 (Berkeley/Jove) which was subsequently published in Italy, titled, Venuto De Lontano, (To Come From Far Away) by Mondadori. He also has had various short stories published in anthologies.