Tom Dimond was born on a farm southwest of Britt, Iowa in 1904, and apparently named Leone Thomas Dimond, though he was later known as Thomas L. Dimond. His first four years of schooling were at a county school, known as the Dimond School, after which he moved with his parents into Britt in 1914. During the summer months, he helped out on the farm. He also played clarinet and saxophone with H.D. Green's dance band. He graduated from Britt High School in 1922. After graduating from the University of Iowa with a BE degree in electrical engineering in 1926, he was immediately offered a job with Bell Laboratories, then only a year old. He was shifted from job to job at Bell, which he liked, as it challenged him to learn new systems and stretch his creativity. During World War II, he worked with scanning apparatus and specialized in jamming equipment that blocked radio signals.

While working at Bell Labs he received over forty patents, including one for the "Dimond Ring" a complicated ring-shaped gadget made up of circuits that revolutionized the way telephones work. He also invented the "number reader," a device for transferring handwriting to computers. During his last ten years at Bell Labs he switched to executive positions. He retired from Bell Labs in 1967. He had married Ruth Clark in 1928, and while still living in New Jersey and using it as their home base, they travelled in the United States, Europe, South America, and Africa before moving to California in 1976, where they took up residence at Leisure World at Laguna Hills, a retirement community. Here he joined an inventors club.