Diamond Electric Specialties Corporation
Richmond St., Newark, New Jersey (1924)
102 South Orange Ave., Newark, New Jersey (1924)
43-45 South Wells Street, Chicago, Illinois (1921)

Diamond Electric Corporation
780 Freylinghousen Ave, Newark, New Jersey (1929)
Chicago, Illinois

Tube brand: Diamond

This company is mentioned in Tyne's "Saga of the Vacuum Tube", page 354. George Fathauer's book "Radio Tubes and Boxes of the 1920s" page 34 shows a box for the D171 A.C. tube (mentioning Newark and Chicago) and a company advertisement.

Diamond Electric Specialties started as a manufacturer of batteries, flashlights and lamps in 1912. The "Booth Report of Exibits at R.M.A. Show" (Radio, July 1929, p.38) mentions batteries and tubes for Diamond Electric Corp., which is a strong indicator that it's the same company, after presumably at some point dropping the "Specialties" from their name. Both firms had an office in Chicago.