The Edison Diamond Disc Phonograph and Diamond Disc Record are types of phonograph players and accompanying records marketed by Thomas A. Edison, Inc. from 1912-1929. The “Diamond” name comes from the phonograph’s diamond-shaped stylus. The records, proprietary in manufacture, could only be played on the Diamond Disc Phonograph, meaning they were incompatible with the lateral-groove record players (e.g. the Victor Victrola) that so many already owned. Edison, Inc. had previously only made phonograph cylinders, but expanded into disc production as shellac records grew in popularity. Thus, the Diamond Disc Phonograph and Diamond Disc Record collection were born.
A Diamond Disc Phonograph stands out for the diaphragm of the reproducer (what amplifies the sound) being parallel to the surface of the record.