Lateral diamond field emitters were fabricated by a diamond patterning technique that utilizes oxide patterning and lift-off process on a silicon-on-insulator wafer. An anode–cathode spacing of 2 μm between the diamond anode and cathode was achieved. The fabricated lateral diamond emitter diode exhibits excellent emission characteristics with a low turn-on voltage of ∼5 V and a high emission current of 6 μA, from four diamond fingers, at an anode voltage of 25 V. The emission current is stable over time, even at high emission current. The low turn-on voltage (turn-on field ∼3 V/μm) and high emission characteristics are among the best of reported lateral field emitter structures. The lateral diamond field emitter has potential applications in vacuum microelectronics, sensors, and microelectromechanical systems.