Artificial diamond neutron detectors recently proved to be interesting devices to measure the neutron production on large experimental fusion machines. Diamond detectors are very promising detectors to be used in fusion environment due to their radiation hardness, low sensitivity to gamma rays, fast response and high energy resolution. High quality "electronic grade" diamond films are produced through microwave Chemical Vapour Deposition (CVD) technique. Two CVD diamond detectors have been installed and operated at Joint European Torus (JET), Culham Science Centre, UK. One of these detectors was a polycrystalline CVD diamond film, about 12 mm2 area and 30mm thickness while the second was a monocrystalline film of about 5mm2 area and 20mm thick. Both diamonds were covered with 2mm of Lithium Fluoride (LiF) 95% enriched in 6Li. The LiF layer works as a neutron-to-charged particle converter so these detectors can measure thermalized neutrons. Their output signals were compared to JET total neutron yield monitors (KN1 diagnostic) realized with a set of Uranium fission chambers. Despite their small active volumes the diamond detectors were able to measure total neutron yields with good reliability and stability during the recent JET experimental campaign of 2006.