Chemical Vapour Deposition (CVD) diamond is being considered as a material for particle detectors in a harsh radiation environment. This article presents beam test results of 3D pixel detectors fabricated with poly-crystalline CVD diamonds. The cells of the devices had a size of 50 µm50 µm with columns 2.6 µm in diameter. The cells were ganged in a 32 and 51 pattern to match the layouts of the pixel read-out electronics currently used in the CMS and ATLAS experiments at the Large Hadron Collider, respectively. In beam tests, using tracks reconstructed with a high precision tracking telescope, a tracking efficiency of 99.3 % was achieved. The efficiency of both devices plateaus at a bias voltage of 30 V. Also irradiated poly-crystalline CVD diamond pad detectors were investigated. In high rate beam tests with particle fluxes up to 20 MHz/cm2 and irradiations up to 8 1015 n/cm2 it was shown that the pulse height of irradiated poly-crystalline CVD diamonds does not depend on flux to the .