A novel device using single-crystal chemical vapour deposited diamond and resistive electrodes in the bulk forming a 3D diamond detector is presented. The electrodes of the device were fabricated with laser assisted phase change of diamond into a combination of diamond-like carbon, amorphous carbon and graphite. The connections to the electrodes of the device were made using a photo-lithographic process. The electrical and particle detection properties of the device were investigated. A prototype detector system consisting of the 3D device connected to a multi-channel readout was successfully tested with 120 GeV protons proving the feasibility of the 3D diamond detector concept for particle tracking applications for the first time. (C) 2015 Elsevier B.V. All rights reserved