An improved abrasive composite tool having a compositional gradient is disclosed and described. The composite tool can include a first region including abrasive particles, a second region, and a transition region connecting the first and second regions. The transition region can have a compositional gradient from the first region to the second region. The transition region can have compositional gradients among materials such as metals, ceramics, diamond-containing materials, polymers, or composites of such materials. The compositional gradient can include multiple intermediate regions or may transition directly from the first region to the second region. Most often, the transition region can be formed by vapor deposition methods such as PVD and CVD. Advantageously, the transition region can be formed on an abrasive tool to provide improved chemical and/or mechanical erosion resistance.