The effective control over the behavior of nanostructured systems requires a tight control over the shape and size of the nanoparticle building blocks. This control can be very effective and useful in the case of crystalline gold nanoparticles. In order to achieve a precise morphology control over the particles obtained using gold nanorods as seeds; we have studied the crystalline structure of the initial single-crystal gold nanorods, which can be used in subsequent overgrowth processes. We also studied the mechanisms involved in the overgrowth and reshaping of such gold nanorods.