A substrate for depositing diamond by CVD, comprising a base body of hard material and a coating layer that holds diamond particles as seed crystal in a matrix and is deposited joined thereto on a surface of said base body, wherein: the seed diamond particles have an average particle size of 1 μm or smaller; the matrix comprises a first metal selected from a first group of Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W and/or a first compound between said first metal and a non-metallic substance selected from boron, carbon and nitrogen, said matrix holding the diamond particles distributed therein; and a joint zone developed as a result of a diffusion process and extending over said base body and coating layer comprises either or both atoms of said first metal and a component metal of the hard material.