PURPOSE: To improve the reliability of a product in manufacturing a composite jewelling material by surely metallurgically joining a molding body and base metal without a gap therebetween, forming a complete seam, cleaning the contour of the seam surface and clarifying the tone.

CONSTITUTION: Molding bodies 2, 2' having a predetermined design size are drawn out of two kinds of base metals 1, 1' different in colors and worked to be inserted into drawn-out holes 3, 3' in the base metals in different combination through wire cut electric discharge machining. The base metal and molding bodies are subjected to a pressure reducing process to extract gas from a gap between both joining surfaces and then subjected to a hot isotropic pressure process to surely give diffusion joining to the joining surfaces of the molding bodies and base metals. Thus, the contour of the joining surfaces of the molding bodies and base metals is clarified and the tone is cleared to prevent the joining surfaces from the formation of defective portions such as pinholes, blow holes, etc., so that a composite jewelling material having high reliability is provided.