The sheet catalyst for synthesizing diamond features the low carbon steel or pure iron base and Ni and/or Co layer covering the base. The production process is electroplating to attach Ni and/or Co layer onto the surface of the base and includes the steps of continuous electroplating Ni and/or Co onto low carbon steel or pure iron band, heat diffusion annealing, laser heat shock treatment, cold finish rolling to harden, cutting into longitudinal strips, punching, surface treatment, sorting and packing. The catalyst, when used in synthesizing diamond, has the features of wide synthesizing range and high stability and can produce deep yellow diamond with good crystal form, high transparency and homogeneous granularity, being superior to available NiMnCo catalyst. |