Upscale. According to Sina's financial information, Zhongnan Diamond is the most famous synthetic diamond industry in China. Zhongnan Diamond, located in Fangcheng County, Nanyang City, Henan Province, is the largest research and production base of superhard materials in the world. Zhongnan Diamond Company was awarded the honorary title of "five-star enterprise" and is the only "five-star enterprise" among the evaluated enterprises.