Longstone, registered in Dezhou, Shandong Province and headquartered in Beijing, is a leading supplier of raw materials in China. Based on the importing and exporting business framework concerning products like metallurgy and minerals, and welding materials which have been operated by Sunstone International since its foundation in 1998, Longstone has keeping forging ahead with developing new products and exploring new markets in the fields of metallurgy, refractory, welding consumables, ...