Abstract: This invention relates to the manufacturing of a special "lump abrasive grains", which is to be used as polishing agent and in buffing compound. Basically, the production is composed of gypsum (CASO.sub.4.1/2H.sub.2 O), acting as a base carrier, and a certain kind of abrasive grains (e.g. emery, garnet or alumina), which is adopted in proper quantity and in regular size according to the polishing effect or purpose desired. Then by mixing with binder (e.g. water glass, methyl cellulose, glue, PVA, PVAC) and solidifying with water, new abrasive grains are aggregated in lump. As with its special nature, this new product will thereafter be easily processed into any extent of hardness, any particle size and shape as required.The main characteristics of this invention is illustrated as: during the instant of grinding, the lump grains are split into small lumps; and then ground into evenly fine grains so as to be able to extend the contact time and enforce grinding.