PURPOSE: To provide an abrasive material having coarse outside surfaces and good polishing characteristics by treating the contents of a capsule under increased temperature and pressure for a time enough to create aggregated products of crushed materials.

CONSTITUTION: Diamond abrasive forming materials which include second phases including a high content of silicon in the form of silicon, silicon carbide or metal silicate are crushed into pieces which are introduced into a reaction capsule in a usual hightemperature and high-pressure device. Then, the reaction capsule is treated under preset high temperature and pressure for aggregating crushed pieces and collecting products from the reaction capsule. The collected products are abrasive materials which are aggregated and show hard quality and good characteristics and appearance at least similar to those of conventional diamond forming materials. The abrasive materials also have coarse outside surfaces, are fixed to the practical surface of a polishing tool and provides a good surface. The polishing tool specifically includes a drilling cutter, a cutting tool and a grinding wheel.