As a kind of top-grade building materials, decorative stone is known by few people about its classification and functions. Decorative stones can mainly be classified into natural stone and artificial stone. Normally, the stone in the market are marble, granite, terrazzo and synthetic stone. Among the marble stones, the white marble is of top-grade.Granite is harder than marble. Terrazzo is made from cement, stone granule. etc. Synthetic stone uses gravel of natural stone as its raw material, which is then pressed and polished with adhesive. The last two of the stones mentioned above are artificial stones. Thus they are harder than the natural stone.