Natural stone, already millions of years old when quarried and manipulated for our own needs, would appear to be impervious to decay. It is important to treat natural stone surfaces with care using appropriate treatment methods. In the literature, there are many different methods of stone surface treatment in order to improve the aesthetic appearance of the surface of the marble slab or tile or to increase the roughness. A new concept, water jet treatment, currently used by the sector and have more popularity than traditional methods. Water jet technology enables to obtain a surface with required roughnesswhile preserving aesthetic appearance of the stone; however, this technology overcomes some disadvantages such as low productivity and high processing costs. Water jet treatment has been investigated in terms of surface quality, and the effects of working conditions on surface quality. The aim of this study is to determine the optimum working conditions of water jet surface treatment by using statistical and geostatistical methods. Laboratory and geostatistical studies have been carried out on Sardinia basalt samples under the conditions of different work distance, pump pressure and rate of progression.