Gloss is an important evaluation standard of the quality of stone veneers. The gloss, on one hand, depends on the refractive index of the various minerals of the stone, and on the other hand, is closely related to the micro-structure of the stone's surface.
The same kind of granite stones has similar mineral composition, so the smoother stone's surface, the higher gloss. The micro-structure of the stone's surface depends on the quality of grinding processes. So when purchasing granite stone, the identification of the grinding quality is essential. If we do not acquire some skills, the identification work will be very difficult.
There are pits and streaks on the stone surface left by grinding processes. Some of these pits and streaks are caused by its own mineral defects which can not be overcome in current processing conditions, some other, however, are caused by the mismatch of the thickness of grinding tools used in the processes.
To observe these very minor defects, we need to be very careful and learn a method. We can put an already processed granite stone veneer against the sunlight or the fluorescent light, and observe its reflective surface, and then a variety of pits and streaks can be found. The irregular small pits may be caused by the granite stone's own defects of its mineral composition, and can be ignored. However, if a number of regular streaks are found on the surface of the granite stone, this should be due to the poor processing quality. We should avoid this kind of granite stones when purchasing.
By:Hanjiang Wang
