First, the eye view, drop ink on the granite square ruler, if the ink quickly spread around the granite straight ruler, it means that the internal particles are loose, the quality of the stone is very poor. But if the ink droplets do not occur infiltration, internal particles in the granite ruler are dense, complex structure, stone quality is good.
The second kind is listening, hand striking the granite straight ruler, pay attention to the sound issued by the granite straight ruler, if the sound is clear that the granite straight ruler has good quality, the internal fine uniform and no cracks. If the sound is rough and boring, it proves that the granite rectangular angle is loose.