Stone contains natural crystals. These crystals reflect light to provide a shine on the surface. When the crystals are dull, crushed, or broken, they cannot reflect light evenly. For example, when the lens of a flashlight breaks, it cannot reflect the light that is being emitted from the bulb.
With the popularity of natural stone flooring, the general topic for discussion is that how to clean and maintain natural stones. And much debate arise when grout lines installed between natural stones are the most vulnerable and difficult place to clean. Admittedly, It allows for the expansion and contraction of the material during seasonal temperature fluctuations, preventing individual pieces from rubbing into one another and cracking. However the problem is that these spaces are susceptible to water penetration and the growth of bacteria.