The Solstone Stone Series Pietra Grey Quartz is a nonporous and durable alternative to stone countertops. Stone countertops have pores that can cause the surface to be less sanitary and stain more easily as they can hold particles that were meant to be wiped away. These particles can result in fungal or bacterial growth as well. This is why stone surfaces should be sealed every 1-3 months and Quartz countertops have become so popular. The Solstone Stone Series line is designed for those who want the look of stone, but the durability of quartz. Our Quartz is made of 93% natural quartz along with a high quality binding agent. This high content percentage of natural quartz results in an extremely scratch and stain resistant surface. Solstone Quartz carry's a limited lifetime warranty for as long as the original purchaser owns the home the sink was originally installed in.