This is the backside of a travertine tile. This is the side to which mortar will be applied. This is a good quality dense piece in that it has minimal holes, or air pockets showing. It will adhere better and have a smoother, more dense appearance on the top side.
In contrast, this travertine backside is full of holes, which means the top side will have lots of holes or fill, too. Travertine is priced by grade which is determined by weight. The more holes, the less it weighs, the lower the grade. So too, should the price.
A closer look at the same tile backside.
Even closer and you can see light shining through! Definitely a grade D tile.
It looks kinda cool, but this isn't a stone you want installed on your floor.
