That looks like Cultured Stone to me. I forget who purchased the company, but you can find it by searching the net for "Cultured Stone." They have instructions on the site. I've used in inside and out.

We just frame some columns out to the size we needed them (take in consideration the thickness of the stone when planning the size), sheeted them with DuraRock, and then covered them with the stone, and grouted. Depending on the application you could probably get away with using drywall rather than DuraRock.

Thank you so much!