Burying the deceased for later renewal is the earliest known human ritual. The knowledge of early Christian art come to us from funerary contexts, sculptures and paintings of catacombs. The funerary and cemetery products are prefered in stone as stone is lastin, can be engraved and carved to desired shapes.
All sorts of stones can be used for the purpose. The stone funerary products are generally custom made for the seeker. Whatever inscrptions and statues etc. have to be installed are as per personal requirements.