architectural salvage - stone finials

[markbigears]

I'm after a pair of aged ones for the gate pillars. Been looking about and they seem to be either:
,concrete,re-constituted stone or stone. I'm afer real stone ones. Is there a way of telling what's real stone?
Had a google but can't find anything definitive. Don't want to shell out a few hundred quid on aged new ones.
Many thanks fellas.