How can I tell if my slate tiles have been sealed?

Question

Just bought a home with new slate floors and slate bathtub walls. How can I tell if they have been sealed? If they have not, do they have to be sealed? And if they have to be sealed, where can I buy sealer at?
Also- there are marble or granite tile counter tops in the kitchen and bathroom. Do they have to be sealed?
Obviously I've never dealt with natural stone tiles before.
Thank you for your help!

Answer 1

check with your Realtor, look closely at the tiles, do they have a shine or any open seams,? put a drop of water on an area, if it rolls up it,s sealed