I have leak on lower level coming through cement wall. Problem seems to be from above. Floor above is also stone and cement. How can I locate?

You first have to determine whether this is a pressure or a drainage leak.
To check to see if you have a hidden pressure leak first shut down everything in the house, no flush, no drinks of water, and if you are on a meter go out and check the little pointer in the gage. It should not move or creep. If it does you have a pressure leak. If you're on a pump then check the pressure gage after the pump builds up to pressure and shuts off. The gage should not fall and the pump come back on. If so then you have a leak. Let me know what you find. Hope this helps and thank you for rating my reply, Tom