Locations of all three scrying stones in the Cold Run region, compiled by Neverwinter Wiki.http://neverwinter.gamepedia.com/Cold_Run_Scrying_Stones_Map
To reach the first one, you'll need to do a bit of climbing.
For the second stone, jump from the northern ledge. I was riding a 110% speed mount.
For the final one, drop down from the remorhaz area-
You'll likely need to do all three stones on the same character for it to count.