What I would like to see is:
1) hewn stone (or dressed stone, or ashlar). Can be made of regular stone times n (where n is amount of stone needed to create one hewn stone). Requires axe.
2) stone wall. I'd suggest it to be the same as brick wall. In order to make it similarly hard to make as brick wall, hewn stone can require quite a lot of stamina to make, and the stone wall requires a lot of hewn stone, let say 500 or even 1000 for first cornerpost.
3) replace/or add hewn stone to existing buildings
PS: want to remind about low tier rings: viewtopic.php?f=48&t=49989