This stone no longer exists (!), but used to be situated in a field between Belstane and Ainville, South of Kirknewton and South-west of Dalmahoy Hill. Click here for a location map provided by StreetMap.
In the Ordnance Survey map for 1853, a "boundary stone" was noted as existing at this location, which is thought to have been around five feet high. By the time of publication of the 1893 Ordnance Survey map, the stone was no longer recorded.
Belstane Stone, OS Map, 1853
It is possible that this stone has some relation to the nearby placename of Belstane, and, indeed, it is also possible that the stone itself was at one time known as such, lending the nearby locality its name. However, this remains pure conjecture, albeit a tempting one.