I just saw this posting before I left Dublin for Clonmel this morning, nice coincidence! I have passed the sign for the stone many times without seeing it, it points to a side road to your right coming from Cashel towards Clonmel but the help ends there. I drove up and down the road and saw nothing, after the second time I just thought 'sod it' and went back up once more since the crossroads on the other end has a sign for Cashel too. I just managed to catch a glimpse of it in a field to the right, the first gate after the sharp Z bend.
The gate into the field is now locked and wrapped with barbed wire, what was once a stile was blocked up with thorny branches. Nice. From the road side its easy to see the stone and the truly awful brick surround, maybe they have a grey rhino in the field and need to protect the public but in either case this stone has had its style severely cramped, a foresty plantation looks like its just about to swallow it up now too! A real pity, this would have been a wonderful stone with stunning views.
These pics are a couple of years old now. I happen to have passed the sign for this a few weeks ago and remembered I had called up here before.
Its a standing stone with two crosses on it, one incised into it the other standing out from the face. With a name like Giantsgrave you would think it was a megalithic tomb but this stone doesnt look like it could have been used in a tomb.
The standing stone is well sign-posted on the Clonmel to Cashel road.