The stones actually need to be a bit rounded, having come with glaciers in ice age, and polished/sanded by ice and wind/sand.
I prefer rendering the whole in TG, as I did quite some editing to the tgo. But it's not too bad now. TG can easily load it, it's just my old fashioned pre-occupation with lowest poly stuff. Fringes by mask work like a dream with the adjusted map.
So, here's a final for now. I can't post without some blurring though.