Yes! as Jesse said, a sort of 'put instance on normal surface', instance (gem or any solide) with a 'distance box/cylinder' (with +- tolerance?) for distance with other instance and other solide/surface except the choosed 'put on surface' and a 'placement point' relative on 'put on surface'.

Recently have the prob: follow a path with 52 stone = array curve always fail (see pict); certainly (because Im a noob with MoI and) because curve was wrong... (?)
so have a tool to 'paint instance on surface' can be great.