Jane's reflector suggestion has serious merit. It can be a bit iffy in high ambient light conditions, but the whole idea of directing the light is well worth pursuing.

I've had limited success with trying the opposite to Jane's suggestion, by trying to cover over all but one side of a carving. It made me look ridiculous, trying to take a photo of a rock with me coat over me head, but hey, so it goes. I've even contemplated dragging a scanner and a laptop and trying scanography.

It's a problem that will be solved eventually.

I know what you mean about ropey photos. Hmm, rope. It's a throwaway thought, but would thin rope/thick string be useful to outline a motif? Probably not, it'd be a right pain having to cut it to the right length for each rock. But, it could be day-glo, which would stand out nicely. Shurrup Hob.