Pre-cut presumably because they were smoothed by the water.
All right, that's a good enough approximation for DF, but I still object for 2 reasons:
1. If a small rock is shiny enough to be immediately used as a gemstone, it's shiny enough for a bird to steal it away to decorate its nest (which currently don't exist).
2. Dwarves are supposed to be renowned for their artistry, and craftwork par excellence. Are we now literally just picking trash up off the ground and saying, "Here, buy dis"?
are you calling coral garbage?
coral is considered a valuable gemstone