Boulder opal ring in sterling silver is a simple beauty in stunning symmetry. This opal shows a unique pattern in the host rock, with delicate fibers of shimmering green flashing throughout the stone like hidden streams. Boulder opals are cut from the opal's host rock which is most often ironstone. The opal deposits usually show up like rivers of color and shimmer within the stone. These are a very organic and natural-looking type of opal, resembling landscapes like this one, each one hand-painted by nature.