Nice carbonado ring there - i lean towards Diamonds in the Rough - I can't see the actual shape of the diamond though (from this photo) which would be interesting but modified forms from the octahedron, dodecahedron and cube can have both rounded faces, points and ribs and are referred to as: ìwhole diamondsî. If the diamond is elongated its known as an ìirregularî. These shapes are common to river bed and alluvial deposits and they reflect the rounding of edges that occur through weathering and transport from their surface origin to the place where they're found as a placer deposit. Neil
