This is a very rare cabochon cut and polished locally . This is a green conglomerate puddingstone that was found in Michigan ! There is not many of these around . Personally I have only ever seen one other piece of rough available that is no longer available .  The pictures are shown in not much light ,average light and direct light . Measurements for this oval is about 31.83 x 21.21 x 5.70 mm at the deepest point..