I saw one of these on sale once but didn't buy them, and somehow never managed to find them again. (You can see them at http://www.dicecollector.com/D8_OPAQUE_ROUNDED_SPECKLED_KOPLOW_DOUBLING.jpg). So I might as well make one. Doubling octahedron, numbered 2-4-8-16-32-64-128-256; opposite faces *multiply* to 512.