I would like to find out more about vortex energy. I have some good books on pedal power, windmills and kites. Major parts were ratted from my electric bicycle to fix the Adelaide University's Solar bicycle. I wonder if they got it all together in time for the start. Making Diamond tools Diamond tools are still made simply by rolling or casting diamond into copper.
Sand works well.
I have ground many valuable gems to dust with these primitive methods and am not alone in this opinion, as all the Lapidary people would agree.