Thanks! The chunk of glass was a tricky one: I could not polish it in the tumbler because the glass was too heavy and soft and the plastic pellets I normally use as cushioning could still scratch the surface at the final polish stage. Eventually I prepared a 2 micron Aluminum oxide paste on a cloth and finished it by hand over the course of a few hours...tedious work, but, not bad to pass the time if you are just watching D grade horror movies on Netflix.![]()