Protagonist wrote:
While back I heard optics and first surface mirrors are single point
diamond turned on special CNC lathes, than hand figured.
Last few months I've been working for an optics company, told my boss
about it, but he said it's imposable.
Single point diamond can't cut glass, not accurately.
I even showed him these web-sites here.

See: Large Optics Diamond Turning Machine
http://www-eng.llnl.gov/lodtm/

For instance, the Keck Telescope IR Secondary Mirrors were turned on
this machine. See: http://www-eng.llnl.gov/lodtm/pdf/HI_SPIE_DT1.pdf