These are vivid green lab created Vanadium YAG (Yttrium Aluminum Garnet) facet rough.
This is one of the best laser gems, vanadium YAG. It is used as a Q switch--adding a V:YAG crystal to some lasers turns them from a weak continuous-firing laser to a powerful pulsed laser that concentrates all of its energy into brief bursts of power. The color of this stuff is the most vivid green-green color I've seen in any gemstone. It's easily one of my favorite gemstones.
YAG is an amazing material for faceting - not only is it easy to cut, but it also has a high hardness (8.25-8.5), a solid RI (1.83), and good dispersion.
