This is facet rough of vivid, deep aqua-blue ytterbium aluminum garnet or YbAG, an exotic garnet very occasionally grown for use in lasers. The color is a very rich, vivid blue with a hint of green.
This is a very uncommon garnet, a cousin to the classic YAG but with all the yttrium replaced with ytterbium. Pure YAG is colorless, adding a bit of Yb gives the crystal pale green/aqua color. Going all the way to YbAG, replacing ALL the Yttrium with Ytterbium, results in a very vivid and deep aqua blue color as well as a slightly higher hardness and significantly higher density.
This material is an uncommon laser material and has never been available before as gem rough. This crystal was custom grown for us with a special formulation to enhance the color.
