These are lab-created hyperfluorescent blue fluorite facet rough.
This is fluorite, a most unusual gem. Natural material is known for its incredible range of colors, as well as for some specimens that show very strong fluorescence (hence why the pheonomenon was named after the mineral). Specimens from the Blue John mine are known to change colors in sunlight because of their strong blue fluorescence, and this phenomenon attracted the interest of scientists. Crystals with a strong glow are valuable because they can be used as 'scintillators' for detecting the presence of invisible radiation, and it turned out if they grew fluorite with the element europium in it they could produce this very strong blue glow. Eu:Fluorite's glow is strong enough to change its color in direct sunlight.
Fluorite is not the easiest material to cut--its low hardness of 4, 4 directions of cleavage and very low refractive index require a careful approach. But the incredible blue glow makes it all worthwhile!
