These are lab-created LYSO (Lutetium-Yttrium Oxy-Orthosilicate) facet rough. Each is labelled with its gram weight and letter in the photo and they can be purchased individually.
This is LYSO, a really cool crystal with a clear base and rich blue fluorescence. It is grown for its incredible fluorescence, which makes it useful for detecting invisible radiation. It is insanely bright under a UV light and has a subtle blueish glow in sunlight which effectively changes its color to blue-violet. It has a hardness of 5.8 on average but it seems to be directional, what look like two directions of cleavage and an RI around 1.8.
