Blind Eye Fluorite Faceted Gems

These are loose calibrated faceted stones of lab fluorite, cut with the opaque crystal edges at the culet in order to give a 'blind eye' effect.  These were grown for optics - fluorite has the lowest RI and dispersion of of any gem which means minimal chromatic aberration.  Since they're for use in optics, they do not have any fluorescence.

You might be wondering "why are fluorite gems is so rare when it's so cool?" That's because fluorite is a really tricky material to cut.  It has low Moh's hardness (rank 4 on the scale), and on top of that has four perfect cleavage planes - it wants to break into perfect octahedrons.  Therefore, it requires extreme care when cutting or setting - any mistake, and the gem can split in half.