Bismuth Germanate BGO12 Faceted Stones, Rare Scintillator Crystal Lab Evlitine

These are faceted, lab BGO12 (Bismuth Germanate), a rare scintillator crystal with incredible sparkle and fire.

This is a real cool rarity in the gem world: bismuth germanate (in this case, specifically Bi3Ge4O12 aka evlitine).  BGO12 was one of the first scintillator crystals, recognized for its inherent fluoresence to high energy radiation and useful for detecting X-rays and gamma rays.  Unfortunately its fluorescence is rather weak and requires high energies to activate--we can barely activate it with our most powerful 222nm UV light and the visible glow is rather weak.

BGO12 was the standard in devices like PET scanners until a revolution in scintillator materials began when LSO (lithium oxyorthosilicate) was discovered.  It has since been largely replaced by more and more powerful materials but still has a small niche of its own.

It also has incredible optical properties, with a high RI of 2.15 and dispersion of 0.1, which make it an amazing gem when faceted. Cut stones are exceptionally beautiful with high brilliance and play of color like liquid rainbows flowing within them.  Its only real downside is its hardness of 5 and brittleness which make it a firm collector's stone.  Note it also has a high density of 7.1!