These are lab-created extra-bright LuAG (Lutetium Aluminum Garnet) facet rough. Each is labelled with its gram weight and letter in the photo and they can be purchased individually.
This is an ultra-bright variant of LuAG grown by one of the world's leading photonics companies. While conventional material is merely ridiculously bright this material upgrades it to 'bonkers' levels with an even brighter glow.
Cerium LuAG is what we call a 'lumogarnet' - a synthetic garnet with incredible fluorescence. It's my favorite lab gem! It is grown exclusively for lab and scientific applications as a 'scintillator', a hyperfluorescent crystal used in the detection of high-energy radiation like gamma rays. It has been used in industry for some time but never had a real introduction to the gem world until we finally tracked some down this year.
LuAG facets similarly to YAG (Yttrium Aluminum Garnet) - ie: pretty much perfectly and easily without much complaint. It has a hardness of 8.5 and no durability issues. It has very good optical properties with an RI of 1.83, just slightly better than yag. It fluoresces even more powerfully than Ce:YAG, with an intense yellow-green color. Even normal room lights will make it fluoresce, and outdoors with indirect sunlight can make it look like it is photoshopped into real life. It is just a great material overall. The faceted gems cut from this material are guaranteed to catch the eye!
My friend Eric Bardawil has cut the world's largest LuAGs which you can see on his instagram here https://www.instagram.com/reel/CbIVIz1ND_7/