I just found my first treasure map, and it lead me to find a Moonstone. Only thing is i don't know what its use is?

Its description is following:

UNTRADABLE
Moonstone
Stone 1/99(Total:1)
A type of mineral, that when polished, emits an eerie blue glow not unlike the moon while under the influence of Thaliak.
Sells for 1,200 gil

I Hope that somebody can resemble the riddle about my mysterious shiney! xD