Tear down the walls that imprison the mind... that is what the gems do. That is their true 'virtue'.
The moment my fingertips brushed the cool, silken planes of that first gem, I felt it. My skull ached, as if its contents were growing, pressing against the bone, searching for a way to break free.
That night, once the wine had dulled the pain enough to allow the onset of sleep, the dreams began. I have not been without them since. Nor would I be. Every spark of thaumaturgy that I wield, every device that I forge, every creature that I transfigure, I owe to these lessons cloaked in Nightmare.
From whence do these precepts hail? Certainly not the mundane grey between my ears. I possess only one reference that bears faith. Translated with unquestionable clarity by that idiot savant, Icius Perandus. "The Beast". Doryani of the Vaal knew the truth. Soon now, so shall I.