Age of Despair
A huge, square cut gem in the shape of a cube, 6" on a side. It is difficult to ascertain the base color of the gem or even the clarity of the stone because of the coruscating pulses of light and color from within its center. The most common color appears to be a violet light, but that is often mixed with portions of blue, red or even orange. The stone is never dark and would need to be heavily wrapped up to cover the light.
Detect Magic reveals an intense confluence of transmutation, evocation and abjuration arcane magic.