don't forget that if a black hole has less than the current stable mass of a black hole (3 solar masses) then it evaporates, transforming its mass in radiation, in which case it would give off light, mostly X rays and gamma, at an increasing rate as its mass decreases, until the entire black hole is turned into a flash of hard radiation.

http://en.wikipedia.org/wiki/Hawking_radiation

However, this light is the mass of the black hole escaping in the form of the most basic form of energy.

Don't forget that if a black hole has less than the current stable mass of a black hole (3 solar masses) then it evaporates - transforming its mass in radiation, in which case it would give off light, mostly X rays and gamma, at an increasing rate as its mass decreases, until the entire black hole is turned into a flash of hard radiation.

http://en.wikipedia.org/wiki/Hawking_radiation

However, this light is the mass of the black hole escaping in the form of the most basic form of energy.