A glass candle is an object made out of dragonglass, also known as obsidian, made in the old Valyrian Freehold before its destruction four hundred years ago in the Doom of Valyria. Allegedly, using the power of magic they could be made to burn with light. With the return of dragons to the world in the possession of Daenerys Targaryen, their link with magic seems to be strengthening the ability of long-dormant magical powers and objects in the world. Glass candles which had not burned in centuries are now said to be burning with light.