The cordial was made from the juice of the Fire-Flowers grew in the Mountains of the Sun. It is obviously colored red due to the essence of the Fire-Flower. A drop would cure almost any illness or wound, even bringing people back from the brink of death. The bottle of the cordial was in was said to be made of diamond. She also received a little pouch and bandolier to carry the bottle around in with it. The bottle contained a limited amount of the cordial, so it had to be used sparingly - therefore, during the time the Pevensies ruled Narnia, Lucy was ordered by Peter not to carry it commonly to war, but to save it for great extremities.