Light of Avanor
A woman of unknown origins known only as the Keeper of Lights, is the creator of the lamps.
The secrets of how they are made no one truly knows beyond the fact it involves magic of some form.
While they do not break as easy as household lamps they will burn out over a period of time depending on useage. City lamps can last for years, but the smaller portable ones usually only last for a week.
Despite how valuable they are, they cost a very reasonable amount by most standards.
While 100 silver coins may seem a high price to some, it is quite low considering the safety it grants from the perptual darkness.
In early years the lamps kept the creatures of the woods that evolved with the darkness at bay, but over time the denziens of the wilds have adapted further and now the light offers very little protection. It does however allow one to see, which most people find a rather useful thing.