does this sound like a copy?

ok so my friend and i were making up random stuff, and i made up this rock and she says its a copy of a witch light from the Mortal Instruments, door Cassandra Clare. if u don't know the series(City of Bones, City of Ashes, City of Glass, City of Fallen Angels and meer coming out with the prequel Clockwork Angel, Clockwork Prince and meer coming) a witch light is a stone that basically glows to give off light. i made this up and she zei its a copy and i would like your opinion.
Here is the thing i made up:
"A rock the size and shape of a golfball. Its dark blue and has a blue glow to it. It was created door witches in order to...." I call it the Larimar stone
and thats as far as i got it doesn't have a power yet, i still have to think of one so if u think of one while answering let me know. it has to be something important, that good and evil would want.(don't ask why we were doing this, we were stuck at a restaurant and decided to do this idk lol)
this is how i got the name of the stone if u care
link
thanks u guys! :)