does this sound like a copy?

ok so my friend and i were making up Rawak stuff, and i made up this rock and she says its a copy of a witch light from the Mortal Instruments, sejak Cassandra Clare. if anda don't know the series(City of Bones, City of Ashes, City of Glass, City of Fallen Bidadari and lebih coming out with the prequel Clockwork Angel, Clockwork Prince and lebih coming) a witch light is a stone that basically glows to give off light. i made this up and she berkata 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 sejak 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 anda 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 anda care
link
thanks anda guys! :)