Welcome Alchemist! Glad you're here.

I am an avid fan of JRR Tolkien's works in general, and I do not think that this premise is very similar at all to that of LotR, aside from the fact that several people want a very powerful object.

That is so loose an idea that it is not something to worry about. However, the jewel overall actually seems vaguely like a mashup of the one ring, the silmaril, and the palantir, which is quite odd.

I think it's a cool idea. It makes me curious. Why is Nickel tracing down the vial? Is he trying to destroy it? And what sort of 'alchemist' is his companion? With a story set on earth rather than an entirely different world it is best, in my belief, to be extra careful about what your cobha is, what it looks like, and how separate it is from real things like witch craft. What are the powers of the jewel?