Fantasy weapon WIP and question

Here is my current mesh for the Fantasy weapon challenge, i have been working on a war-axe.

You can view the mesh in 3d here if you like:

https://p3d.in/Lvwvd/wireonsmooth+spin

my question is this.
since the contest says they should be game weapons, is it ok to use refraction mapping?

I think it would really make the crystal on my axe pop nicely.

I am also planning to use bump and diffuse, but i already know they work fine in game engines