I think I'm doing something wrong. 

This is a free tiara from RDNA by Maveris according to the readme.  But I no longer see it on their site for download.

Anyway, here are screenshots of what I'm getting, which is nothing like a diamond....though at least it doesn't look like dull flat stuff this time, LOL

Here is the finished render.  I rendered it up close so it's esier to see.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi