Ok. Still working on this.

I used the sky dome as above, only at 100% for the render. But it was angled as above. I applied a blue sky with a few clouds texture.

I also applied a shiney chrome texture to the circlet and diamond_base, and did a reflection and refraction to the diamonds.

Here is the material room set up for the diamonds:

"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