first one with eevee
the next one with cycles with reduced Light Paths > Max Bounces (6) to speed up the render time. I am not used to Cycles, because my PC is a i3 and very slow while rendering with cycles, but I want to give it a try and experiment with subsurf scattering…
My next crown
I had some problems with the material of the gemstones and the topology could be better, but despise I am quite happy with the result and learned a few things while modeling.
Just my thoughts…
I would expect a thrown or sofa on which the crown lies.
And a table with cloth a bowl or vase with flowers (which are lovely).
Good Job!.
Thanks, FedPete for your inspiration and your thoughts. 
I like your ideas very much and I hope I will have time in the next weeks to visualize them.
Your crown looks great!
