If you look 'into' it, can you work out the reflections?
It's not as good as I wanted, but lets me think about the next try. Next, I want to get interesting mathsy shapes and colour patterns in there.
I did something similar a couple of months ago. This time I'm going for a less abstract, and more realistic view. This one cheats a little, by increasing the amount of light that internally reflects, so that you get more reflections.
Lastly, once you see the face, you can't 'unsee' it :o)
It's a 4K × 4K render, 256 reflections deep. I expect two days for the result, at best. But I think it'll be worth it.
I feel slightly consoled that I tweaked the processor to give a 25% boost, using only ~2% more power per computation, by under-volting to save energy, and fine-tuning elsewhere. As a result, I'm running 4 threads at 4.2GHz, at 65W and 60°C, on slow air cooling. This contrasts with the typical hot-headed overclocking approach of over-volting, using 100% more power and noisy cooling, for a 35% boost.
Despite this, it's a small consolation: bigger gains could be found by optimising the adaptive parameters of computation.