This is version 2 of this blend. Unfortunately I remarked animportant mistake of the first version only after uploading because I looked upon a gap between the main body and the edge (which was a torus) as shadow - I crave for your indulgence. Furthermore I think that the new edges without roundness look more true to style, the bangle is now more consistent and elegant.
One of the main challenges of this piece was to find and use the appropriate amount of topology. You only get a really perfect render with a file > 300 MB. As this is to much for a blendswap upload I was forced to decimate to 50%. I recommend you however the big version [https://www.dropbox.com/s/d6kmfz3voviohm4/Penrose%20Bangle.zip?dl=0].
It is very easy to change this blend according to your need: not only the material is replaceable but also the ornament because the displace modifier is not applied in these uploads.
Thanks for Gold go to elbrujodelatribu [www.blendswap.com/blends/view/38983] and [www.blendswap.com/blends/view/69793] and for theStudio Lighting Setup to RegusTtef [www.blendswap.com/blends/view/74897].
In addition to Blender I only used Gimp for the ornament. No compositing or postprocessing.