Metal covered with glass makes the mesh always visible in cycles?

Question

I'm quite new to blender and totally thrilled about it. Recently, I tried to render a metal plate with concentric metal rings on it. The whole structure should be covered in glass, giving a flat surface in the end. I'm still not done with the materials and lighting, but the first rendered images look quite funny. To me it looks like I can always see how the structures was meshed, but I can't subdivide any further as I'm running out of RAM quickly. Also it feels like I'm seriouly doing something wrong here.

I'm using blender 2.81.16 with the builtin denoiser (switching it on/off doesn't change anything). I built 2 pieces (metal and glass) positioned very close to each other (maybe thats the problem??) and a sun as a light source.

Any Ideas what how to get a smooth render image? Here's a link to the blender file: https://file.io/p3S4Dc

Answer 1

Looks like overlapping geometry to me. What happens when you drag the glas object just a tiny bit upwards? – brockmann

Wow, that did the trick, thanks a lot! I also had to change the ring size so no face are touching anymore, now it looks perfect. Just out of interest - is there a less "hacky" way? Fusing both with a boolean operator didn't help.