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This coaster visual effect comes from each layer of the print being layed down in an opposing fashion.  This gives SILK PLAs a different reflection quality on subsequent layers.  A facet I took advantage of here.  Using .08 mm layer heights … that does mean there is < .5mm difference in height across the inner surface… totally not noticeable, IMO.

Recommend high or 100% infill.

0.16mm base layer

0.08mm layers for any circular surface layer visible.  

Use a high sheen PLA, like Silk PLA.  In my case, I am using Mika 3D silk PLAs.  I suspect not using a silk PLA will result in a much less visually appealing coaster.

I chose a 0.2 mm nozzle for the print as my surface layers are much finer quality, but that isn't necessary.

I chose to perform a color swap for the black outter edge, that is of course optional.