[JorisMX]

In order not to hijack an entire thread, here's my own mirror-mysteria

In this shot the mirror has a phong shading tag of 80° assigned to it with a highly reflective material using very high nd (150).
I tried renderings with lower phong and nd values without luck.

[Mattia Sullini]

Maybe you beveled edges? In any case, try to uncheck the smooth option for the mirror object and see what happens...

[JorisMX]

Hi Mattia,

yes indeed I beveled the edges to get a proper mirror edge.
I tried lowering the smoothing without any sucess.
I will try w/o smoothing next. thanks.

[wimver]

Joris,

the quickest way to solve this is adding a 1x1 plane in front of the existing mirror, or even just replacing the mirror by a plane. if the edges are important to you, keep the glass and add a mirror plane in front. offset the mirror plane by 0.1 mm from the glass.

wim