reflection of an invisible object


I’m new to blender and I’d like to have some object to be only visible through “mirror” - I want to “enhance” reflections to make some object look more real in very simple scene, where there is not much to reflect so this object does not look reflective enough…

any suggestions?

(for those familiar with PovRAY - i want something similar to using “no_image” in object)

I played around with renderlayers to achieve this. I am not a composite nodes expert so there may be a better way - I would enjoy hearing other people’s comments on this question. Here is a blend file.