Reference:No Reflection Object Modifier

Syntax:

OBJECT {
  [OBJECT_ITEMS...]
  no_reflection
  }

This keyword is very similar in usage and function to the no_shadow keyword, and control an object's visibility.
You can use any combination of no_reflection, no_image and no_shadow with your object.

When no_reflection is used, the object will not show up in reflections. It will be seen by the camera (and through transparent/refractive objects) and cast shadows, unless no_image and/or no_shadow is used.