I think we have a little mix up here. The refraction of gold is reflectiveness, which can obviously be below 1 because there is always something to reflect.
The values of water and air and glass are actually values with which the light is let through, in stead of bounced back. When letting light trough, if the value was wrong, the light would bend so much it was reflected in stead of passing through, resulting in no light passing trough, or blackness.
Just my logic though, no proof of this at all