same material - different output

Hello,
the material is the same for the whole object. Nevertheless there a dark spots on the rendered object.
Even when I remove the lamps, the dark spots are still there. And there is no object which casts shadows. So the dark spots are definitely no shadows of another object.
The material is a mixed shader: glossy and diffuse 50%, two different orange-yellow colours for the gold effect.
Can anyone help me? How can I fix this problem?
Thanks Lehrling

Attachments


Check face normals are all pointing outwards https://www.blender.org/manual/modeling/meshes/mesh_display.html?highlight=normals
Look at options to control smoothing https://www.blender.org/manual/modeling/meshes/editing/smoothing.html?highlight=shading
If the object is glossy check you the object is not reflecting a dark object

I see no blend file to review (why not ?)