Thanks PixelDust, its a helmet with horns (the right horn its broken).

Maybe for me the more dificult for this helmet is found the space to apply the reflection without lost the shape, i have no much space, i will try on more time with your recomendations and will post in the WIP thread, thanks for your time 

In terms of how metal behaves, i would say that the bottom left one is the most correct in term on lighting
metal usually has sharp reflections so dithering should be avoided at all costs think of the lines you'd find on barcodes
you should also do the same on the right side using the darker color instead
when you are working on a sphere object you will get a lot more round sharp reflections instead of lines but for most other shapes like a cube, cylinder, pyramid etc you will get mostly these lines running across the length of the object

although I am not entirely sure on what the thing in the image is so the shape is a bit of the mystery
which makes it hard to make changes without breaking the intended design

you can fix this just by simply making the shading more defined, add lighting to it as if it is a sphere or a cube shape depending on what the shape is, then you should focus on adding the metallic rendering

here is a quick example 


also, you should post these type of stuff in the WIP thread you will get a lot more help there