[DustyPorViva]

The outline is nice, but here is some pointers:

The only reason you would actually use dithering is to either give a 'rough' texture, or if your dealing with a low amount of high contrasting colors.

You have around 10 blue shades? didn't count, yet it barely shows any difference, which I find a waste of colors if your attempting dithering.

EDIT: BTW, a good thing for to do with metals is use one high contrasting bright color(white). Dithering kind of gives it a dull feeling, unless that is what you want of course.

But otherwise, it is a solid picture, good luck on dithering.