Thank you, everyone.
Nice looking paint, Przemol. I wasn't sure what Mark was referring to with his comment. Glad he clarified. But who can say exactly what the colors should be?
Indeed, who can?

And these colours will be further modified with shading and later covered with satin varnish, so the colour intensity will change, too.
Looks great!
For small parts with brass or copper metal colours, I paint them silver or aluminium first, then use copper, brass or bronze -somehow these last 3 are more transparent then the first 2 and it gives a (to me) pleasing effect -even with the brush. 
Jeroen
Yes, brush painting is apparently problematic due to the semi-transparency. But I noticed no problems when airbrushing, especially using the Metal Color Vallejo paints. Model Color Vallejo Brass is a differnt story, though. I wish they would add this color to Metal Color series.