PopCollector
Super Freak
The picture you posted showing the green tint shows the breakdown of the paint as it ages through the years.
The suit is indeed gun metal with purple airbrush highlights.
Sorry but according to the site that Brobocop posted this is what they state:
"The RoboCop suits are more green than anything when seen in real life - they're painted with a special photoreactive paint that registers metallic on film".