My original recirculating heater was kind of a bluish green with a tiny bit of metallic. I tried to get it matched, but didn't get that close. The majority of them appeared to be a bronze hammered finish. Lots of guys use Rustoleum Hammered bronze paint. I got a can of that and may go with that when I get to that point in restoring the heater. I believe that Rustoleum used to have a light bronze, but it appears only dark hammered bronze is available now.
Link Here's a picture of one of the defrost nozzles on my bluish-green heater.
[on edit]The Hammerite paint that Deve used (WE b OLD's link) was a good match to the original, but unfortunately the whole line of Hammerite paint has been discontinued. If you could find a dusty can at an old hardware store that might be the ticket, but good luck on that.