Enamel. I forget the exact number but there aren't many to pick from. Just get a small pot from a modelling shop. The way I did it was to paint it liberally on and then use a piece of kitchen towel with a dab of white spirit to wipe off the surplus. Because the bits which used to be red are recessed you can wipe off surplus without removing the paint you want to leave behind. Worked a treat when the red lines washed off the tridents on my c-pillar.
check the instructions on the paint about surface preparation too - some of them are a bit fussy (according to my young nephew who paints a lot of world of warcraft type figures)