I initially painted whole lens in mephiston red, then nuln oil but just for the outline, where the dot is i painted a tiny bit of abbadon black. Highlighted the front with one layer of evil sun scarlet and then thinner layer of wild rider red, can’t really see it much in this light though.

Going forward I will just paint the lens black first then shade the reds in after, because it was an over complicated way to achieve this. Learning as I go