Drawing Armor, or rather armor reflection

Some of you may know that I sometimes do Saint Seiya art, and one thing that impresses me is the armor in the series. Every piece of SS drawing, from Kurumada's to Tetsurogi's LOST CANVAS, has a good touch in armor reflection.

Despite looking into the ideas of light and shadow, understanding the basics, I don't think I understand how this is placed on armor effectively (except maybe grooves?). How to make it look shiny, especially the Gold Saints.

Can someone help? Especially from those who do armor and/or Saint Seiya work.

I think I noticed that the contrast move horizontally (black, brown, light yellow, yellow, etc). Maybe I should ignore it...