Here's a tutorial about having armor in non-metallic metal in a few steps. At first NMM (non metallic metal) looks difficult, but I can assure you that with a little practice it goes fast and easy. NMM has the advantage to follow the highlights as you did put them on the miniature totally. Real metal has a tendency to pick up real light reflection, giving some times a strange result on the tabletop. Also, the NMM technique explained in this article, has a more illustrative overall sight about it.
Step 1 : The whole armor has to be painted in dark grey. Just leave the interstices in black base-coat. If you want to go real fast on this, a good dry-brushing technique will do it.
Step 2 : In the second step, it's really important to use your spotlight. Choose a side from where you want the light to reflect (preferably frontal/above). You can use the reflection of the spotlight to guide you and simply copy it with your paint (in this case levels of lighter grey). Per definition, it's right the same as any highlighting procedure.
Step 3 : Pick up the final lights with pure white. Again, you'll look at the reflection of the spotlight and put white spots of white where the light shines the most on the model. For chain mail, a dry brush from up to down will do.
Keep in mind this is more a fast painting technique, but it works very well. Hope you liked the tutorial and have fun. Cheers !