Paint thinned down Kantor Blue to the coils and the edges around them.
Using Teclis Blue carefully paint the edges of the coils higher up to build a gradient. Paint around the edge of the coils with a thinner line too.
Using Hoeth Blue repeat the above step, taking it a little higher again.
Using Fenrisian Grey repeat the above step, taking it a little higher again. This time when painting the coils focus more on the edges either side of the gun and less in the middle.
Using White Scar create very small highlights along the very edge corner of the coils.
Finished product with the rest of the highlights and details.