In order to make the existing highlights in this image stand out even more, first we make the lights and midtones of the image darker using a levels adjustment layer. After that we use our channels to select out our highlights and paint white over the selection on a new layer. Duplicating this layer adds even more highlights which can be made visible or invisible using a layer mask.
Lightening the Background
Since the background ended up darker than the original image, we paint white over the affected area and use layer blending modes to make it look just the way we want.