The Render-> Lighting Effects filter is the secret solution. It allows you to select an Alpha channel for a 'height map'. White is high, black is low. I used the photograph straight, with some enhanced contrast, but you could choose to first re-brush it, to add extra height to the middle part and darken the parts you want low (burn/dodge). Of course I first clone-stamped the picture from the coin... Make a new alpha channel and past the adjusted photo in it, after selecting it. Below you see the settings I used.