set gradient by oxoniensis to Color, 20% opacity >>
set gradient by _peccavi to Soft Light, 50% opacity >>
By now, your layers pallet should look like this:
Merge layers and go to Filter > Sharpen > Unsharpen Mask and set to the following settings:
Select the burn tool, and set to the following:
Run the brush over your whole icon and it should darken it a bit.
You should end up with this >>
I added text to get this >> I used Eurostile size 18 & Arial size 2.
Note 1: Don't use the final product as your own - this is so you can use the effect on other images. Note 2: Some changes might seem subtle (ex: adding a gradient might not change it too much), but it does change it a bit. This is just what I did to get the final product. Note 3: Every image is different. If the image you're using is lighter, you probably won't need to duplicate it thrice & set them all to screen. Your call.