Go from
this to this:
in a few simple steps.
I use GIMP, but it's translatable.
Crop and resize to 100x100
Duplicate base twice, set both layers to screen.
Create a new layer and fill it with #011634, set to screen.
Duplicate that layer, set to subtract.
Duplicate that layer, set to screen.
Create a new layer and fill it with #86AFEC, set to burn.
Create a new layer and fill it with #011634, set to subtract.
Then you're finished!
A piece of advice: The more screen layers you add the more orange your icon will become, so try not to use lots of screen layers, but if you need to I highly recommend putting some of them above the color layers.
When I was going over the xcf file I came across this:
. I thought it looked cool! To get this effect set the last layer to softlight.