Start with your base, and sharpen it, whatever you like to do to your bases.
Duplicate the base and set to 100% overlay, and desaturate this layer.
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Flood fill #853E54 and set this layer to 100% lighten.
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Flood fill #002941 and set to 100% exclusion.
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Take this and set it to screen, put it at an opacity you like, I put mine to 40%.
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Set this one to lighten, I put it to 70%, you can choose what looks good for your icon.
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Stick this (or a color strip of your choice) and set to lighten, 70%.
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And that is that!!